JP2018095699A - Polypropylene composition, method for producing the same and polypropylene sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polypropylene composition excellent in sheet moldability and capable of obtaining a sheet excellent in transparency and rigidity.SOLUTION: Provided is a polypropylene composition being a polypropylene based polymer composed of a propylene single polymer of 30 to 70 mass% and a propylene-ethylene random copolymer of 30 to 70 mass%, in which an ethylene content is 0.5 mass% or lower, Mw/Mn is 6 to 20, a xylene insoluble matter amount is 97 to 99 mass%, the stereoregularity (mmmm) of the xylene insoluble matter is 97.5 to 99.5%, in a final melting curve, the ratio of the components having a melting peak temperature of 165°C or higher and having a melting temperature of 170°C or higher is 5% or higher, and also, the ratio of the components having a melting temperature of 160°C or lower is 15% or higher, further, a crystal nucleus agent of 0.18 to 0.5 pt.mass is included to 100 pts.mass of the polypropylene based polymer, and a melt flow rate is 1 to 10 g/10 min.SELECTED DRAWING: None

Description

  The present invention relates to a polypropylene composition, a method for producing the polypropylene composition, and a polypropylene sheet comprising the polypropylene composition.

  Polypropylene is inexpensive and excellent in rigidity, moisture resistance, and heat resistance, and is suitable as a sheet material used for food packaging, fiber packaging, and the like. For example, a container using polypropylene is used as a food container having heat resistance, but problems remain in terms of strength, and in order to make up for it, we give it a thickness or add many ribs, Problems such as increased costs and difficulty in viewing the contents arise. In addition, transparency is required for food containers so that the contents can be confirmed, but since polypropylene is a crystalline resin and becomes a translucent sheet as it is, the addition of a crystal nucleating agent as an improvement measure It has been known. However, it is still difficult to obtain sufficient transparency.

  In order to improve the transparency of the molded article of the polypropylene composition, for example, Patent Document 1 proposes a method of adding a crystal nucleating agent. Moreover, the method of extending | stretching as a method of improving the rigidity and transparency of a polypropylene is well-known (patent document 2).

International Publication No. 2013/125504 JP-T-2004-517199

  However, according to the knowledge of the present inventors, it is difficult to simultaneously achieve high transparency, high rigidity, and good sheet formability (uniform stretchability) by the methods of Patent Documents 1 and 2.

  An object of the present invention is to provide a polypropylene composition that is excellent in sheet formability and that provides a sheet having excellent transparency and rigidity, a method for producing the polypropylene composition, and a polypropylene sheet comprising the polypropylene composition. is there.

[1] 30 to 70% by mass of a propylene homopolymer and 30 to 70% by mass of a propylene / ethylene random copolymer, an ethylene content of 0.5% by mass or less, and a molecular weight distribution (Mw / Mn) of 6 to 20 Heating and cooling so that the xylene insoluble content at 25 ° C. is 97 to 99% by mass, the stereoregularity (mmmm) of xylene insoluble content is 97.5 to 99.5%, and the maximum heating temperature is sequentially decreased. The polypropylene-based polymer satisfying the following conditions (B-i) to (B-iii) having a melting curve by thermal analysis when reheating after repeating a plurality of times, and 100 parts by mass of the polypropylene-based polymer A polypropylene composition characterized by comprising 0.18 to 0.5 parts by mass of a crystal nucleating agent and having a melt flow rate of 1 to 10 g / 10 min.
(Bi) The melting peak temperature is 165 ° C. or higher.
(B-ii) The proportion of components having a melting temperature of 170 ° C. or higher is 10% or higher.
(B-iii) The proportion of components having a melting temperature of 160 ° C. or lower is 15% or more.
[2] A polypropylene sheet comprising the polypropylene composition of [1].
[3] A method for producing the polypropylene composition of [1], wherein the polypropylene polymer is obtained by a multistage polymerization method having two or more polymerization steps continuously, or one of monomer concentration and polymerization conditions. Or the manufacturing method of the polypropylene composition characterized by mixing using the polymerization apparatus which has both gradients, and mixing the obtained polypropylene polymer and the said crystal nucleating agent.
[4] In the polymerization step, (A) a solid catalyst containing as an essential component an electron donor compound selected from magnesium, titanium, halogen, and a succinate compound; (B) an organoaluminum compound; and (C) the outside [3] The method for producing a polypropylene composition according to [3], wherein a catalyst containing an electron donor compound is used.

  The polypropylene composition of the present invention is excellent in sheet moldability, and a sheet excellent in transparency and rigidity can be obtained.

It is a graph which shows an example of the temperature pattern at the time of obtaining a last melting curve. It is an example of a final melting curve.

<Measurement method>
The values of each physical property in the present invention are as follows.
[Molecular weight distribution (Mw / Mn)]
The molecular weight distribution (Mw / Mn) of the polymer or copolymer is a value obtained by measuring the mass average molecular weight (Mw) and the number average molecular weight (Mn) by gel permeation chromatography and calculating Mw / Mn. .
PL GPC220 manufactured by Polymer Laboratories is used as an apparatus, 1,2,4-trichlorobenzene containing an antioxidant is used as a mobile phase, and UT-G (1) and UT-807 (1) manufactured by Showa Denko KK are used as columns. ), UT-806M (two) connected in series was used, and a differential refractometer was used as a detector. Moreover, the same solvent as the mobile phase was used as the solvent of the sample solution, and the sample for measurement was prepared by dissolving at a sample concentration of 1 mg / mL for 2 hours while shaking at a temperature of 150 ° C. 500 μL of the sample solution thus obtained was injected into the column and measured at a flow rate of 1.0 mL / min, a temperature of 145 ° C., and a data acquisition interval of 1 second. For column calibration, a polystyrene standard sample (Shodex STANDARD, manufactured by Showa Denko KK) having a molecular weight of 580 to 7.45 million was used and approximated by a cubic equation. The Mark-Houkins coefficient is K = 1.21 × 10 ⁻⁴ , α = 0.707 for the polystyrene standard sample, K = polypropylene homopolymer, propylene random copolymer, and polypropylene-based polymer. 1.37 × 10 ⁻⁴ , α = 0.75 was used.

[Amount of xylene insoluble matter]
2.5 g of polymer was dissolved in 250 ml of xylene at 135 ° C. with stirring. After 20 minutes, the solution was cooled to 25 ° C. with stirring and then allowed to stand for 30 minutes. The precipitate was filtered through filter paper, the solution was evaporated in a stream of nitrogen, and the residue was dried at 80 ° C. under vacuum until a constant weight was reached. Thus, the mass% of the polymer soluble in xylene at 25 ° C. was calculated. The amount of xylene-insoluble matter (mass% of the polymer insoluble in xylene at 25 ° C.) is determined by (100−mass% of the soluble polymer) and is considered to be the amount of the isotactic component of the polymer.
The xylene-insoluble matter was collected by thoroughly washing off xylene remaining in the precipitate with methanol and then drying it at 80 ° C. under vacuum.
[Tacticity of xylene insoluble matter (stereoregularity) mmmm]
The mmmm insoluble matter xmm obtained by the above method is the JNM LA-400 (13C resonance frequency 100 MHz) manufactured by JEOL Ltd. for a sample dissolved in a mixed solvent of 1,2,4-trichlorobenzene / deuterated benzene. From the spectrum measured by the ¹³ C-NMR method used, the ratio of the intensity of the peak corresponding to the pentad in which four meso (m) bond sequences of the propylene monomer were continuously obtained was calculated according to A. It was determined according to the method described in Zambelli, Macromolecules, 6, 925 (1973).
[Melt flow rate (MFR)]
The melt flow rate of the polypropylene composition is a value measured under conditions of a temperature of 230 ° C. and a load of 21.18 N according to JIS K7210.

