JP5685056B2 - Method for producing polyolefin stretch molded article - Google Patents

Description

  The present invention relates to a method for producing a stretched polyolefin article. More specifically, the present invention relates to a method for producing a high-strength polyolefin stretch-molded body having good tensile properties and excellent shape stability.

  Since polyethylene has a relatively low melting point, it has excellent moldability, has high resistance to acidic and alkaline chemicals, and is excellent in moisture resistance. Utilizing these features, polyolefins based on polyethylene molded into non-porous membranes are widely used as moisture-proof packaging materials, etc., and polyolefins based on polyethylene are made porous Polyolefin membranes molded into film and hollow fibers are used for battery separators and filters. On the other hand, ultra-high molecular weight polyethylene, which has a much higher molecular weight than general-purpose polyethylene, is an engineering plastic that has excellent impact resistance, wear resistance, and self-lubricating properties, and is processed into a desired shape. Thus, if it can be highly oriented, a molded product having high strength and high elasticity can be obtained. Therefore, various utilization methods have been studied by kneading with a low molecular weight polyolefin, a plasticizer or the like.

  Patent Document 1 discloses a so-called “gel spinning method” technique in which gel fibers obtained by dissolving ultrahigh molecular weight polyethylene in a solvent are stretched at a high magnification as an application comprising only ultrahigh molecular weight polyethylene. ing. The high-strength polyethylene fibers obtained by the “gel spinning method” are known to have very high strength and elastic modulus as organic fibers, and also have very excellent impact resistance. The knowledge is also applied to polyolefin stretch-molded bodies.

  Patent Documents 2 to 5 describe a method of forming a film by mixing a polyolefin mainly composed of ultrahigh molecular weight polyethylene with a solvent to reduce the viscosity. The film obtained by this method is suitable as a battery separator, and a polyolefin component having a low molecular weight plays a role of a fuse for ensuring the safety of the battery.

  Patent Document 6 describes a polyethylene resin composition comprising components having different intrinsic viscosities. Along with ultra-high molecular weight polyethylene, it is soft and hard, has a molecular weight distribution suitable for coating molding, or a high-flow polyethylene resin composition suitable for injection molding, and is melt-blended and molded. A resin composition having an excellent balance of self-lubricity, appearance, moldability and the like is obtained.

  As these patent documents show, since the ultrahigh molecular weight polyethylene has an extremely high melt viscosity, various devices are required to produce a stretched polyolefin molded article containing the ultrahigh molecular weight polyethylene. However, in the process of kneading components having extremely different molecular weights, the kneaded state tends to be deteriorated due to the difference in melt viscosity, so that undissolved components and dispersion unevenness are generally likely to occur. Further, if the temperature of the kneader and the kneading speed are increased in order to improve the kneading property, the ultra high molecular weight polyethylene is likely to be deteriorated, and the quality of the product may be greatly impaired. Against such a background, ultrahigh molecular weight polyethylene with extremely strong molecular chain entanglement is suppressed while preventing deterioration, and a high-strength polyolefin stretch-molded body is produced by making the most of the characteristics of ultrahigh molecular weight polyethylene. The method has been anxious.

JP-A-56-15408 Japanese Patent Publication No. 5-54495 Japanese Patent No. 4033246 JP 2007-70609 A Japanese Patent Laid-Open No. 11-60791 Japanese Patent No. 4173444

  An object of the present invention is to provide a high-strength polyolefin stretch-molded body having good tensile properties and excellent shape stability.

  As a result of intensive studies to solve the above problems, the present inventor has melt-kneaded a specific ultrahigh molecular weight polyethylene and a plasticizer to form a gel having a melt viscosity of 1 to 240 Pa · s, and then a specific high By supplying molecular weight polyethylene, it has been found that a high-strength polyolefin stretch-molded article having good tensile properties and excellent shape stability can be obtained, and the present invention has been completed. That is, the present invention is as follows.

