JP5539789B2 - Propylene polymer for microporous film formation and use thereof - Google Patents

Description

  The present invention relates to a propylene polymer for forming a microporous film having a specific molecular weight structure and use thereof. Specifically, the present invention relates to an elution peak temperature measured by TREF and a propylene polymer for forming a microporous film having an elution integral amount in a specific range and its use.

  Microporous membranes formed from polymer materials are used in various applications such as medical and industrial filtration membranes, separation membranes, separators such as battery separators and capacitor separators.

  In particular, recently, the demand for secondary batteries as a power source for mobile phones, mobile personal computers and automobiles has increased, and the demand for battery separators has also increased. However, battery separators formed from conventional polymer materials have no material that satisfies all the required performance, and have the advantages and disadvantages depending on the type of raw material resin. Ultra high molecular weight polyethylene, which is the main material of separators at present, has a melting point of about 140 ° C and has limited heat resistance. On the other hand, in view of the popularization of batteries for automobiles in the future, the heat resistance of separators has been improved from the market. There are many voices requesting.

  In order to improve the heat resistance of battery separators, a technique for blending polypropylene (PP), which is a material having a high melting point, with ultrahigh molecular weight polyethylene has been studied. For example, Japanese Patent Laid-Open No. 5-331306 (Patent Document 1) discloses a composition of polypropylene and ultrahigh molecular weight polyethylene, characterized in that polypropylene forms a continuous layer, and is a microporous material having high heat resistance. A membrane has been reported. However, the evaluation result regarding strength is not disclosed. Moreover, it is known that polypropylene and polyethylene do not show compatibility, and it is expected that the strength may be low.

  As a microporous film made of a propylene polymer, for example, in Japanese Patent Application Laid-Open No. 2000-63551 (Patent Document 2), the number average molecular weight (Mn) is 60,000 or more, and the weight average molecular weight (Mw), which is an index of molecular weight distribution, A propylene polymer having a number average molecular weight quotient (Mw / Mn) of 7 or less is disclosed, and a separator excellent in piercing strength has been reported. However, it is well known that it is preferable that the molecular weight distribution is wide in view of moldability, and it is expected that the separator may be disadvantageous in this respect.

JP-A-5-331306 JP 2000-63551 A

  The present invention has been made under the circumstances as described above. That is, the present invention is a propylene polymer for forming a microporous film, which has a microporous shape, has high strength, and is expected to be excellent in moldability, and can provide a microporous film excellent in heat resistance and strength. It is another object of the present invention to provide an application for the same.

The propylene polymer for forming a microporous film according to the present invention satisfies the following requirements (1) to (4). (1) According to ASTM D1238E standard, the melt flow rate measured at 230 ° C. is 1 to 10 g / 10 min.
(2) Mesopentad fraction measured by ¹³ C-NMR (nuclear magnetic resonance method) is 94.0 to 99.5%.
(3) Melting | fusing point measured with the differential scanning calorimeter (DSC) is 150 to 167 degreeC. (4) The peak top temperature measured by TREF is 114 to 125 ° C., and the integrated amount of elution at 110 ° C. is 40 wt% or less.

The propylene polymer preferably satisfies the following requirement (5).
(5) The room temperature xylene soluble component content (CXS) is less than 4%.

The propylene polymer is
(I) a solid titanium catalyst component containing titanium, magnesium, halogen and a cyclic ester compound (a) specified by the following formula (1);
(II) It is preferably obtained using an organometallic compound component containing an element belonging to Group 1, Group 2, or Group 13 of the Periodic Table.

(In Formula (1), n is an integer of 5-10.

R ² and R ³ are each independently COOR ¹ or R, and at least one of R ² and R ³ is COOR ¹ . Single bonds in the cyclic skeleton (except for C ^a -C ^a bonds and C ^a -C ^b bonds when R ³ is R) may be replaced by double bonds.

R ¹ is each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms.

  A plurality of Rs are each independently an atom or group selected from a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, a nitrogen-containing group, an oxygen-containing group, a phosphorus-containing group, a halogen-containing group and a silicon-containing group. And may be bonded to each other to form a ring, but at least one R is not a hydrogen atom.

A double bond may be contained in the ring skeleton formed by bonding R to each other, and when the ring skeleton contains two or more C ^a bonded with COOR ¹ , The number of carbon atoms constituting the skeleton is 5 to 10. )
Moreover, the propylene polymer for forming a microporous membrane according to the present invention can be suitably used for a separator, a filtration membrane, and a separation membrane.

  The separator is more preferably a battery separator or a capacitor separator. The battery separator is particularly preferably a lithium ion secondary battery separator. More preferably, the separation membrane is a medical separation membrane.

  Since the propylene polymer for forming a microporous film of the present invention satisfies specific requirements, it is excellent in heat resistance and strength.

  Hereinafter, the propylene polymer for forming a microporous film according to the present invention (hereinafter also referred to as “the propylene polymer of the present invention”) will be specifically described.

[Propylene polymer for forming microporous film]
The propylene polymer of the present invention satisfies the following requirements (1) to (4).
(1) According to ASTM D1238E standard, the melt flow rate measured at 230 ° C. is 1 to 10 g / 10 min.
(2) Mesopentad fraction measured by ¹³ C-NMR (nuclear magnetic resonance method) is 94.0 to 99.5%.
(3) The melting point measured by a differential scanning calorimeter (DSC) is 150 ° C to 167 ° C. (4) The peak top temperature measured by TREF is 114 to 125 ° C., and the integrated amount of elution at 110 ° C. is 40 wt% or less.

  It is preferable that the propylene polymer of the present invention further satisfies the following requirement (5).