<Polypropylene composition>
The polypropylene composition of the present invention contains a polypropylene polymer and a crystal nucleating agent.
The polypropylene polymer comprises a propylene homopolymer and a propylene / ethylene random copolymer. 30-70 mass% is preferable with respect to a polypropylene-type polymer, 40-70 mass% is more preferable, and 50-70 mass% is further more preferable.

  Mw / Mn of the polypropylene polymer is 6 to 20, and has a relatively broad molecular weight distribution. When the Mw / Mn is not less than the lower limit of the above range, excellent rigidity can be easily obtained in a molded article made of a polypropylene composition, and when the upper limit is exceeded, production of a polypropylene polymer becomes difficult.

The amount of xylene insolubles in the polypropylene polymer is 97 to 99% by mass. The component insoluble in xylene of the polypropylene polymer corresponds to an isotactic component having crystallinity. In contrast, a component soluble in xylene contained in a small amount in a polypropylene polymer corresponds to an atactic component having no crystallinity and has a lower molecular weight than a component insoluble in xylene. Therefore, the melt characteristics of the polypropylene composition and the physical properties of the molded product are mainly influenced by components insoluble in xylene. The amount of xylene insolubles in the polypropylene polymer of 97 to 99% by mass indicates that the crystalline component of the polypropylene polymer is 97 to 99% by mass. When the crystalline component of the polypropylene polymer is less than 97% by mass, the rigidity of the molded article made of the polypropylene composition is particularly lowered.
The xylene insoluble matter (crystalline component) of the polypropylene polymer has a stereoregularity (mmmm) of 97.5 to 99.5%. If mmmm is less than 97.5%, the rigidity and heat resistance, particularly heat resistance, of the molded body made of the polypropylene composition is lowered.

  The ethylene content in the polypropylene polymer is 0.5% by mass or less, preferably less than 0.3% by mass. A minimum is more than 0 mass%, and 0.1 mass% or more is preferable. Transparency is improved by random copolymerization of ethylene with propylene. When the ethylene content in the polypropylene-based polymer is 0.5% by mass or less, excellent rigidity is easily obtained in a molded article made of the polypropylene composition.

The polypropylene-based polymer has a melting curve by thermal analysis when the heating and cooling are repeated a plurality of times so that the maximum heating temperature is successively lowered and then reheated (hereinafter, this melting curve is referred to as “final melting curve”). ) Satisfies the following conditions (Bi) to (B-iii).
(Bi) The melting peak temperature is 165 ° C. or higher. Preferably, the melting peak temperature is 167 ° C. or higher, more preferably 169 ° C. or higher. The melting peak temperature is substantially 186 ° C. or lower.
(B-ii) The proportion of components having a melting temperature of 170 ° C. or higher is 10% or higher. Preferably, the proportion of components having a melting temperature of 170 ° C. or higher is 15% or higher, more preferably 20% or higher.
(B-iii) The proportion of components having a melting temperature of 160 ° C. or lower is 15% or more. Preferably, the proportion of components having a melting temperature of 160 ° C. or lower is 18% or more, more preferably 20% or more.
When the melting peak temperature of the polypropylene polymer is less than 165 ° C., or the proportion of the component having the melting temperature of 170 ° C. or more is less than 10%, the rigidity of the molded body made of the polypropylene composition becomes insufficient. On the other hand, if the proportion of the component having a melting temperature of 160 ° C. or lower is less than 15%, the moldability becomes insufficient.

Here, the final melting curve will be described.
The final melting curve is obtained using a conventional differential thermal analyzer (DSC). Specifically, first, the measurement sample is once melted and then cooled. Next, as shown in FIG. 1, the heating and cooling are repeated a plurality of times so that the maximum heating temperature sequentially decreases, and then reheating is performed, and the thermal analysis of the measurement sample during the reheating is performed, and the final melting curve is obtained. obtain. The thermal analysis of the final melting curve is the same analysis as a normal DSC and is simple.
FIG. 2 shows an example of the final melting curve. The peak temperature (Tm _p ) in this final melting curve is taken as the melting peak temperature.
In the heat treatment in which heating and cooling are repeated several times so that the maximum heating temperature is lowered successively, annealing of the measurement sample and subsequent crystallization by cooling are repeated in order from the high temperature, so that the crystals can be easily made in order from molecules with few defects. Can be formed. In addition, a crystal composed of molecules with many defects formed at a low temperature during cooling melts while being held at the subsequent heating and maximum heating temperature until the maximum heating temperature is sufficiently lowered. Hereinafter, the heat treatment in which heating and cooling are repeated a plurality of times so that the maximum heating temperature is sequentially lowered is referred to as “repetitive annealing treatment”.
In heating / cooling in the repeated annealing treatment, for example, heating is performed to Ts ₁ at a constant rate of temperature increase, the temperature is maintained, and then cooled to 20 ° C. at a constant rate of temperature decrease, and then Ts ₁ -5 [° C.] (This temperature is set to Ts ₂ ) Heating is performed at a constant temperature increase rate, and the temperature is maintained, and then cooled to 20 ° C. at a constant temperature decrease rate. Then, heating and cooling are repeated so that the maximum heating temperature Tsn at the _n-th heating becomes Ts ₁ −5 × (n−1) [° C.]. When ts _n repeats until 80 ° C., reliable results even for major components is defective.
Further, in the reheating when obtaining the final melting curve, in order to obtain the melting behavior of all the crystals obtained by annealing at each maximum heating temperature and subsequent crystallization at the time of cooling, The temperature is raised from ℃ to 200 ℃ or higher. Crystals consisting of molecules with few defects crystallized at high temperature have a high melting point, whereas crystals consisting of molecules with many defects crystallized at low temperature have a low melting point, so the final melting curve reflects the distribution of defects in the sample.

The ratio of the component having a melting temperature of 170 ° C. or higher is the percentage of the melting enthalpy at 170 ° C. or higher with respect to the total melting enthalpy determined from the final melting curve. On the other hand, the ratio of the component having a melting temperature of 160 ° C. or lower is the percentage of the melting enthalpy at 160 ° C. or lower relative to the total melting enthalpy determined from the final melting curve.
In either case, it is calculated as the ratio of the partial area to the total area of the melting peak on the baseline.

  The MFR of the polypropylene composition of the present invention is 1 to 10 g / 10 minutes, and preferably 2 to 7 g / 10 minutes. When the MFR is not less than the lower limit of the above range, excellent moldability is easily obtained when the polypropylene composition is molded into a sheet. When the sheet is not more than the upper limit, excellent secondary formability is easily obtained when the sheet is thermoformed.

The polypropylene composition of the present invention contains a crystal nucleating agent. Addition of a crystal nucleating agent contributes to improvement of transparency. Specific examples of the crystal nucleating agent will be described later.
Content of a crystal nucleating agent is 0.18-0.5 mass part with respect to 100 mass parts of polypropylene polymers in a polypropylene composition, and 0.2-0.4 mass part is preferable. When the content of the crystal nucleating agent is 0.18 parts by mass or more, the transparency improving effect is excellent. Even if it exceeds 0.5 parts by mass, further improvement in transparency cannot be expected and the cost increases.