(1) A method for producing a stretched polyolefin product comprising an ultrahigh molecular weight polyethylene having a viscosity average molecular weight of 1,500,000 to 10,000,000 and a high molecular weight polyethylene having a viscosity average molecular weight of 100,000 to 1,000,000, the ultrahigh molecular weight polyethylene And a plasticizer are melt-kneaded to form a gel having a melt viscosity of 1 to 240 Pa · s, and then the high molecular weight polyethylene is fed to the gel and mixed, and the resulting mixture is stretch-molded to produce a polyolefin stretch-molded body A process for producing a stretched polyolefin molded article, characterized in that
(2) The method for producing a stretched polyolefin molded article according to (1) above, wherein the melt viscosity of a gel formed by melt-kneading ultrahigh molecular weight polyethylene and a plasticizer is 10 to 200 Pa · s.
(3) The ultra-high molecular weight polyethylene has a viscosity average molecular weight of 2 million to 4 million and an average particle size of 10 to 400 μm. The polyolefin stretch-molded article according to the above (1) or (2), Production method.
(4) The polyolefin stretch molded article according to any one of (1) to (3) above, wherein the ultrahigh molecular weight polyethylene is an ultrahigh molecular weight polyethylene polymerized using the following olefin polymerization catalyst: Production method:
An olefin polymerization catalyst comprising a solid catalyst component [A] and an organometallic compound component [B], wherein the solid catalyst component [A] is represented by the following general formula (1)
^{_{M 1 E Mg G R 1 p}} R 2 q X r Y s ····· (1)
(In the above general formula (1), M ¹ is a metal atom included in the group consisting of Group 1, Group 2, Group 3, Group 12 and Group 13 of the periodic table, and R ¹ and R ² are carbon atoms. 2 to 20 hydrocarbon groups, X and Y are the same or different OR ³ , OSiR ⁴ R ⁵ R ⁶ , NR ⁷ R ⁸ , SR ⁹ , a functional group selected from halogen, R ³ and R ⁹ are carbon numbers 1 to 20 hydrocarbon groups, R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ are hydrogen atoms or hydrocarbon groups having 1 to 20 carbon atoms, E, G, p, q, r, and s are , E ≧ 0, G> 0, p ≧ 0, q ≧ 0, r ≧ 0, s ≧ 0, p + q> 0, 0 ≦ (r + s) / (E + G) ≦ 2, kE + 2G = p + q + r + s (k is M ¹ Valence).)
An organomagnesium compound soluble in a hydrocarbon solvent represented by the following general formula (2):
Ti (OR ¹⁰ ) _w Z _4-w (2)
(In the general formula (2), R ¹⁰ is a hydrocarbon group, Z is a halogen, and w is a number satisfying 0 ≦ w ≦ 4.)
In the solid catalyst component [A], the organometallic compound component [B] is represented by the following general formula (3).
AlR ¹¹ _f T _3-f (3)
(In the above general formula (3), R ¹¹ is a hydrocarbon group having 1 to 12 carbon atoms, T is a group selected from hydrogen, halogen, alkoxy, allyloxy and siloxy groups, and f is a number of 2 to 3. is there.)
An olefin polymerization catalyst obtained by mixing an organoaluminum compound represented by the formula:

  The polyolefin stretch-molded product obtained by the present invention is useful as a high-strength polyethylene stretch-molded product having good tensile properties and excellent shape stability.

The flow sheet figure which shows the structure of the catalyst in this invention.

The present invention will be specifically described below.
The method for producing a stretched polyolefin article of the present invention is a method for producing a stretched polyolefin article comprising ultrahigh molecular weight polyethylene having a viscosity average molecular weight of 1,500,000 to 10,000,000 and high molecular weight polyethylene having a viscosity average molecular weight of 100,000 to 1,000,000. The ultra high molecular weight polyethylene and a plasticizer are melt-kneaded to form a gel having a melt viscosity of 1 to 240 Pa · s, and then the high molecular weight polyethylene is supplied to the gel and mixed. To obtain a polyolefin stretch-molded product.

  The ultra high molecular weight polyethylene in the present invention is an ethylene homopolymer having a viscosity average molecular weight of 1,500,000 to 10,000,000, and the viscosity average molecular weight is in the range of 1,600,000 to 7,000,000 in view of the balance between moldability and final physical properties. Is more preferable, and it is more preferably in the range of 1.8 million to 5 million, and particularly preferably 2 million to 4 million. In addition, the viscosity average molecular weight in this invention points out the value which converted the intrinsic viscosity calculated | required from the specific viscosity of the polymer solution into the viscosity average molecular weight.