  (5) The room temperature xylene soluble component content (CXS) is less than 4%.

<< Requirement (1) >>
The propylene polymer of the present invention has a melt flow rate of 1 to 10 g / 10 min measured at 230 ° C. according to the ASTM D1238E standard. A more preferred lower limit is 1 g / 10 minutes, and even more preferably 2 g / 10 minutes. On the other hand, the preferred upper limit is 8 g / 10 minutes, more preferably 5
g / 10 minutes.

  When the melt flow rate is lower than 1 g / 10, the moldability, for example, the molding speed may be lowered and the productivity may be lowered. On the other hand, if the melt flow rate exceeds 10 g / 10, the strength of the resulting microporous membrane may be lowered, draw-down during molding, and stretchability may be reduced.

  It is known that the melt flow rate (MFR) depends on the molecular weight of the polymer, and the molecular weight of the propylene polymer is determined by the composition ratio of hydrogen and propylene in the polymerization reaction system. Therefore, the MFR of the propylene polymer can be increased or decreased by adjusting the hydrogen / propylene ratio in the polymerization reaction system.

<< Requirement (2) >>
The propylene polymer of the present invention has a mesopentad fraction measured by ¹³ C-NMR (nuclear magnetic resonance method) of 94.0 to 99.5%. More preferably, it is 96.0-99.5%, More preferably, it is 97.0-99.5%.

The mesopentad fraction (mmmm fraction) indicates the proportion of pentad isotactic structure in the molecular chain, and the propylene structural unit is located at the center of a chain having five mesostructured propylene monomer units. Is a fraction of. A propylene polymer satisfying such requirements is obtained by polymerizing propylene with an olefin polymerization catalyst including a known solid titanium catalyst component and an organometallic compound catalyst component, which will be described later, and an electron donor used as necessary. Can be obtained.

  When the mesopentad fraction of the propylene polymer is within the above range, the resulting propylene polymer for forming a microporous film is excellent in heat resistance and strength.

  The propylene polymer having a mmmm fraction in the above range can be produced by appropriately selecting a known catalyst described later.

<< Requirement (3) >>
The propylene polymer of the present invention has a melting point measured by DSC in the range of 150 to 167 ° C. Preferably it is 160-167 degreeC, More preferably, it is 162-167 degreeC.

  When the melting point measured by DSC of the propylene polymer is less than 150 ° C., the heat resistance may be insufficient. On the other hand, when the melting point exceeds 167 ° C., microporosity may be insufficient due to reasons such as the crystallinity being too high.

  The propylene polymer having a melting point in the above range can be produced by appropriately selecting a known catalyst described later.

<< Requirement (4) >>
The propylene polymer of the present invention has a peak top temperature measured by TREF of 114 to 125 ° C., and an elution integrated amount at 110 ° C. of 40 wt% or less.

  Since TREF (Temperature Rising Elution Fractionation) can separate polymer chains having different crystallinity, branching degree, copolymerization degree, etc., information on the composition distribution of the polymer sample can be obtained.

  The peak top temperature calculated | required by a TREF measurement is 114-125 degreeC, Preferably it is 115-123 degreeC. When the peak temperature is within this range, it is preferable in that the heat shrinkage rate is small.

  According to TREF measurement, the integrated amount of elution up to 110 ° C. is 40 wt% or less, preferably 36 wt% or less. Since components that elute at less than 110 ° C. have a relatively low crystallinity, when it exceeds 40 wt%, the heat shrinkage rate increases, and the pores of the microporous membrane may not maintain the desired shape.

  A propylene polymer having a peak top temperature measured by TREF and an integrated amount of elution at 110 ° C. in the above ranges can be produced by appropriately selecting a known catalyst described later.

<< Requirement (5) >>
The propylene polymer of the present invention preferably satisfies the following requirement (5).

  (5) The room temperature xylene soluble component content (CXS) is less than 4%.

This room temperature xylene-soluble component is a component having mainly low stereoregularity and a low molecular weight, and is mainly composed of a rubber-like adhesive component. If such a component is less than 4%, blocking of the resulting microporous membrane, blockage of micropores and the like are unlikely to occur. It is also preferable for forming a homogeneous and strong crystal structure.

(Microporous membrane)
The microporous membrane refers to a polymer membrane having a large number of micropores of about 0.3 to 1.5 μm. In the present invention, the Gurley permeability measured in accordance with JIS P8117 is in the range of 200 to 800. The membrane is defined as a microporous membrane.

(Method for producing propylene polymer for forming microporous film)
Hereinafter, the manufacturing method of the propylene polymer for microporous film formation is demonstrated.

The method for producing a propylene polymer of the present invention is not limited as long as the propylene homopolymer satisfies the requirements (1) to (4), preferably (1) to (5). Is preferably a method of polymerizing propylene in the presence of a known olefin polymerization catalyst containing a solid titanium catalyst component. Examples of the solid titanium catalyst component include (I) a solid titanium catalyst component containing magnesium, titanium, halogen and an electron donor, (II) an organometallic compound catalyst component, and (III) an alkoxysilane. And an organic donor compound represented by an organosilicon compound or a specific polyether compound. Specifically, Japanese Patent No. 2723137, Japanese Patent Laid-Open No. 4-218507, Japanese Patent No. 2774160, Japanese Patent No. 2776914, International Publication No. 2006/77945, International Publication No. 2008/10459, International Publication No. 2004. / 16662 pamphlet etc. are mentioned.

  The solid titanium catalyst component (I) can be prepared by contacting a magnesium compound (a-1), a titanium compound (a-2) and an electron donor (a-3).