[Crystal nucleating agent]
The crystal nucleating agent is preferably selected from nonitol nucleating agent, sorbitol nucleating agent, phosphate ester nucleating agent, triaminobenzene derivative nucleating agent, carboxylate metal salt nucleating agent, and xylitol nucleating agent. In particular, for the purpose of improving transparency, it is more preferable to use a nonitol nucleating agent or a sorbitol nucleating agent.
As a crystal nucleating agent having a nonitol-type structure, for example, 1,2,3-trideoxy-4,6: 5,7-bis-[(4-propylphenyl) methylene] -nonitol, a crystal having a xylitol-type structure As a nucleating agent, for example, bis-1,3: 2,4- (5 ′, 6 ′, 7 ′, 8′-tetrahydro-2-naphthaldehydebenzylidene) 1-allylxylitol, bis-1,3: 2, 4- (3 ′, 4′-dimethylbenzylidene) 1-propylxylitol, a crystal nucleating agent having a sorbitol structure, for example, bis-1,3: 2,4- (4′-ethylbenzylidene) 1-allyl Sorbitol, bis-1,3: 2,4- (3′-methyl-4′-fluoro-benzylidene) 1-propylsorbitol, bis-1,3: 2,4- (3 ′, 4′-dimethylbenzylidene) 1'-methyl-2'-propenyl sorbitol, bis-1,3,2,4-dibenzylidene 2 ', 3'-dibromopropyl sorbitol, bis-1,3,2,4-dibenzylidene 2'-bromo- 3′-hydroxypropyl sorbitol, bis-1,3: 2,4- (3′-bromo-4′-ethylbenzylidene) -1-allyl sorbitol, mono 2,4- (3′-bromo-4′-ethyl) Benzylidene) -1-allylsorbitol, bis-1,3: 2,4- (4′-ethylbenzylidene) 1-allylsorbitol, bis-1,3: 2,4- (3 ′, 4′-dimethylbenzylidene) Examples thereof include 1-methylsorbitol, bis (p-methylbenzylidene) sorbitol, 1,3: 2,4-bis-o- (4-methylbenzylidene) -D-sorbitol and the like.
Nonitol-based commercially available crystal nucleating agents used in the composition of the present invention include, for example, Millad NX8000 (Milliken Japan), and sorbitol-based commercially available crystal nucleating agents such as RiKAFAST R-1 (New Japan Rika), Millad 3988 (Milliken). Japan), Gerol E-200 (New Japan Rika), Gelall MD (New Japan Rika), and the like. Examples of the phosphate ester crystal nucleating agent include aluminum-bis (4,4 ′, 6,6′-tetra-tert-butyl-2,2′-methylenediphenyl-phosphate) -hydroxide. Examples of commercially available phosphoric ester crystal nucleating agents used in the composition of the present invention include Ascus tab NA-21 (ADEKA) and Ascus tab NA-71 (ADEKA). Examples of the triaminobenzene derivative crystal nucleating agent include 1,3,5-tris (2,2-dimethylpropanamide) benzene. Examples of commercially available triaminobenzene derivative crystal nucleating agents used in the composition of the present invention include IRGACEAR XT386 (BASF Japan). Examples of the carboxylic acid metal salt nucleating agent include 1,2-cyclohexanedicarboxylic acid calcium salt. Examples of commercially available carboxylic acid metal salt nucleating agents used in the composition of the present invention include Hyperform HPN-20E (Milken Japan).
In particular, in order to maintain transparency after secondary processing (heating), it is preferable to use a nonitol nucleating agent, a sorbitol nucleating agent, or a phosphate ester nucleating agent.
These crystal nucleating agents can be used alone or in combination of two or more.

[Other additives]
The polypropylene composition of the present invention can contain other additives other than the crystal nucleating agent as long as the effects of the present invention are not impaired.
Examples of other additives include antioxidants, neutralizers, chlorine absorbers, heat stabilizers, light stabilizers, UV absorbers, internal lubricants, external lubricants, antiblocking agents, antistatic agents, and antifogging agents. And conventional additives commonly used for polyolefins such as flame retardants, dispersants, copper damage inhibitors, plasticizers, crosslinkers, peroxides, oil extended and other organic and inorganic pigments. The addition amount of each additive may be a known amount.

[Method for producing polypropylene composition]
The polypropylene composition of the present invention is obtained by producing a polypropylene polymer and mixing a crystal nucleating agent and other additives as required.
A propylene homopolymer is obtained by supplying a propylene monomer, a catalyst, and, if necessary, a molecular weight regulator to the reaction system and polymerizing the propylene monomer.
The propylene / ethylene random copolymer is obtained by supplying a propylene monomer, an ethylene monomer, a catalyst, and, if necessary, a molecular weight regulator to the reaction system, and copolymerizing the propylene monomer and the ethylene monomer.
As the polymerization method, a known method such as a slurry process (polymerization in a liquid monomer) or gas phase polymerization can be used.
A molecular weight regulator known in the art such as a chain transfer agent (for example, hydrogen or ZnEt ₂ ) may be used.
The polymerization temperature is preferably 40 to 100 ° C, more preferably 50 to 90 ° C, and further preferably 60 to 90 ° C. When the polymerization temperature is less than the lower limit of the above range, productivity and stereoregularity of the obtained polypropylene are lowered.
The polymerization pressure is preferably 25 to 45 bar (2.5 to 4.5 MPa), more preferably 27 to 45 bar (2.7 to 4.5 MPa) when the polymerization pressure is carried out in the liquid phase. When carried out in the gas phase, a range of 5 to 30 bar (0.5 to 3.0 MPa) is preferred, and 8 to 30 bar (0.8 to 3.0 MPa) is more preferred.

The polypropylene-based polymer is preferably obtained by a multistage polymerization method having two or more stages of polymerization, in which subsequent polymerization is performed in the presence of a product formed during the immediately preceding polymerization reaction. Alternatively, a prepolymerized propylene homopolymer and a propylene / ethylene random copolymer may be melt-kneaded.
A multi-stage polymerization method is preferred in that a polypropylene polymer satisfying the conditions (B-i) to (B-iii) can be easily obtained.
There are no particular limitations on the number and order of multistage polymerization, and generally 2 to 5 stages are used, and an appropriate order is selected in consideration of productivity and the like. In the multistage polymerization method, in particular, a polymer obtained in both stages by forming a polymer by performing the second stage polymerization with a catalyst dispersed in the polymer component formed in the first stage polymerization. Disperse in a state close to the molecular level.
The polymerization process in each stage in the multi-stage polymerization method may be performed by a slurry method performed in the presence of an inert hydrocarbon such as hexane, heptane, kerosene, or a liquefied α-olefin solvent such as propylene, or a gas phase in the absence of a solvent. You may carry out by the polymerization method and may combine these.
As the reactor in each stage of the polymerization process, for example, a stirred bed reactor, a fluidized bed reactor, a circulation reactor, or the like can be used, and it can be produced by any of continuous, semi-batch, and batch methods. .
In order to obtain a polypropylene polymer that satisfies the conditions (B-i) to (B-iii), a polymerization vessel having a gradient of monomer concentration and polymerization conditions may be used. In such a polymerization vessel, for example, a monomer in which at least two polymerization regions are connected can be used, and the monomer can be polymerized by gas phase polymerization. Specifically, in the presence of a catalyst, a monomer is supplied and polymerized in a polymerization region including a riser, and a monomer is supplied and polymerized in a downcomer connected to the riser. The polymer product is recovered while circulating. This method comprises means for completely or partially preventing the gas mixture present in the riser from entering the downcomer. Also, a gas and / or liquid mixture having a different composition from the gas mixture present in the riser is introduced into the downcomer. As the above polymerization method, for example, a method described in JP-T-2002-520426 can be applied.

When the polypropylene polymer of the present invention is produced by a multistage polymerization method, for example, after a propylene homopolymer is formed in the first stage, a polymerization catalyst is further added in the presence of the propylene homopolymer in the second stage. A method for producing a propylene / ethylene random copolymer can be used.
For example, it is preferable that the first step is performed by a slurry method and the second step is performed by a gas phase polymerization method because a copolymer having high solubility in propylene is easily generated. Moreover, it is preferable from the point of productivity when all the steps are performed by the slurry method.