  The high molecular weight polyethylene in the present invention is an ethylene homopolymer having a viscosity average molecular weight of 100,000 to 1,000,000, and the viscosity average molecular weight may be in the range of 120,000 to 800,000 in view of the balance between moldability and final physical properties. Preferably, it is more preferably in the range of 150,000 to 700,000, and particularly preferably in the range of 200,000 to 500,000. The amount of the high molecular weight polyethylene to be used is not particularly limited, but is preferably 0.01 to 300 parts by weight, more preferably 0.02 to 100 parts by weight with respect to 1 part by weight of the ultra high molecular weight polyethylene. preferable.

  As the ultrahigh molecular weight polyethylene and the high molecular weight polyethylene in the present invention, the resin powder obtained by polymerization may be used as it is, or may be used after classification. The high molecular weight polyethylene may be a product shaped into a shape other than powder, or may be a product obtained by pulverizing them by a known method such as mechanical pulverization, freeze pulverization, chemical pulverization, or the like.

  There is no restriction | limiting in particular about the shape in case the ultra high molecular weight polyethylene in this invention is powder. It may be spherical or indefinite, and may be composed of primary particles, secondary particles in which a plurality of primary particles are aggregated and integrated, or secondary particles that are further pulverized.

  The average particle diameter of the ultra high molecular weight polyethylene in the present invention is a particle diameter with a cumulative weight of 50%, that is, a median diameter, preferably in the range of 10 to 400 μm, more preferably in the range of 20 to 350 μm. A range of 25 to 300 μm is particularly preferable. When the average particle size is larger than 10 μm, handling is easy, and when the average particle size is smaller than 400 μm, it is preferable because undissolved residue and dispersion unevenness hardly occur.

  Although there is no restriction | limiting in particular as a catalyst for superposing | polymerizing ultra high molecular weight polyethylene in this invention, Since the ultra high molecular weight polyethylene excellent in shape stability is obtained when the following olefin polymerization catalyst is used, it is preferable.

An olefin polymerization catalyst comprising a solid catalyst component [A] and an organometallic compound component [B], wherein the solid catalyst component [A] is represented by the following general formula (1)
^{_{M 1 E Mg G R 1 p}} R 2 q X r Y s ····· (1)
(In the above general formula (1), M ¹ is a metal atom included in the group consisting of Group 1, Group 2, Group 3, Group 12 and Group 13 of the periodic table, and R ¹ and R ² are carbon atoms. 2 to 20 hydrocarbon groups, X and Y are the same or different OR ³ , OSiR ⁴ R ⁵ R ⁶ , NR ⁷ R ⁸ , SR ⁹ , a functional group selected from halogen, R ³ and R ⁹ are carbon numbers 1 to 20 hydrocarbon groups, R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ are hydrogen atoms or hydrocarbon groups having 1 to 20 carbon atoms, E, G, p, q, r, and s are , E ≧ 0, G> 0, p ≧ 0, q ≧ 0, r ≧ 0, s ≧ 0, p + q> 0, 0 ≦ (r + s) / (E + G) ≦ 2, kE + 2G = p + q + r + s (k is M ¹ Valence).)
An organomagnesium compound soluble in a hydrocarbon solvent represented by the following general formula (2):
Ti (OR ¹⁰ ) _w Z _4-w (2)
(In the general formula (2), R ¹⁰ is a hydrocarbon group, Z is a halogen, and w is a number satisfying 0 ≦ w ≦ 4.)
In the solid catalyst component [A], the organometallic compound component [B] is represented by the following general formula (3).
AlR ¹¹ _f T _3-f (3)
(In the above general formula (3), R ¹¹ is a hydrocarbon group having 1 to 12 carbon atoms, T is a group selected from hydrogen, halogen, alkoxy, allyloxy and siloxy groups, and f is a number of 2 to 3. is there.)
An olefin polymerization catalyst obtained by mixing an organoaluminum compound represented by the formula:

  In addition, the nomenclature established in 1989 by the IUPAC (International Pure and Applied Chemistry) inorganic chemical nomenclature was used for the group number of the periodic table.

  It is important that the hydrocarbon solvent in the present invention is inert, aliphatic hydrocarbons such as pentane, hexane and heptane, aromatic hydrocarbons such as benzene and toluene, or alicyclic such as cyclohexane and methylcyclohexane. A hydrocarbon etc. are mentioned.