  Examples of the magnesium compound (a-1) include a magnesium compound having a reducing ability such as a magnesium compound having a magnesium-carbon bond or a magnesium-hydrogen bond, and a magnesium halide, an alkoxymagnesium halide, an allyloxymagnesium halide, an alkoxymagnesium, Examples include magnesium compounds having no reducing ability, such as allyloxymagnesium and magnesium carboxylates.

  In the preparation of the solid titanium catalyst component (I), for example, a tetravalent titanium compound represented by the following formula (3) is preferably used as the titanium compound (a-2).

Ti (OR) _g X _4-g (3)
(In Formula (3), R is a hydrocarbon group, X is a halogen atom, and 0 ≦ g ≦ 4.)
Specifically, titanium tetrahalides such as TiCl ₄ , TiBr ₄ , and TiI ₄ ; Ti (OCH ₃ ) Cl ₃ , Ti (OC ₂ H ₅ ) Cl ₃ , Ti (On-C ₄ H ₉ ) Cl ₃ , Ti (OC ₂ H ₅ ) Br ₃ , Ti (O-iso-C ₄ H ₉ ) Br ₃ and other trihalogenated alkoxytitanium; Ti (OCH ₃ ) ₂ Cl ₂ , Ti (OC ₂ H ₅ ) ₂ Cl _{2, Ti (O-n-} C 4 H 9) 2 Cl 2, Ti (OC 2 H 5) 2 dihalogenated dialkoxy titanium, such as _{Br 2; Ti (OCH 3)} 3 Cl, Ti (OC 2 H 5) ₃ Cl, T
_{i (O-n-C 4} H 9) 3 Cl, Ti (OC 2 H 5) monohalide trialkoxy titanium such as _{3 Br; Ti (OCH 3)} 4, Ti (OC 2 H 5) 4, Ti ( _{O-n-C 4 H 9} ) 4, Ti (O-iso-
And tetraalkoxytitanium such as C ₄ H ₉ ) ₄ and Ti (O-2-ethylhexyl) ₄ .

Examples of the electron donor (a-3) used in the preparation of the solid titanium catalyst component (I) include alcohols, phenols, ketones, aldehydes, esters of organic acids or inorganic acids, organic acid halides, and the above polyethers. And ether, acid amide, acid anhydride, ammonia, amine, nitrile, isocyanate, nitrogen-containing cyclic compound, oxygen-containing cyclic compound and the like. Among these, preferred examples include aromatic polyester compounds having phthalic acid esters as representative examples, aliphatic polyesters having succinic acid esters having substituents as representative examples, and alicyclic polyesters to be described later, and the above polyethers. I can do it. These compounds may be used in combination of two or more.

  In the present invention, the electron donor (a-3) preferably used includes a cyclic ester compound specified by the following formula (1). Moreover, the cyclic ester compound specified by following formula (2) may be included.

  In Formula (1), n is an integer of 5-10.

R ² and R ³ are each independently COOR ¹ or R, and at least one of R ² and R ³ is COOR ¹ .

Single bonds in the cyclic skeleton (except for C ^a -C ^a bonds and C ^a -C ^b bonds when R ³ is R) may be replaced by double bonds.

R ¹ is each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms.

  A plurality of Rs are each independently an atom or group selected from a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, a nitrogen-containing group, an oxygen-containing group, a phosphorus-containing group, a halogen-containing group and a silicon-containing group. And may be bonded to each other to form a ring, but at least one R is not a hydrogen atom.

A double bond may be contained in the ring skeleton formed by bonding R to each other, and when the ring skeleton contains two or more C ^a bonded with COOR ¹ , The number of carbon atoms constituting the skeleton is 5 to 10.

  In Formula (2), n is an integer of 5-10.

R ⁴ and R ⁵ are each independently COOR ¹ or a hydrogen atom, and at least one of R ⁴ and R ⁵ is COOR ¹ . R ¹ is each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms. A single bond in the cyclic skeleton (C ^a -C ^a bond, and C ^a -C ^b when R ⁵ is R ⁾
May be replaced with a double bond.

  In the formula (1), it is preferable that all the bonds between carbon atoms in the cyclic skeleton are single bonds.

Among the cyclic ester compounds represented by formula (1)
Diisobutyl 3,6-dimethylcyclohexane-1,2-dicarboxylate,
Di-n-hexyl 3,6-dimethylcyclohexane-1,2-dicarboxylate,
Di-n-octyl 3,6-dimethylcyclohexane-1,2-dicarboxylate,
3-methyl-6-ethylcyclohexane-1,2-dicarboxylate diisobutyl,
Di-n-hexyl 3-methyl-6-ethylcyclohexane-1,2-dicarboxylate,
Di-n-octyl 3-methyl-6-ethylcyclohexane-1,2-dicarboxylate,
3-methyl-6-n-propylcyclohexane-1,2-dicarboxylate diisobutyl,
3-methyl-6-n-propylcyclohexane-1,2-dicarboxylate di-n-hexyl,
Di-n-octyl 3-methyl-6-n-propylcyclohexane-1,2-dicarboxylate,
Diisobutyl 3,6-diethylcyclohexane-1,2-dicarboxylate,
Di-n-hexyl 3,6-diethylcyclohexane-1,2-dicarboxylate,
Particularly preferred is di n-octyl 3,6-diethylcyclohexane-1,2-dicarboxylate.

Among the compounds represented by formula (2), diisobutylcyclohexane-1,2-dicarboxylate,
Cyclohexan-1,2-dicarboxylic acid dihexyl,
Cyclohexane-1,2-dicarboxylate diheptyl,
Dioctyl cyclohexane-1,2-dicarboxylate,
Cyclohexane-1,2-dicarboxylate di-2-ethylhexyl,
Is particularly preferred.