In the production of a polypropylene polymer, it is preferable to carry out homopolymerization of propylene and copolymerization of propylene and ethylene using a catalyst component including the following components (A), (B), and (C).
(A) Component: A solid catalyst containing, as an essential component, an electron donor compound selected from magnesium, titanium, halogen, and a succinate compound as an electron donor compound.
Component (B): an organoaluminum compound.
Component (C): an external electron donor compound selected from silicon compounds.

[Component (A): Solid catalyst]
The component (A) can be prepared by a known method, for example, by bringing a magnesium compound, a titanium compound and an electron donor compound into contact with each other.
As the titanium compound used for the preparation of the component (A), a tetravalent titanium compound represented by the general formula: Ti (OR) _g X _4-g is preferable. In the formula, R is a hydrocarbon group, X is a halogen, and 0 ≦ g ≦ 4. As titanium compounds, TiCl ₄ and more specifically, TiBr _4, titanium tetrahalides such as _{TiI 4; Ti (OCH 3)} Cl 3, Ti (OC 2 H 5) Cl 3, Ti (O n -C 4 H _{9) Cl 3, Ti (OC} 2 H 5) Br 3, Ti (OisoC 4 H 9) trihalide, alkoxy titanium such as _{Br 3; Ti (OCH 3)} 2 Cl 2, Ti (OC 2 H 5) 2 Cl ₂ , Di (halogenated alkoxytitanium) such as Ti (O _n —C ₄ H ₉ ) ₂ Cl ₂ , Ti (OC ₂ H ₅ ) ₂ Br ₂ ; Ti (OCH ₃ ) ₃ Cl, Ti (OC ₂ H ₅ ) ₃ Cl _{, Ti (O n -C 4 H} 9) 3 Cl, Ti (OC 2 H 5) 3 monohalogenated trialkoxy titanium such as _{Br; Ti (OCH 3) 4} , Ti (OC 2 H 5) _{4, Ti (O n -C 4} H 9) 4 and the like tetraalkoxytitanium such. Among these, preferred are halogen-containing titanium compounds, particularly titanium tetrahalides, and more particularly preferred is titanium tetrachloride.

  (A) As a magnesium compound used for preparation of a component, magnesium compounds which have a magnesium-carbon bond or a magnesium-hydrogen bond, for example, dimethyl magnesium, diethyl magnesium, dipropyl magnesium, dibutyl magnesium, diamyl magnesium, dihexyl magnesium, di Examples include decylmagnesium, ethylmagnesium chloride, propylmagnesium chloride, butylmagnesium chloride, hexylmagnesium chloride, amylmagnesium chloride, butylethoxymagnesium, ethylbutylmagnesium, butylmagnesium hydride and the like. These magnesium compounds can also be used, for example, in the form of a complex compound with organic aluminum or the like, and may be liquid or solid. Further preferred magnesium compounds include magnesium halides such as magnesium chloride, magnesium bromide, magnesium iodide, magnesium fluoride; methoxy magnesium chloride, ethoxy magnesium chloride, isopropoxy magnesium chloride, butoxy magnesium chloride, octoxy magnesium chloride, and the like. Alkoxymagnesium halides; aryloxymagnesium halides such as phenoxymagnesium chloride and methylphenoxymagnesium chloride; alkoxymagnesiums such as ethoxymagnesium, isopropoxymagnesium, butoxymagnesium, n-octoxymagnesium and 2-ethylhexoxymagnesium; phenoxy Allyloxy Magnesium like Magnesium, Dimethylphenoxy Magnesium ; Magnesium laurate, such as carboxylic acid salts of magnesium such as magnesium stearate and the like.

  The electron donor compound used for the preparation of the component (A) is generally referred to as “internal electron donor”. In the present invention, it is preferable to use an internal electron donor that gives a broad molecular weight distribution. A composition polymerized using the catalyst is a composition having the same molecular weight distribution obtained by pellet or powder blending a polymer polymerized using another catalyst, or by a multistage polymerization method, or by monomer concentration or polymerization. It exhibits different properties from a composition having the same molecular weight distribution polymerized by a method using a polymerization vessel having a gradient of conditions. This is because the composition produced using the catalyst is integrated in a state where the high molecular weight component and the low molecular weight component are closer to the molecular level, but the latter resin composition is mixed in a state close to the molecular level. This is probably because the molecular weight distributions are not the same but only show the same molecular weight distribution. However, it is not realistic to express this in words in the claims. Hereinafter, preferred internal electron donors will be described.

(Internal electron donor)
A preferred internal electron donor in the present invention is a succinate compound. In the present invention, the succinate compound means a diester of succinic acid or a substituted succinic acid. Hereinafter, the succinate compound will be described in detail. The succinate compound preferably used in the present invention is represented by the following formula (I).

In which the radicals R ₁ and R ₂ are identical or different from one another and optionally contain heteroatoms, C ₁ -C ₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkyl An aryl group; the groups R _{3 to} R ₆ are the same or different from each other and are hydrogen, or optionally a heteroatom, C ₁ -C ₂₀ linear or branched alkyl, alkenyl, cycloalkyl, aryl, The groups R _{3 to} R ₆ which are arylalkyl or alkylaryl groups and are bonded to the same carbon atom or different carbon atoms may be bonded together to form a ring.

R ₁ and R ₂ are preferably C ₁ -C ₈ alkyl, cycloalkyl, aryl, arylalkyl, and alkylaryl groups. Particularly preferred are compounds wherein R ₁ and R ₂ are selected from primary alkyls, especially branched primary alkyls. Examples of suitable R ₁ and R ₂ groups are C ₁ -C ₈ alkyl groups such as methyl, ethyl, n-propyl, n-butyl, isobutyl, neopentyl, 2-ethylhexyl. Ethyl, isobutyl, and neopentyl are particularly preferred.

One preferred group of compounds represented by formula (I) are branched alkyl, cycloalkyl, aryl, arylalkyl, wherein R _{3 to} R ₅ are hydrogen and R ₆ has 3 to 10 carbon atoms. And an alkylaryl group. Preferred specific examples of such mono-substituted succinate compounds include diethyl-sec-butyl succinate, diethyl hexyl succinate, diethyl cyclopropyl succinate, diethyl norbornyl succinate, diethyl perihydrosuccinate, diethyl Trimethylsilyl succinate, diethyl methoxy succinate, diethyl-p-methoxyphenyl succinate, diethyl-p-chlorophenyl succinate, diethyl phenyl succinate, diethyl cyclohexyl succinate, diethyl benzyl succinate, diethyl cyclohexyl Methyl succinate, diethyl-t-butyl succinate, diethyl isobutyl succinate, diethyl isopropyl succinate, diethyl neopentyl succinate, diethyl isopenty Succinate, diethyl (1-trifluoromethylethyl) succinate, diethyl fluorenyl succinate, 1-ethoxycarbodiisobutylphenyl succinate, diisobutyl-sec-butyl succinate, diisobutyl hexyl succinate, diisobutylcyclopropyl succinate , Diisobutyl norbornyl succinate, diisobutyl perhydrosuccinate, diisobutyl trimethylsilyl succinate, diisobutyl methoxy succinate, diisobutyl-p-methoxyphenyl succinate, diisobutyl-p-chlorophenyl succinate, diisobutyl cyclohexyls Succinate, diisobutylbenzyl succinate, diisobutylcyclohexylmethyl succinate, diisobutyl-t-butyl succinate Diisobutyl isobutyl succinate, diisobutyl isopropyl succinate, diisobutyl neopentyl succinate, diisobutyl isopentyl succinate, diisobutyl (1-trifluoromethylethyl) succinate, diisobutyl fluorenyl succinate, dineopentyl-sec- Butyl succinate, dineopentyl texyl succinate, dineopentyl cyclopropyl succinate, dineopentyl norbornyl succinate, dineopentyl perhydrosuccinate, dineopentyl trimethylsilyl succinate, dineo Pentylmethoxy succinate, dineopentyl-p-methoxyphenyl succinate, dineopentyl-p-chlorophenyl succinate, dineopentylphenyl succinate, dinene Opentyl cyclohexyl succinate, dineopentyl benzyl succinate, dineopentyl cyclohexyl methyl succinate, dineopentyl-t-butyl succinate, dineopentyl isobutyl succinate, dineopentyl isopropyl succinate, di Neopentyl neopentyl succinate, dineopentyl isopentyl succinate, dineopentyl (1-trifluoromethylethyl) succinate, dineopentyl fluorenyl succinate.