As the organomagnesium compound soluble in the hydrocarbon solvent used in the present invention, an organomagnesium compound represented by the following general formula (1) is used.
^{_{M 1 E Mg G R 1 p}} R 2 q X r Y s ····· (1)
(In the above general formula (1), M ¹ is a metal atom included in the group consisting of Group 1, Group 2, Group 3, Group 12 and Group 13 of the periodic table, and R ¹ and R ² are carbon atoms. 2 to 20 hydrocarbon groups, X and Y are the same or different OR ³ , OSiR ⁴ R ⁵ R ⁶ , NR ⁷ R ⁸ , SR ⁹ , a functional group selected from halogen, R ³ and R ⁹ are carbon numbers 1 to 20 hydrocarbon groups, R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ are hydrogen atoms or hydrocarbon groups having 1 to 20 carbon atoms, E, G, p, q, r, and s are , E ≧ 0, G> 0, p ≧ 0, q ≧ 0, r ≧ 0, s ≧ 0, p + q> 0, 0 ≦ (r + s) / (E + G) ≦ 2, kE + 2G = p + q + r + s (k is M ¹ Valence).)

  This compound is shown as a complex form of organomagnesium soluble in a hydrocarbon solvent, but encompasses all dihydrocarbylmagnesium compounds and complexes of this compound with other metal compounds. The relational expression kE + 2G = p + q + r + s of the symbols E, G, p, q, r, and s indicates the stoichiometry between the valence of the metal atom and the substituent. The range of the molar composition ratio (r + s) / (E + G) of X and Y with respect to all metal atoms is 0 ≦ (r + s) / (E + G) ≦ 2, and particularly preferably 0 ≦ (r + s) / (E + G) ≦ 1.

The hydrocarbon group represented by R ¹ , R ² , R ³ , and R ⁹ in the above formula is preferably an alkyl group, a cycloalkyl group, or an aryl group, for example, a methyl group (R ³ and R ⁹ ), Ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, cyclohexyl group, phenyl group and the like, and R ¹ is more preferably an alkyl group. Further, when R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ are hydrocarbon groups, they are preferably alkyl groups, cycloalkyl groups, or aryl groups, such as methyl groups, ethyl groups, propyl Group, butyl group, pentyl group, hexyl group, octyl group, decyl group, cyclohexyl group, phenyl group and the like, and an alkyl group or an aryl group is more preferable.

In the case of E> 0, as the metal atom M ¹ , a metal element included in the group consisting of Group 1, Group 2, Group 3, Group 12, and Group 13 of the Periodic Table can be used. Examples thereof include lithium, sodium, potassium, beryllium, zinc, boron, and aluminum, and aluminum, boron, beryllium, and zinc are particularly preferable. Metal atom ^M ratio G / E of magnesium to ¹ can be arbitrarily set, preferably in the range of 0.1 to 30, especially 0.5 to 10 is preferred.

In the present invention, these organomagnesium compounds include those represented by the general formulas R ¹ MgZ and R ¹ ₂ Mg (wherein R ¹ has the above-mentioned meaning and Z is a halogen). An organometallic compound belonging to the group consisting of M ¹ R ² _k and M ¹ R ² _k-1 H (wherein M ¹ , R ² and k are as defined above) in an inert hydrocarbon solvent, It is synthesized by reacting between room temperature and 150 ° C. and, if necessary, subsequently reacting it with additional components such as alcohol, water, siloxane, amine, imine, mercaptan, or dithio compounds. Regarding the order of the reaction, any of a method of adding an additional component to the organic magnesium compound, a method of adding the organic magnesium compound to the additional component, or a method of adding both at the same time can be used.