  When contacting the magnesium compound (a-1), titanium compound (a-2) and electron donor (a-3) as described above, other reaction reagents such as silicon, phosphorus, and aluminum are allowed to coexist. In addition, the carrier-supported solid titanium catalyst component (I) can be prepared using a carrier.

The solid titanium catalyst component (I) can be prepared by employing any method including a known method, but a few examples will be briefly described below.
(1) After a hydrocarbon solution of an adduct of an alcohol or metal acid ester or the like and a magnesium compound (a-1) is contact-reacted with a titanium compound (a-2) or an organometallic compound to precipitate a solid, Or the method of making it contact-react with a titanium compound (a-2), making it precipitate.
(2) Contacting and reacting the magnesium compound (a-1), alcohol, ester, and the like and the solid adduct with the titanium compound (a-2) or the organometallic compound, the titanium compound (a-2) is contact-reacted. How to make.
(3) A method in which a titanium compound (a-2) and an electron donor (a-3) are contact-reacted with a contact product between an inorganic carrier and an organomagnesium compound (a-1). At this time, the contact product may be previously contacted with the halogen-containing compound and / or the organometallic compound.
(4) Any of the above methods comprising a step carried out in the presence of an aromatic halogenated hydrocarbon or the like.
As the organometallic compound catalyst component (II), those containing a metal selected from Group 1, Group 2 and Group 13 of the periodic table are preferable. Specifically, organoaluminum as shown below Compounds, complex alkyl compounds of Group I metals and aluminum, and organometallic compounds of Group II metals.

Formula R ¹ _m Al (OR ² ) _n H _p X _q
(In the formula, R ¹ and R ² are hydrocarbon groups usually containing 1 to 15 carbon atoms, preferably 1 to 4 carbon atoms, which may be the same or different from each other. X represents a halogen atom, (0 <m ≦ 3, n is 0 ≦ n <3, p is 0 ≦ p <3, q is a number 0 ≦ q <3, and m + n + p + q = 3)
The organoaluminum compound (b-1) shown by these.

Formula M ¹ AlR ¹ ₄
(Wherein M ¹ is Li, Na or K, and R ¹ is the same as above.)
A complex alkylated product of a Group 1 metal and aluminum represented by (b-2).

Formula R ¹ R ² M ²
(Wherein R ¹ and R ² are the same as above, and M ² is Mg, Zn or Cd.)
A dialkyl compound (b-3) of Group 2 or Group 13 represented by:

Examples of the organoaluminum compound (b-1) include R ¹ _m Al (OR ² ) _3-m
(Wherein R ¹ and R ² are as defined above, and m is preferably a number of 1.5 ≦ m ≦ 3),
R ¹ _m AlX _3-m
(R ¹ is the same as above, X is halogen, and m is preferably 0 <m <3.)
A compound represented by
R ¹ _m AlH _3-m
(R ¹ is the same as above, and m is preferably 2 ≦ m <3.)
A compound represented by
R ¹ _m Al (OR ² ) _n X _q
(R ¹ and R ² are as defined above, X is halogen, 0 <m ≦ 3, 0 ≦ n <3, 0 ≦ q <
3 and m + n + q = 3. )
And the like.

Specific examples of the organosilicon compound catalyst component (III) include an organosilicon compound represented by the following formula (4).

SiR ³ R ⁴ _a (OR ⁵ ) _3-a (4)
(In the formula (4), a is 0, 1 or 2, and R ³ is a group consisting of a cyclopentyl group, a cyclopentenyl group, a cyclopentadienyl group, an isopropyl group, a t-butyl group, a dialkylamino group and derivatives thereof. Selected groups, R ⁴ and R ⁵ are hydrocarbon groups.)
In the formula (4), preferred as R ³ are cyclopentyl group, 2-methylcyclopentyl group, 3-methylcyclopentyl group, 2-ethylcyclopentyl group, 3-propylcyclopentyl group, 3-isopropylcyclopentyl group, 3-butyl. Cyclopentyl group, 3-tert-butylcyclopentyl group, 2,2-dimethylcyclopentyl group, 2,3-dimethylcyclopentyl group, 2,5-dimethylcyclopentyl group, 2,2,5-trimethylcyclopentyl group, 2,3,4 , 5-tetramethylcyclopentyl group, 2,2,5,5-tetramethylcyclopentyl group, 1-cyclopentylpropyl group, cyclopentyl group such as 1-methyl-1-cyclopentylethyl group or derivatives thereof; cyclopentenyl group, 2- Cyclopentenyl group, 3-cyclopentenyl Group, 2-methyl-1-cyclopentenyl group, 2-methyl-3-cyclopentenyl group, 3-methyl-3-cyclopentenyl group, 2-ethyl-3-cyclopentenyl group, 2,2-dimethyl-3 -Cyclopentenyl group, 2,5-dimethyl-3-cyclopentenyl group, 2,3,4,5-tetramethyl-3-cyclopentenyl group, 2,2,5,5-tetramethyl-3-cyclopentenyl group A cyclopentenyl group or a derivative thereof such as 1,3-cyclopentadienyl group, 2,4-cyclopentadienyl group, 1,4-cyclopentadienyl group, 2-methyl-1,3-cyclopentadiene Enyl group, 2-methyl-2,4-cyclopentadienyl group, 3-methyl-2,4-cyclopentadienyl group, 2-ethyl-2,4-cyclopentadienyl group, 2,2-dimethyl -2,4-cyclope Tadienyl group, 2,3-dimethyl-2,4-cyclopentadienyl group, 2,5-dimethyl-2,4-cyclopentadienyl group, 2,3,4,5-tetramethyl-2,4- Examples include cyclopentadienyl groups such as cyclopentadienyl groups or derivatives thereof, and bulky substituents such as isopropyl groups, t-butyl groups, and s-butyl groups. More preferred are a cyclopentyl group and an isopropyl group, and particularly preferred is a cyclopentyl group.