Another preferred group of compounds within the scope of formula (I) are C ₁ -C ₂₀ linear, wherein at least two groups from R _{3 to} R ₆ are different from hydrogen and optionally contain heteroatoms. Or a branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl, or alkylaryl group. Particularly preferred are compounds in which two groups different from hydrogen are bonded to the same carbon atom. Specifically, R ₃ and R ₄ are different from hydrogen, and R ₅ and R ₆ are hydrogen atoms. Preferred specific examples of such disubstituted succinates are diethyl-2,2-dimethylsuccinate, diethyl-2-ethyl-2-methylsuccinate, diethyl-2-benzyl-2-isopropylsuccinate, diethyl 2-cyclohexylmethyl-2-isobutyl succinate, diethyl-2-cyclopentyl-2-n-butyl succinate, diethyl-2, 2-diisobutyl succinate, diethyl-2-cyclohexyl-2-ethyl succinate , Diethyl-2-isopropyl-2-methylsuccinate, diethyl-2-tetradecyl-2-ethylsuccinate, diethyl-2-isobutyl-2-ethylsuccinate, diethyl-2- (1-trifluoro Methylethyl) -2-methylsuccinate, diethyl-2-isopentyl-2- Sobutyl succinate, diethyl-2-phenyl-2-n-butyl succinate, diisobutyl-2,2-dimethyl succinate, diisobutyl-2-ethyl-2-methyl succinate, diisobutyl-2-benzyl- 2-isopropyl succinate, diisobutyl-2-cyclohexylmethyl-2-isobutyl succinate, diisobutyl-2-cyclopentyl-2-n-butyl succinate, diisobutyl-2,2-diisobutyl succinate, diisobutyl-2 -Cyclohexyl-2-ethyl succinate, diisobutyl-2-isopropyl-2-methyl succinate, diisobutyl-2-tetradecyl-2-ethyl succinate, diisobutyl-2-isobutyl-2-ethyl succinate, diisobutyl -2- (1-trifluoro Tilethyl) -2-methylsuccinate, diisobutyl-2-isopentyl-2-isobutylsuccinate, diisobutyl-2-phenyl-2-n-butylsuccinate, dineopentyl-2,2-dimethylsuccinate, dineopentyl 2-ethyl-2-methyl succinate, dineopentyl-2-benzyl-2-isopropyl succinate, dineopentyl-2-cyclohexylmethyl-2-isobutyl succinate, dineopentyl-2-cyclopentyl-2-n-butyl Succinate, dineopentyl-2,2-diisobutyl succinate, dineopentyl-2-cyclohexyl-2-ethyl succinate, dineopentyl-2-isopropyl-2-methyl succinate, dineopentyl-2-tetradecyl-2-ethyl succinate , Dineopentyl-2-isobutyl-2-ethyl succinate, dineopentyl-2- (1-trifluoromethylethyl) -2-methyl succinate, dineopentyl-2-isopentyl-2-isobutyl succinate, dineopentyl 2-Phenyl-2-n-butyl succinate.

Furthermore, compounds in which at least two groups different from hydrogen are bonded to different carbon atoms are particularly preferred. Specifically, it is a compound in which R ₃ and R ₅ are groups different from hydrogen. In this case, R ₄ and R ₆ may be a hydrogen atom or a group different from hydrogen, but it is preferable that either one is a hydrogen atom (trisubstituted succinate). Preferred examples of such compounds are diethyl-2,3-bis (trimethylsilyl) succinate, diethyl-2,2-sec-butyl-3-methylsuccinate, diethyl-2- (3,3,3- Trifluoropropyl) -3-methylsuccinate, diethyl-2,3-bis (2-ethylbutyl) succinate, diethyl-2,3-diethyl-2-isopropylsuccinate, diethyl-2,3-diisopropyl-2 -Methyl succinate, diethyl-2,3-dicyclohexyl-2-methyldiethyl-2,3-dibenzyl succinate, diethyl-2,3-diisopropyl succinate, diethyl-2,3-bis (cyclohexylmethyl) ) Succinate, diethyl-2,3-di-t-butylsuccinate, diethyl-2,3-diisobuty Succinate, diethyl-2,3-dineopentyl succinate, diethyl-2,3-diisopentyl succinate, diethyl-2,3- (1-trifluoromethylethyl) succinate, diethyl-2,3- Tetradecyl succinate, diethyl-2,3-fluorenyl succinate, diethyl-2-isopropyl-3-isobutyl succinate, diethyl-2-tert-butyl-3-isopropyl succinate, diethyl-2- Isopropyl-3-cyclohexyl succinate, diethyl-2-isopentyl-3-cyclohexyl succinate, diethyl-2-tetradecyl-3-cyclohexylmethyl succinate, diethyl-2-cyclohexyl-3-cyclopentyl succinate, diisobutyl -2,3-diethyl-2-iso Lopyl succinate, diisobutyl-2,3-diisopropyl-2-methyl succinate, diisobutyl-2,3-dicyclohexyl-2-methyl succinate, diisobutyl-2,3-dibenzyl succinate, diisobutyl-2 , 3-diisopropyl succinate, diisobutyl-2,3-bis (cyclohexylmethyl) succinate, diisobutyl-2,3-di-t-butyl succinate, diisobutyl-2,3-diisobutyl succinate, diisobutyl-2 , 3-Dineopentyl succinate, diisobutyl-2,3-diisopentyl succinate, diisobutyl-2,3- (1-trifluoromethylethyl) succinate, diisobutyl-2,3-tetradecyl succinate Diisobutyl-2,3-fluorenylsuccinate Diisobutyl-2-isopropyl-3-isobutyl succinate, diisobutyl-2-tert-butyl-3-isopropyl succinate, diisobutyl-2-isopropyl-3-cyclohexyl succinate, diisobutyl-2-isopentyl-3- Cyclohexyl succinate, diisobutyl-2-tetradecyl-3-cyclohexylmethyl succinate, diisobutyl-2-cyclohexyl-3-cyclopentyl succinate, dineopentyl-2,3-bis (trimethylsilyl) succinate, dineopentyl-2,2- sec-butyl-3-methyl succinate, dineopentyl-2- (3,3,3-trifluoropropyl) -3-methyl succinate, dineopentyl-2,3-bis (2-ethylbutyl) succinate, cine Pentyl-2,3-diethyl-2-isopropyl succinate, dineopentyl-2,3-diisopropyl-2-methyl succinate, dineopentyl-2,3-dicyclohexyl-2-methyl succinate, dineopentyl-2,3 -Dibenzyl succinate, dineopentyl-2,3-diisopropyl succinate, dineopentyl-2,3-bis (cyclohexylmethyl) succinate, dineopentyl-2,3-di-t-butyl succinate, dineopentyl-2, 3-diisobutyl succinate, dineopentyl-2,3-dineopentyl succinate, dineopentyl-2,3-diisopentyl succinate, dineopentyl-2,3- (1-trifluoromethylethyl) succinate, dineopentyl -2,3-tetradeci Succinate, dineopentyl-2,3-fluorenyl succinate, dineopentyl-2-isopropyl-3-isobutyl succinate, dineopentyl-2-tert-butyl-3-isopropyl succinate, dineopentyl-2-isopropyl-3- They are cyclohexyl succinate, dineopentyl-2-isopentyl-3-cyclohexyl succinate, dineopentyl-2-tetradecyl-3-cyclohexylmethyl succinate, and dineopentyl-2-cyclohexyl-3-cyclopentyl succinate.