Further, these organomagnesium compounds include organomagnesium compounds belonging to the group consisting of general formulas MgX ₂ and R ¹ MgX, and organometallics belonging to the group consisting of general formulas M ¹ R ² _k and M ¹ R ² _k-1 H. Reaction with a compound, or a reaction between an organomagnesium compound belonging to the group consisting of the general formulas R ¹ MgX and R ¹ ₂ Mg and an organometallic compound belonging to the group consisting of the general formula R ² _t M ¹ X _k-t , or An organic magnesium compound belonging to the group consisting of R ¹ MgX and R ¹ ₂ Mg and a general formula Y _t M ¹ X _kt (wherein M, R ¹ , R ² , X and Y are as defined above) In which X and Y are halogens, and t is a number from 0 to k.) Can also be synthesized by reaction with an organometallic compound belonging to the group consisting of:

In the present invention, the organomagnesium compound represented by the general formula (1) is an organomagnesium compound in which r = s = 0 in the general formula (1), s = 0 in the general formula (1), and X = OR ³ It is particularly preferable to use a reaction product of an organomagnesium compound or an organomagnesium compound in which r = s = 0 in the general formula (1) and a linear or cyclic siloxane compound represented by the following general formula (4).

(In the general formula ^{(4), R 12, R} 13 is hydrogen or a hydrocarbon group having 1 to 10 carbon atoms, e is an integer from 2 to 40.)

The hydrocarbon group represented by R ³ of the organomagnesium compound in which s = 0 and X = OR ³ in the general formula (1) is preferably an alkyl group or aryl group having 1 to 12 carbon atoms, particularly 3 to 3. Ten alkyl groups or aryl groups are preferred. Specifically, for example, methyl group, ethyl group, propyl group, 1-methylethyl group, butyl group, 1-methylpropyl group, 1,1-dimethylethyl group, pentyl group, hexyl group, 2-methylpentyl group 2-ethylbutyl group, 2-ethylpentyl group, 2-ethylhexyl group, 2-ethyl-4-methylpentyl group, 2-propylheptyl group, 2-ethyl-5-methyloctyl group, octyl group, nonyl group, decyl Group, phenyl group, naphthyl group and the like, and butyl group, 1-methylpropyl group, 2-methylpentyl group and 2-ethylhexyl group are particularly preferable.

The hydrocarbon group represented by R ¹² and R ¹³ in the general formula (4) is an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group, such as a methyl group, an ethyl group, or a propyl group. Group, isopropyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, cyclohexyl group, phenyl group, 2-methylphenyl group, 4-methylphenyl group, 2,4-dimethylphenyl group and the like. An alkyl group having 1 to 3 carbon atoms such as a methyl group, an ethyl group, a propyl group, and an isopropyl group and an aromatic hydrocarbon group having 7 or less carbon atoms are preferable, and a methyl group and a phenyl group are particularly preferable. The siloxane compound is preferably polyhydromethylsiloxane or polyhydrophenylsiloxane. Moreover, although e is an integer of 2-40, 4-20 are preferable and 7-15 are especially preferable.

  The reaction between the organomagnesium compound in which r = s = 0 in the general formula (1) and the chain or cyclic siloxane compound represented by the general formula (4) may be performed in an inert hydrocarbon solvent. preferable. The reaction temperature is preferably 10 ° C to 150 ° C, particularly preferably 40 ° C to 90 ° C. Although there is no restriction | limiting in particular about reaction time, It is preferable that it is 3 hours or more. The amount of the chain-like or cyclic siloxane compound represented by the general formula (4) is 0.00 by mole ratio relative to all metal atoms in the organomagnesium compound in which r = s = 0 in the general formula (1). A range of 3 to 5 is preferable, and a range of 0.5 to 2 is particularly preferable.

In the present invention, the organomagnesium compound represented by the general formula (1) is inactive in an inert hydrocarbon solvent, and the organomagnesium compound in which E> 0 is soluble. Further, when an organomagnesium compound in which E = 0 is used, for example, when R ¹ is 1-methylpropyl or the like, it is soluble in a hydrocarbon solvent, and such a compound also gives preferable results to the present invention.

In the general formula (1), when E = 0, R ¹ and R ² are recommended to be any one of the following three groups (i), (ii), and (iii).
(I) At least one of R ¹ and R ² is a secondary or tertiary alkyl group having 4 to 6 carbon atoms, preferably both R ¹ and R ² have 4 to 6 carbon atoms, At least one is a secondary or tertiary alkyl group.
(Ii) R ¹ and R ² are alkyl groups having different carbon atoms, preferably R ¹ is an alkyl group having 2 or 3 carbon atoms, and R ² is an alkyl having 4 or more carbon atoms. Be a group.
(Iii) At least one of R ¹ and R ² is a hydrocarbon group having 6 or more carbon atoms, preferably an alkyl group that becomes 12 or more when the number of carbon atoms contained in R ¹ and R ² is added. .