In the formula (4), specific examples of the hydrocarbon groups represented by R ⁴ and R ⁵ include hydrocarbon groups such as alkyl groups, cycloalkyl groups, aryl groups, and aralkyl groups in addition to the above substituents. be able to. When two or more R ⁴ or R ⁵ are present, R ⁴ or R ⁵ may be the same or different, and R ⁴ and R ⁵ may be the same or different. In the formula (4), R ³ and R ⁴ may be cross-linked with an alkylene group or the like.

  Preferred examples of the polyether compound include polyether compounds that are compounds having two or more ether bonds via a plurality of carbon atoms.

Among these polyether compounds, 1,3-diethers are preferred, and in particular, 2-isopropyl-2-isobutyl-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2-isopropyl 2-Isopentyl-1,3-dimethoxypropane, 2,2-dicyclohexyl-1,3-dimethoxypropane, and 2,2-bis (cyclohexylmethyl) 1,3-dimethoxypropane are preferred.

  These compounds can be used alone or in combination of two or more.

When performing polymerization of propylene using a catalyst comprising the solid titanium catalyst component (I), organometallic compound catalyst component (II), and organosilicon compound catalyst component (III) as described above, pre-polymerization is performed in advance. You can also. In the prepolymerization, the olefin is polymerized in the presence of the solid titanium catalyst component (I), the organometallic compound catalyst component (II), and, if necessary, the organosilicon compound catalyst component (III).

As the prepolymerized olefin, for example, an α-olefin having 2 to 8 carbon atoms can be used. Specifically, linear olefins such as ethylene, propylene, 1-butene and 1-octene; 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4- Methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-
Hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-
Olefin having a branched structure such as 1-hexene can be used. These may be copolymerized. In order to increase the crystallinity of the resulting propylene polymer, it may be preferable to use bulky olefins such as 3-methyl-1-butene and 3-methyl-1-pentene.

  The prepolymerization is desirably performed so that about 0.1 to 1000 g, preferably about 0.3 to 500 g of a polymer is produced per 1 g of the solid titanium catalyst component (I). If the amount of prepolymerization is too large, the production efficiency of the polymer in the main polymerization may decrease. In the prepolymerization, the catalyst can be used at a considerably higher concentration than the catalyst concentration in the system in the main polymerization.

In the main polymerization, the solid titanium catalyst component (I) (or the prepolymerized catalyst) is converted into titanium atoms per liter of polymerization volume of about 0.0001 to 50 mmol, preferably about 0.001 to 10 mmol. It is desirable to use in quantity. The organometallic compound catalyst component (II) is desirably used in an amount of about 1 to 2000 mol, preferably about 2 to 500 mol, based on 1 mol of titanium atom in the polymerization system. The organosilicon compound catalyst component (III) is desirably used in an amount of about 0.001 to 50 moles, preferably about 0.01 to 20 moles per mole of metal atoms of the organometallic compound catalyst component (II).

  The polymerization may be performed by any of a gas phase polymerization method, a liquid polymerization method such as a solution polymerization method and a suspension polymerization method, and each stage may be performed by a separate method. Moreover, you may carry out by any system of a continuous type and a semi-continuous type, and you may divide each stage into several polymerizers, for example, 2-10 polymerizers.

  As the polymerization medium, inert hydrocarbons may be used, and liquid propylene may be used as the polymerization medium. The polymerization conditions in each stage are such that the polymerization temperature is in the range of about −50 to + 200 ° C., preferably about 20 to 100 ° C., and the polymerization pressure is normal pressure to 10 MPa (gauge pressure), preferably about 0.2 to 5 MPa. It is appropriately selected within the range of (gauge pressure).

  After completion of the polymerization, a propylene polymer is obtained as a powder by performing post-treatment steps such as a known catalyst deactivation treatment step, a catalyst residue removal step, and a drying step as necessary.

(Other ingredients)
When producing a microporous film from the propylene polymer of the present invention, a propylene polymer composition may be prepared by blending at least one material selected from the group consisting of a plasticizer, polyethylene and inorganic powder. preferable.

-Polyolefins other than polypropylene The propylene polymer of the present invention may be blended with polyethylene for the purpose of imparting functions such as shutdown characteristics, for example, as long as the object of the present invention is not violated.

The polyethylene has a density of 925 to 970 kg / m ³ , preferably 930 to 965.
kg / m ³ of polyethylene.

  The intrinsic viscosity [η] measured using a decalin solution of polyethylene is preferably 2 to 40 dl / g, more preferably 3 to 40 dl / g.

  The blending amount of polyethylene in the propylene polymer fat composition containing the propylene polymer and polyethylene varies depending on the properties to be imparted, but is usually 1 to 99% by mass, preferably 10 to 95% by mass.

-Plasticizer The propylene polymer of this invention may mix | blend a plasticizer in order to adjust the shape and quantity of a hole.

  The plasticizer is a liquid solvent at room temperature, nonane, decane, decalin, paraxylene, liquid paraffin and other aliphatic, cycloaliphatic or aromatic hydrocarbons, and mineral oil fractions with boiling points corresponding to these, room temperature Examples of solid solvents include stearyl alcohol and paraffin wax. Among these, a solvent which is liquid at room temperature is preferable, and liquid paraffin is particularly preferable.

-Inorganic powder The propylene polymer of this invention may mix | blend inorganic powder in order to adjust the shape and quantity of a hole, and heat resistance.