Among the compounds of the formula (I), compounds in which some of the groups R _{3 to} R ₆ are bonded together to form a ring can also be preferably used. As such compounds, compounds listed in JP-T-2002-542347, for example, 1- (ethoxycarbonyl) -1- (ethoxyacetyl) -2,6-dimethylcyclohexane, 1- (ethoxycarbonyl) -1- ( Ethoxyacetyl) -2,5-monodimethylcyclopentane, 1- (ethoxycarbonyl) -1- (ethoxyacetylmethyl) -2 monomethylcyclohexane, 1- (ethoxycarbonyl) -1- (ethoxy (cyclohexyl) acetyl) cyclohexane Can be mentioned. In addition, for example, cyclic succinate compounds such as diisobutyl 3,6-dimethylcyclohexane-1,2-dicarboxylate and diisobutyl cyclohexane-1,2-dicarboxylate as disclosed in WO2009 / 069483 are also suitable. Can be used. As another example of the cyclic succinate compound, a compound disclosed in International Publication No. 2009/057747 is also preferable.

Of the compounds of formula (I), when the groups R _{3 to} R ₆ contain heteroatoms, the heteroatoms may be group 15 atoms including nitrogen and phosphorus atoms or group 16 atoms including oxygen and sulfur atoms. preferable. Examples of the compound in which the groups R _{3 to} R ₆ include a Group 15 atom include compounds disclosed in JP-A-2005-306910. On the other hand, examples of the compound in which the groups R _{3 to} R ₆ include a Group 16 atom include compounds disclosed in JP-A No. 2004-131537.

  In addition, an internal electron donor that gives a molecular weight distribution equivalent to that of the succinate compound may be used. Examples of such internal electron donors include diphenyl dicarboxylic acid esters described in JP2013-28704A, cyclohexene dicarboxylic acid esters described in JP2014-201602A, and JP2013-28705A. And didiol dibenzoate described in Japanese Patent No. 4959920, and 1,2-phenylene dibenzoate described in WO 2010/078494.

[(B) component: organoaluminum compound]
Examples of the organoaluminum compound (B) include the following.
Trialkylaluminum such as triethylaluminum, tributylaluminum;
Trialkenyl aluminum such as triisoprenyl aluminum:
Dialkylaluminum alkoxides such as diethylaluminum ethoxide and dibutylaluminum butoxide;
Alkylaluminum sesquialkoxides such as ethylaluminum sesquiethoxide and butylaluminum sesquibutoxide;
Partially halogenated alkylaluminums such as alkylaluminum dihalogenides such as ethylaluminum dichloride, propylaluminum dichloride, butylaluminum dibromide and the like;
Dialkylaluminum hydrides such as diethylaluminum hydride, dibutylaluminum hydride;
Partially hydrogenated alkylaluminums such as alkylaluminum dihydrides such as ethylaluminum dihydride, propylaluminum dihydride;
Partially alkoxylated and halogenated alkylaluminums such as ethylaluminum ethoxychloride, butylaluminum butoxychloride, ethylaluminum ethoxybromide.

[(C) component: electron donor compound]
The electron donor compound of component (C) is generally referred to as “external electron donor”. Such an electron donor compound is preferably an organosilicon compound. The following is mentioned as a preferable organosilicon compound.
Trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diisopropyldimethoxysilane, t-butylmethyldimethoxysilane, t-butylmethyldiethoxysilane, t-amylmethyldiethoxysilane, diphenyldimethoxysilane, phenylmethyl Dimethoxysilane, diphenyldiethoxysilane, bis o-tolyldimethoxysilane, bism-tolyldimethoxysilane, bisp-tolyldimethoxysilane, bisp-tolyldiethoxysilane, bisethylphenyldimethoxysilane, dicyclopentyldimethoxysilane, dicyclohexyldimethoxy Silane, cyclohexylmethyldimethoxysilane, cyclohexylmethyldiethoxysilane, ethyltrimethoxysilane, ethyl Riethoxysilane, vinyltrimethoxysilane, methyltrimethoxysilane, n-propyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, phenyltrimethoxysilane, γ-chloropropyltrimethoxysilane, methyltriethoxysilane, ethyl Triethoxysilane, vinyltriethoxysilane, t-butyltriethoxysilane, texyltrimethoxysilane, n-butyltriethoxysilane, iso-butyltriethoxysilane, phenyltriethoxysilane, γ-aminopropyltriethoxysilane, chloro Triethoxysilane, ethyltriisopropoxysilane, vinyltributoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, 2-norbornanetrimethoxy Lan, 2-norbornanetriethoxysilane, 2-norbornanemethyldimethoxysilane, ethyl silicate, butyl silicate, trimethylphenoxysilane, methyltriallyloxysilane, vinyltris (β-methoxyethoxysilane), vinyltriacetoxysilane, Dimethyltetraethoxydisiloxane.
Among them, ethyltriethoxysilane, n-propyltriethoxysilane, n-propyltrimethoxysilane, t-butyltriethoxysilane, t-butylmethyldimethoxysilane, t-butylmethyldiethoxysilane, t-butylethyldimethoxysilane, t-butylpropyldimethoxysilane, t-butylt-butoxydimethoxysilane, t-butyltrimethoxysilane, i-butyltrimethoxysilane, isobutylmethyldimethoxysilane, i-butylsec-butyldimethoxysilane, ethyl (perhydroisoquinoline 2- Yl) dimethoxysilane, bis (decahydroisoquinolin-2-yl) dimethoxysilane, tri (isopropenyloxy) phenylsilane, texyltrimethoxysilane, vinyltriethoxysilane, phenyltrie Xysilane, phenyltrimethoxysilane, vinyltributoxysilane, diphenyldimethoxysilane, diisopropyldimethoxysilane, diisobutyldimethoxysilane, i-butyli-propyldimethoxysilane, cyclopentyl t-butoxydimethoxysilane, dicyclopentyldimethoxysilane, cyclohexylmethyldimethoxysilane, Cyclohexyl i-butyldimethoxysilane, cyclopentyl i-butyldimethoxysilane, cyclopentylisopropyldimethoxysilane, di-sec-butyldimethoxysilane, diethylaminotriethoxysilane, tetraethoxysilane, tetramethoxysilane, isobutyltriethoxysilane, phenylmethyldimethoxysilane, Phenyltriethoxylane, bis p-tolyldimethoxy Silane, p-tolylmethyldimethoxysilane, dicyclohexyldimethoxysilane, cyclohexylethyldimethoxysilane, 2-norbornanetriethoxysilane, 2-norbornanemethyldimethoxysilane, diphenyldiethoxysilane, methyl (3,3,3-trifluoropropyl) dimethoxy Silane and ethyl silicate are preferred.

In the production of a polypropylene-based polymer, it is preferable to polymerize by bringing a raw material monomer into contact with the catalyst prepared as described above. At this time, it is preferable to first perform prepolymerization using the catalyst. Preliminary polymerization is a step of forming a polymer chain as a foothold for subsequent polymerization of raw material monomers on a solid catalyst component. The prepolymerization can be performed by a known method. The prepolymerization is usually performed at 40 ° C or lower, preferably 30 ° C or lower, more preferably 20 ° C or lower.
Next, a prepolymerized catalyst is introduced into the polymerization reaction system, and main polymerization of the raw material monomers is performed to produce a polypropylene polymer.