  Examples of the inorganic powder include talc, clay, calcium carbonate, mica, silicates, carbonates, glass fibers, carbon fibers, and oxides and nitrides of metals such as silicon, aluminum, and titanium. Among these, metal oxides and nitrides are preferable, and silica powder is particularly preferable. The average particle size of the inorganic powder is desirably 0.001 to 10 μm, preferably 0.01 to 5 μm. Inorganic powder can be used individually by 1 type, and can also be used in combination of 2 or more type. The compounding amount of the inorganic powder is 1 to 80 parts by weight, preferably 10 to 60 parts by weight.

(Preparation method of propylene polymer for forming microporous film)
As a method for preparing the propylene polymer composition, various known methods can be used. For example, a method of kneading the various components described above using a normal kneading apparatus such as a Henschel mixer, a ribbon blender, or a Banbury mixer can be mentioned. The melt-kneading and pelletizing are performed by melt-kneading at 170 to 280 ° C., preferably 190 to 250 ° C., using an ordinary single-screw extruder or twin-screw extruder, Brabender or roll, and pelletizing. Alternatively, it can be directly formed into a sheet or film for a microporous membrane by a conventionally known technique without pelletizing.

(Use)
The propylene polymer of the present invention is preferably used in one type selected from the group consisting of a separator, a filtration membrane, a separation membrane and a filter.

  The separator is more preferably a battery separator or a capacitor separator, and the battery separator is particularly preferably a lithium ion secondary battery separator. More preferably, the separation membrane is a medical separation membrane.

(Microporous membrane)
From the propylene polymer of the present invention, a microporous membrane having excellent heat resistance and strength can be suitably produced.

The method for producing the microporous membrane is as follows:
(1) a step of individually melt-kneading the above-mentioned propylene polymer or each component;
(2) a step of extruding from a die lip and cooling to form a sheet or film;
(3) a step of stretching the sheet or film in at least a uniaxial direction;
(4) a step of extracting and removing the plasticizer as required,
(5) The process of drying the obtained film | membrane is included. In any case, a conventionally known technique can be used.

  In (1), a twin screw extruder is desirable because sufficient melt kneading is performed.

  In (2), a sheet die lip having a rectangular base shape is desirable, but a cylindrical inflation die lip or the like can also be used.

  In (3), it is desirable to stretch to a surface magnification of 2 to 100 times in a range of a stretching temperature of 20 to 160 ° C. by a tenter method or a roll method. Stretching can also be performed twice before and after the steps (4) and (5).

  In (4), it is desirable to use a solvent which is a poor solvent for the polyolefin resin and the inorganic powder and a good solvent for the plasticizer and has a boiling point lower than the melting point of the polyolefin microporous membrane. Examples include hydrocarbons such as n-hexane and cyclohexane, halogenated hydrocarbons such as methylene chloride and carbon tetrachloride, alcohols such as ethanol and isopropanol, ethers such as diethyl ether, and ketones such as acetone. It is done.

  In (5), a heat drying method, an air drying method, or the like is used. Addition of additives such as conventionally known nucleating agents (α crystal nucleating agents such as phosphate ester metal salts and sorbitol compounds, and β crystal nucleating agents such as amide compounds), heat treatment of films, and cross-linking as necessary Processes such as treatment, surface treatment, and hydrophilization treatment may be performed. For the purpose of providing a shutdown function, for example, the propylene polymer of the present invention is blended with a resin having a lower melting point than that of the propylene polymer of the present invention (including the above polyethylene), multilayered, and further provided with heat resistance. Blending with a resin having a melting point higher than that of the coalescence or multilayering may be performed.

EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.
(polypropylene)
Resins (PP-1, PP-2) of Examples 1 and 2 were prepared according to Example 1 and Comparative Example 1 of JP-A-2009-57473.

  The polypropylene resin (PP-3) used in Comparative Example 1 was prepared as follows.

(1) Preparation of Solid Titanium Catalyst Component 952 g of anhydrous magnesium chloride, 4420 ml of decane and 3906 g of 2-ethylhexyl alcohol were heated at 130 ° C. for 2 hours to obtain a homogeneous solution. To this solution, 213 g of phthalic anhydride was added, and further stirred and mixed at 130 ° C. for 1 hour to dissolve phthalic anhydride.

  After cooling the homogeneous solution thus obtained to 23 ° C., 750 ml of this homogeneous solution was dropped into 2000 ml of titanium tetrachloride maintained at −20 ° C. over 1 hour. After the dropwise addition, the temperature of the resulting mixture was raised to 110 ° C. over 4 hours. When the temperature reached 110 ° C., 52.2 g of diisobutyl phthalate (DIBP) was added, and the mixture was stirred at the same temperature for 2 hours. Held on. Subsequently, the solid part was collected by hot filtration, and the solid part was resuspended in 2750 ml of titanium tetrachloride, and then heated again at 110 ° C. for 2 hours.

  After the heating, the solid part was again collected by hot filtration, and washed with decane and hexane at 110 ° C. until no titanium compound was detected in the washing solution.

  The solid titanium catalyst component prepared as described above was stored as a hexane slurry. A part of the catalyst was dried to examine the catalyst composition. The solid titanium catalyst component contained 2% by weight of titanium, 57% by weight of chlorine, 21% by weight of magnesium and 20% by weight of DIBP.

(2) Production of pre-polymerization catalyst 120 g of transition metal catalyst component, 20.5 mL of triethylaluminum, and 120 L of heptane were inserted into an autoclave equipped with a stirrer with an internal volume of 200 L. It was made to react. After completion of the polymerization, the solid component was precipitated, and the supernatant was removed and washed with heptane twice. The obtained prepolymerization catalyst was resuspended in purified heptane and adjusted with heptane so that the transition metal catalyst component concentration was 1 g / L. This prepolymerization catalyst contained 6 g of polypropylene per 1 g of the transition metal catalyst component.

(3) Main polymerization In a vessel polymerization vessel with an internal volume of 100 L, 110 kg / hour of propylene, 1.1 g / hour of the catalyst slurry produced in (2) as a transition metal catalyst component, 5.8 mL / hour of triethylaluminum Then, dicyclopentyldimethoxysilane (2.1 mL / hour) and ethylene (0.3 kg / hour) were continuously supplied, and hydrogen was supplied so that the hydrogen concentration in the gas phase was 0.8 mol%. Polymerization was carried out at a polymerization temperature of 73 ° C. and a pressure of 3.2 MPa / G.

  The obtained slurry was sent to a vessel polymerization vessel equipped with a stirrer having an internal volume of 1000 L and further polymerized. To the polymerization vessel, propylene was supplied at 30 kg / hour, ethylene was supplied at 0.4 kg / hour, and hydrogen was supplied so that the hydrogen concentration in the gas phase was 1.5 mol%. Polymerization was performed at a polymerization temperature of 71 ° C. and a pressure of 3.1 MPa / G.

  The obtained slurry was sent to a vessel polymerization vessel equipped with a stirrer having an internal volume of 500 L and further polymerized. Propylene was supplied to the polymerization vessel at 46 kg / hour, ethylene was supplied at 0.3 kg / hour, and hydrogen was supplied so that the hydrogen concentration in the gas phase was 1.5 mol%. Polymerization was performed at a polymerization temperature of 69 ° C. and a pressure of 3.0 MPa / G.

  The resulting slurry was deactivated and then sent to a liquid propylene washing tank to wash the propylene polymer powder.

  After vaporizing the resulting slurry, gas-solid separation was performed to obtain a propylene polymer. The resulting propylene polymer was introduced into a conical dryer and vacuum dried at 80 ° C. Next, 35.9 grams of pure water and 0.63 liters of propylene oxide were added to 100 kilograms of the product, followed by dechlorination treatment at 90 ° C. for 2 hours, followed by vacuum drying at 80 ° C. to produce propylene polymer powder. Got. The obtained polymer powder was pelletized by the same method as in Example 1.

  The measuring method of the physical property in an Example and a comparative example is as follows.

(Melt flow rate)
As described above, the measurement was performed under the temperature condition of 230 ° C. according to the ASTM D1238E standard.

(Mesopentad fraction)
Mesopentad fraction [mmmm] Zambelli et al., Macromolecules, 8, 687 (1975). The value is determined by 13C-NMR under the following conditions, and mesopentad fraction = (peak area at 21.7 ppm) / ( Peak area at 19 to 23 ppm).

Type JNM-Lambada400 (manufactured by JEOL Ltd.)
Resolution 400MHz
Measurement temperature 125 ℃
Solvent 1,2,4-trichlorobenzene / deuterated benzene = 7/4
Pulse width 7.8μsec (45 ° pulse)
Pulse interval 5 sec
Integration count 2000 times Shift standard TMS = 0ppm
Mode Single pulse broadband decoupling (melting point (Tm))
The measurement was performed as follows using a differential scanning calorimeter (DSC, manufactured by PerkinElmer). Here, the endothermic peak at the third step was defined as the melting point (Tm).

<Create sample sheet>
The sample was sandwiched between aluminum foils and press-molded under the following conditions using a mold (thickness: 0.2 mm).

Molding temperature: 240 ° C (heating temperature 240 ° C, preheating time: 7 minutes)
Press pressure: 300 kg / cm ²
Press time: 1 minute After press molding, the mold was cooled to near room temperature with ice water to obtain a sample sheet.

<Measurement>
About 0.4 g of the obtained sample sheet was sealed in the following measurement container, and DSC measurement was performed under the following measurement conditions.

(Measurement container)
Aluminum PAN (DSC PANS 10 μl BO-14-3015)
Aluminum COVER (DSC COVER BO14-3003)
(Measurement condition)
First step: The temperature is raised to 240 ° C. at 30 ° C./min and held for 10 minutes.

    Second step: The temperature is lowered to 30 ° C. at 10 ° C./min.

    Third step: The temperature is raised to 240 ° C. at 10 ° C./min.

(TREF measurement conditions and equipment used)
TREF (temperature rising elution fractionation method) measurement was performed under the following conditions.

  For the propylene homopolymer, the elution temperature-elution amount curve by temperature rising elution fractionation (TREF) was measured as follows, and the peak top temperature and elution integral amount of the maximum peak were determined.

  First, a sample solution in which a sample (propylene homopolymer) was dissolved in o-dichlorobenzene was introduced into a TREF column (column temperature 95 ° C.) containing a filler. Next, the temperature of the column was decreased to 0 ° C. at a temperature decrease rate of 0.5 ° C./min and then held for 10 minutes to crystallize the sample on the surface of the packing material.

  Thereafter, the column temperature was raised to 140 ° C. at a rate of temperature rise of 1.0 ° C./min, and the concentration of the sample (propylene homopolymer) eluted at each temperature was detected. Then, the elution temperature-elution amount curve is measured from the value of the elution amount (mass%) of the sample (propylene homopolymer) and the temperature in the column (° C.) at that time, and the peak top temperature and elution integration amount of the maximum peak are measured. Asked.