  The polypropylene polymer thus obtained by polymerization, the crystal nucleating agent, and other additives as necessary are stirred with a Henschel mixer, Brabender, etc., and then melt blended at 180 ° C. to 280 ° C. using an extruder. By doing so, the polypropylene composition of the present invention can be obtained. The addition of the crystal nucleating agent and other additives may be performed using a connected extruder after polymerization, residual monomer removal, and a drying step. In the present invention, a so-called master batch obtained by melt-kneading a high concentration crystal nucleating agent with a polypropylene polymer may be mixed with the polypropylene polymer at the time of sheet forming.

<Polypropylene sheet>
The polypropylene sheet of the present invention comprises the polypropylene composition of the present invention. The polypropylene sheet may be a single layer or a multilayer laminate. The thickness of the polypropylene sheet is preferably 150 to 3000 μm, and more preferably 150 to 2000 μm. If the thickness is less than 150 μm, the rigidity tends to be insufficient. If the rigidity is insufficient, it is not suitable for a sheet material used for food packaging or fiber packaging. When the thickness exceeds 3000 μm, the cost is simply increased, which is not realistic in the case of manufacturing a large amount at a low cost in the industry.

<Method for producing polypropylene sheet>
The method for producing the polypropylene sheet of the present invention is not particularly limited. For example, the unstretched sheet which consists of a polypropylene composition of this invention may be sufficient, and the sheet | seat which biaxially stretched this unstretched sheet may be sufficient.
The production process of the unstretched sheet and the biaxial stretching process can be performed using a known method.
The unstretched sheet can be produced by winding a resin melted by an extruder with a cooling roll. The melt extrusion method is preferably a T-die extrusion method. Examples of the cooling step include water cooling, air cooling, rolls, belts, and other generally known cooling methods, but it is preferable for the purpose of obtaining transparency with a small amount of crystal nucleating agent that the molten resin is uniformly and efficiently quenched. A belt method (Japanese Patent No. 4237275), a sleeve rubber roll method (Japanese Patent No. 4472018), a swing roll method (Japanese Patent No. 4701667), and the like may be used in combination. The molten resin temperature in the extruder is preferably 200 to 250 ° C, and the cooling roll temperature is preferably 20 to 90 ° C.
140-170 degreeC is preferable, as for the shaping | molding temperature at the time of biaxially stretching an unstretched sheet, 150-165 degreeC is more preferable, and 155-160 degreeC is further more preferable.

<Method for producing secondary molded body made of polypropylene sheet>
The polypropylene sheet of the present invention can be easily processed into a container or a tray by a known thermoforming method such as vacuum forming, vacuum pressure forming, hot plate forming or the like. The secondary molded product can be used as a lunch box, a side dish tray, an insulated container, and the like. The thickness of the secondary molded body is preferably 150 to 1000 μm, and more preferably 150 to 400 μm. If the thickness is less than 150 μm, the rigidity tends to be insufficient. If the rigidity is insufficient, it is not suitable for a sheet material used for food packaging or fiber packaging. If the thickness exceeds 1000 μm, the cost is simply increased, so that it is not practical in the case of manufacturing a large amount at a low cost in the industry.

Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.
<Measurement method / Evaluation method>
[Ethylene content in polypropylene polymer]
As for the ethylene content in the polypropylene-based polymer, JNM LA-400 ( ^13C resonance frequency 100 MHz) manufactured by JEOL Ltd. was used for a sample dissolved in a mixed solvent of 1,2,4-trichlorobenzene / deuterated benzene. It was calculated from the value measured by the ¹³ C-NMR method.

[Analysis of the final melting curve]
The final melting curve was analyzed using a differential thermal analyzer (Diamond DSC manufactured by PerkinElmer).
In the repeated annealing treatment, the measurement sample was held at 220 ° C. for 5 minutes, then cooled to 20 ° C. at 10 ° C./minute, held for 5 minutes, and then heated to 175 ° C. at 10 ° C./minute.
Next, after holding at 175 ° C. for 5 minutes, it was cooled to 20 ° C. at 10 ° C./min, held for 5 minutes, and heated to 170 ° C. at 10 ° C./min.
Thereafter, heating and cooling were repeated so that the maximum heating temperature was successively lowered by 5 ° C. Also in this case, the heating rate was 10 ° C./min, and the minimum temperature was 20 ° C.
The maximum heating temperature was set to 80 ° C. and held for 5 minutes, then cooled to 20 ° C. at 10 ° C./minute, held for 5 minutes, and the repeated annealing treatment was completed.
Subsequently, it was reheated to 200 ° C. at 10 ° C./min, and the final melting curve at that time was analyzed in the same manner as in ordinary differential thermal analysis.
In this way, a final melting curve in which the x-axis is temperature (° C.) and the y-axis is the endothermic amount associated with melting is obtained, and x ≦ 160 with respect to the total area surrounded by the final melting curve and the baseline. The ratio of the area surrounded by the final melting curve at (° C.), the baseline, and the straight line of x = 160 (° C.) is obtained, and the ratio of the enthalpy of melting at 160 ° C. or lower, that is, the melting temperature It was a ratio.
Similarly, the ratio of the area surrounded by the final melting curve, the baseline, and the straight line of x = 170 (° C.) at x ≧ 170 (° C.) with respect to the total area, and the ratio of the melting enthalpy at 170 ° C. or higher. That is, the proportion of the component having a melting temperature of 170 ° C. or higher was used.

[Rigidity]
The stiffness of the polypropylene sheet was measured according to JIS K7106. Using a stiffness tester (Taber Co., Ltd., TB-150), measurements were taken at room temperature (23 ° C.) in the take-up direction (MD) and its vertical direction (TD), and the average value thereof was determined. The higher the stiffness value, the better the rigidity.
[Haze]
The haze of the polypropylene sheet was measured in accordance with ISO 14782 using a haze meter (manufactured by Murakami Color Research Laboratory, HM-150). The smaller the haze value, the better the transparency.

[Production Example 1: Preparation of catalyst (S)]
A solid catalyst component was prepared according to the preparation method described in Examples of JP2011-500907A. Specifically, it is as follows.
In a 500 mL 4-neck round bottom flask purged with nitrogen, 250 mL of TiCl ₄ was introduced at 0 ° C. While stirring, 10.0 g of fine spherical MgCl ₂ .1.8 C ₂ H ₅ OH (produced according to the method described in Example 2 of USP-4,399,054, but operating at 3000 rpm instead of 10000 rpm) ) And 9.1 mmol of diethyl-2,3- (diisopropyl) succinate was added. The temperature was raised to 100 ° C. and held for 120 minutes. Next, stirring was stopped, the solid product was allowed to settle, and the supernatant liquid was siphoned off. The following procedure was then repeated twice: 250 mL of fresh TiCl ₄ was added and the mixture was allowed to react at 120 ° C. for 60 minutes and the supernatant was siphoned off. The solid was washed 6 times with anhydrous hexane (6 × 100 mL) at 60 ° C. to obtain a solid catalyst (1).
(Preliminary polymerization)
The solid catalyst (1) obtained above, triethylaluminum (TEAL), and diisopropyldimethoxysilane (DIPMS), the mass ratio of TEAL to the solid catalyst (1) is 11, and the mass ratio of TEAL / DIPMS is The amount of contact was 3 and contacted at 12 ° C. for 24 minutes. The obtained catalyst system was preliminarily polymerized by being held in liquid propylene in a suspended state at 20 ° C. for 5 minutes to obtain a catalyst (S).

[Production Example 2: Preparation of catalyst (P)]
A solid catalyst component was prepared by the method described in Example 1 of European Patent No. 6749991. The solid catalyst is obtained by supporting Ti and diisobutyl phthalate as an internal donor on MgCl ₂ by the method described in the above-mentioned patent publication.
(Preliminary polymerization)
The solid catalyst (2) obtained above and TEAL and cyclohexylmethyldimethoxysilane (CHMMS) in such an amount that the weight ratio of TEAL to the solid catalyst is 8 and the molar ratio of CHMMS / TEAL is 0.02. And contacted at -5 ° C for 5 minutes. The obtained catalyst system was preliminarily polymerized by being held in liquid propylene in a suspended state at 20 ° C. for 5 minutes to obtain a catalyst (P).

[Polymerization method (G): multistage polymerization method combining slurry method and gas phase polymerization method]
The first stage was a multistage polymerization process using a circulating liquid phase reactor, and the second stage was a fluidized bed gas phase reactor. A propylene homopolymer was produced by supplying catalyst, propylene and hydrogen to the first-stage reactor. Propylene, ethylene, and hydrogen were supplied to the second-stage reactor to obtain a polypropylene polymer composed of a propylene homopolymer and a propylene / ethylene random copolymer. The first stage polymerization temperature was 72 ° C., and the polymerization pressure was 3.0 MPa. The polymerization temperature in the second stage was 80 ° C. and the polymerization pressure was 1.7 MPa.

[Polymerization method (L): multistage polymerization method by slurry method]
In both the first and second stages, a multistage polymerization method was performed using a circulating liquid phase reactor. A propylene homopolymer was produced by supplying catalyst, propylene and hydrogen to the first-stage reactor. Propylene, ethylene, and hydrogen were supplied to the second-stage reactor to obtain a polypropylene polymer composed of a propylene homopolymer and a propylene / ethylene random copolymer. The first stage polymerization temperature was 72 ° C., and the polymerization pressure was 3.0 MPa. The polymerization temperature in the second stage was 66 ° C. and the polymerization pressure was 2.7 MPa.

[Polymerization method (L ′): Single-stage polymerization method by slurry method]
A single-stage polymerization process was carried out using a circulating liquid phase reactor. A catalyst, propylene and hydrogen were supplied to the reactor to obtain a propylene homopolymer, and further ethylene was supplied to obtain a propylene / ethylene random copolymer. The polymerization temperature was 72 ° C. and the polymerization pressure was 3.0 MPa.

[Examples 1-7, Comparative Examples 1-5]
A polymerization process was performed under the conditions shown in Table 1 to obtain a polypropylene polymer.
With respect to 100 parts by mass of the obtained polypropylene polymer, as a crystal nucleating agent, nonitol nucleating agent (manufactured by Milliken Japan, product name: Millad NX8000J) or phosphate ester nucleating agent (manufactured by ADEKA, product name: ADK STAB NA-21) is added so as to have the content shown in the table, and 0.24 parts by mass of an antioxidant (B225 manufactured by BASF) and 0.05 parts by mass of a neutralizing agent (calcium stearate). The resulting mixture was melt kneaded at 230 ° C. using an extruder to obtain a polypropylene composition.
In the obtained polypropylene composition, the ethylene content of the polypropylene polymer, Mw / Mn, the xylene insoluble content, the stereoregularity of the xylene insoluble content (mmmm), the MFR of the polypropylene composition, and the content of the crystal nucleating agent The results are shown in Table 1 (hereinafter the same).
Further, the final melting curve of the polypropylene polymer was analyzed, and the melting peak temperature, the proportion of the component having a melting temperature of 170 ° C. or higher, and the proportion of the component having a melting temperature of 160 ° C. or lower were measured. The results are shown in Table 1 (hereinafter the same).

(Evaluation of sheet)
Using the obtained polypropylene composition, a biaxially oriented sheet was produced as follows.
First, a sheet was prepared using a multilayer sheet molding machine (manufactured by Thermo Plastic Industry Co., Ltd.) provided with three extruders having a screw diameter of 25 mm and provided with a T-die capable of stacking three layers. More specifically, the polypropylene composition was melted at 230 ° C. using all three extruders. The T-die temperature of 300 mm width was set to 230 ° C., and both sides of the sheet were brought into close contact with the peripheral surface of the metal roll, thereby cooling the sheet and manufacturing an unstretched sheet having a predetermined thickness.
Using the obtained unstretched sheet, the rigidity and haze of the polypropylene sheet were measured by the above method. These results are shown in Table 1 (hereinafter the same).

[Example 8: Production of multilayer sheet]
In the sheet molding using the multilayer sheet molding machine, the material used in Example 1 (MFR = 3 g / 10 min) was used for the surface layer, and the material used in Example 3 (MFR = 9 g / 10) was used for the intermediate layer. Min) was used to produce an unstretched sheet having a thickness of 0.2 mm with two types and three layers having a layer ratio of 1: 5: 1 by coextrusion. Other steps are the same as those in the first embodiment. In Example 8, compared with Example 1, a material having a high MFR is used only for the intermediate layer, but this is an example assuming in-process recycling using a sheet end material as a recycled material in practice.
The rigidity and haze of the polypropylene sheet were measured by the above method. Also, sheet formability was evaluated. These results are shown in Table 1 (hereinafter the same).

As shown in Table 1, the polypropylene compositions of Examples 1 to 8 had good sheet formability, low haze, excellent transparency, and excellent rigidity.
Compared to these, Comparative Example 1 in which the amount of xylene insolubles in the polypropylene-based polymer, mmmm in xylene insolubles, and Mw / Mn is small is inferior in sheet rigidity, and Comparative Example 2 consisting only of propylene / ethylene random copolymer is In the melting curve by thermal analysis, the condition (B-ii) could not be satisfied, and the rigidity of the sheet was inferior.
Further, Comparative Example 3 in which the polypropylene polymer is a propylene homopolymer has poor sheet transparency, and Comparative Example 4 in which the ethylene content in the polypropylene polymer exceeds 0.5% by mass has poor sheet rigidity. .
In Comparative Example 5 in which the content of the crystal nucleating agent is 0.15 parts by mass, Example 1 in which the content of the crystal nucleating agent is 0.35 parts by mass, or the content of the crystal nucleating agent is 0.25 parts by mass. As compared with Example 5, the sheet rigidity (stiffness) and transparency were inferior.

Claims (4)

Propylene homopolymer 30-70% by mass and propylene / ethylene random copolymer 30-70% by mass, ethylene content 0.5% by mass or less, molecular weight distribution (Mw / Mn) 6-20, 25 ° C. The amount of xylene insolubles at 97 to 99% by mass, the stereoregularity (mmmm) of xylene insolubles from 97.5 to 99.5%, and heating and cooling are performed several times so that the maximum heating temperature is successively lowered. A polypropylene polymer in which a melting curve by thermal analysis when reheated after repeating satisfies the following conditions (Bi) to (B-iii):
And 0.18 to 0.5 parts by mass of a crystal nucleating agent with respect to 100 parts by mass of the polypropylene-based polymer,
A polypropylene composition having a melt flow rate of 1 to 10 g / 10 min.
(Bi) The melting peak temperature is 165 ° C. or higher.
(B-ii) The proportion of components having a melting temperature of 170 ° C. or higher is 10% or higher.
(B-iii) The proportion of components having a melting temperature of 160 ° C. or lower is 15% or more.   A polypropylene sheet comprising the polypropylene composition according to claim 1. A method for producing the polypropylene composition according to claim 1, comprising:
The polypropylene-based polymer is produced by a multi-stage polymerization method having two or more stages of polymerization steps continuously, or using a polymerizer having a gradient of one or both of monomer concentration and polymerization conditions,
A method for producing a polypropylene composition, comprising mixing the obtained polypropylene polymer and the crystal nucleating agent.   In the polymerization step, (A) a solid catalyst containing as an essential component an electron donor compound selected from magnesium, titanium, halogen, and a succinate compound; (B) an organoaluminum compound; and (C) an external electron donor The manufacturing method of the polypropylene composition of Claim 3 using the catalyst containing a compound.

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