(Measurement condition)
Measuring device: Temperature rising elution fractionator TREF200 + type (manufactured by Polymer ChAR)
TREF column: stainless steel microball column (3/8 "od x 150 mm)
Eluent: o-dichlorobenzene (300ppm containing BHT) (= ODCB)
Sample concentration: 0.2% (w / v)
Injection volume: 0.3 mL
Pump flow rate: 0.5 mL / min Detector: Infrared spectrophotometer IR4 (manufactured by Polymer ChAR)
Detection wave number: 3.42 μm
Sample dissolution conditions: 150 ° C. × 90 min dissolution → 95 ° C. × 45 min standing (Gurley air permeability)
It was measured according to JIS P8117. The measuring apparatus used was a B-type Gurley type densometer (manufactured by Toyo Seisakusho). Test temperature 23 ° C., humidity 50% RH. Sample area is 645mm ²
. Due to the cylinder weight of 567 g, the air in the cylinder is passed out of the cylinder through the test hole. The time required for 100 cc of air to pass through was measured and used as the air permeability.

(Puncture strength)
The maximum load when piercing at 2 mm / second using a needle having a diameter of 1 mm and 0.5 mmR was measured and converted to a thickness of 25 mm. The measurement conditions are described below:
Testing machine: Toyo Seiki Seisakusho Strograph V10-D
Test speed: 120 mm / min
Tip: 1.0mmΦ, 0.5mmR
Receiving: 30.0mmΦ (Gloss test jig)
(Heat shrinkage)
The biaxially stretched film was cut into a length of 100 mm and a width of 10 mm in the MD direction. The cut one was placed in a 120 ° C. hot air oven and heated for 15 minutes. The thermal contraction rate (%) was determined by the ratio of the contracted length to the original length.

[Production method of microporous membrane]
A microporous membrane used for measurement of Gurley air permeability and puncture strength was manufactured as follows.

After melt extrusion at 230 ° C. with a T-die having a width of 300 mm and a lip opening of 4 mm, it was taken up at 8 m / min with an 80 ° C. cooling roll. The draft ratio at this time was 86, and the film thickness of the obtained unstretched polypropylene film was 40 μm. After that, 20% low-temperature stretching is performed between nip rolls maintained at 35 ° C., followed by high-temperature stretching with a roll heated to 126 ° C. until the total stretching amount becomes 180%, and then relaxed by 36% with a roll heated to 126 ° C. A microporous membrane was obtained.

[Method for producing biaxially stretched film]
The biaxially stretched film used for the measurement of the heat shrinkage rate was manufactured as follows.

  Using a 30 mmφ extruder (extruded sheet molding machine manufactured by GM Engineering Co., Ltd.), the pellet was melted at a molding temperature of 210 ° C., extruded from a T-die, and cooled by a cooling roll held at a cooling temperature of 30 ° C. The sheet was cooled at a take-up speed of 1.0 m / min to obtain a sheet having a thickness of 0.5 mm.

This sheet is cut into 85 mm × 85 mm, and biaxial stretching machine (KARO manufactured by Bruckner)
IV), a preheating temperature of 152 ° C., a preheating time of 60 seconds, a stretching temperature of 152 ° C., a stretching ratio of 5 × 7 times (MD direction: 5 times, TD direction: 7 times), and a stretching speed of 6 m / min. Sequentially biaxially stretched to obtain a biaxially stretched film having a thickness of 15 μm.

  The evaluation results of Examples and Comparative Examples are shown in Table 1.

Claims (9)

Microporous membrane made of flop propylene polymer satisfying the following requirements (1) to (4);
(1) According to ASTM D1238E standard, the melt flow rate measured at 230 ° C. is 1 to 10 g / 10 min.
(2) Mesopentad fraction measured by ¹³ C-NMR (nuclear magnetic resonance method) is 94.0 to 99.5%.
(3) Melting | fusing point measured with the differential scanning calorimeter (DSC) is 150-167 degreeC.
(4) The peak top temperature measured by TREF is 114 to 125 ° C., and the integrated amount of elution at 110 ° C. is 40 wt% or less. Microporous membrane propylene polymer according to claim 1, consisting flop propylene polymer according to claim 1, characterized by further satisfying the requirements of (5) below.
(5) The room temperature xylene soluble component content (CXS) is less than 4%. The propylene polymer according to claim 1 or 2,
(I) a solid titanium catalyst component containing titanium, magnesium, halogen and a cyclic ester compound (a) specified by the following formula (1);
Group 1 (II) Periodic Table, Group 2, according to claim 1 or 2 is a pulp propylene polymer obtained using an olefin polymerization catalyst comprising an organometallic compound component containing an element belonging to Group 13 A microporous membrane made of a propylene polymer.

(In Formula (1), n is an integer of 5-10.
R ² and R ³ are each independently COOR ¹ or R, and at least one of R ² and R ³ is COOR ¹ . Single bonds in the cyclic skeleton (except for C ^a -C ^a bonds and C ^a -C ^b bonds when R ³ is R) may be replaced by double bonds.
R ¹ is each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms.
A plurality of Rs are each independently an atom or group selected from a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, a nitrogen-containing group, an oxygen-containing group, a phosphorus-containing group, a halogen-containing group and a silicon-containing group. And may be bonded to each other to form a ring, but at least one R is not a hydrogen atom.
A double bond may be contained in the ring skeleton formed by bonding R to each other, and when the ring skeleton contains two or more C ^a bonded with COOR ¹ , The number of carbon atoms constituting the skeleton is 5 to 10. ). A separator comprising a microporous membrane made of the propylene polymer according to claim 1. A filtration membrane comprising a microporous membrane comprising the propylene polymer of claim 1. A separation membrane comprising a microporous membrane comprising the propylene polymer according to claim 1.   The separator according to claim 4, wherein the separator is used for a battery or a capacitor.   The separator according to claim 7, wherein the separator is used for a lithium ion secondary battery.   The separation membrane according to claim 6, which is used for medical use.