Hereinafter, these groups are specifically shown.
As the secondary or tertiary alkyl group having 4 to 6 carbon atoms in (i), 1-methylpropyl group, 2-methylpropyl group, 1,1-dimethylethyl group, 2-methylbutyl group, 2- Ethylpropyl group, 2,2-dimethylpropyl group, 2-methylpentyl group, 2-ethylbutyl group, 2,2-dimethylbutyl group, 2-methyl-2-ethylpropyl group, etc. are used, and 1-methylpropyl group Is particularly preferred.

  Next, examples of the alkyl group having 2 or 3 carbon atoms in (ii) include an ethyl group, a 1-methylethyl group, a propyl group, and the like, and an ethyl group is particularly preferable. Examples of the alkyl group having 4 or more carbon atoms include a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, and the like, and a butyl group and a hexyl group are particularly preferable.

  Furthermore, in (iii), examples of the alkyl group having 6 or more carbon atoms include hexyl group, heptyl group, octyl group, nonyl group, decyl group, phenyl group, 2-naphthyl group, and the like. An alkyl group is preferable, and a hexyl group and an octyl group are particularly preferable among the alkyl groups.

  Generally, an increase in the number of carbon atoms contained in an alkyl group facilitates dissolution in a hydrocarbon solvent. However, since the viscosity of the solution increases, it is preferable to use an alkyl group having a small number of carbon atoms within a range that satisfies the solubility. The organomagnesium compound is used as a hydrocarbon solution, but it may be used even if a slight amount of a complexing agent such as ether, ester or amine is contained or remains in the solution. The organomagnesium compound soluble in the hydrocarbon solvent used in the present invention plays an extremely important role in amplifying the catalytic function of the solid catalyst component [A] to an industrial level.

As the titanium compound used in the present invention, a titanium compound represented by the following general formula (2) is used.
Ti (OR ¹⁰ ) _w Z _4-w (2)
(In the general formula (2), R ¹⁰ is a hydrocarbon group, Z is a halogen, and w is a number satisfying 0 ≦ w ≦ 4.)

Examples of the hydrocarbon group represented by R ¹⁰ include aliphatic groups such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, 2-ethylhexyl group, heptyl group, octyl group, decyl group, and allyl group. Examples include hydrocarbon groups, cyclohexyl groups, 2-methylcyclohexyl groups, cyclopentyl groups and other alicyclic hydrocarbon groups, and phenyl groups, naphthyl groups and other aromatic hydrocarbon groups, with aliphatic hydrocarbon groups being particularly preferred. . Examples of the halogen represented by Z include chlorine, bromine and iodine, with chlorine being particularly preferred. It is also possible to use a mixture of two or more titanium compounds selected from the above.

  In the present invention, the total amount of the titanium compound represented by the general formula (2) is in the range of 0.05 to 20 mol with respect to 1 mol of the magnesium atom contained in the organomagnesium compound represented by the general formula (1). Is preferable, the range of 0.2 to 10 mol is more preferable, and the range of 0.5 to 5 mol is particularly preferable. The reaction between the organomagnesium compound represented by the general formula (1) and the titanium compound represented by the general formula (2) is performed in an inert hydrocarbon solvent, but an aliphatic hydrocarbon solvent such as hexane or heptane should be used. Is preferred.

  In the present invention, a method of adding an organic magnesium compound soluble in a hydrocarbon solvent and a titanium compound includes a method of adding a titanium compound following an organic magnesium compound soluble in a hydrocarbon solvent, and a hydrocarbon solvent subsequent to the titanium compound. Either a method of adding a soluble organic magnesium compound or a method of adding both at the same time is possible, but a method of adding both an organic magnesium compound soluble in a hydrocarbon solvent and a titanium compound simultaneously is possible. From the viewpoint of the uniformity and handleability of the precipitated solid particles. Although there is no restriction | limiting in particular about the temperature made to contact, It is preferable to carry out in the range of -80 degreeC-150 degreeC, and it is especially preferable to carry out in the range of -40 degreeC-100 degreeC.

  The solid catalyst component [A] in the present invention is obtained by reacting an organomagnesium compound soluble in a hydrocarbon solvent represented by the general formula (1) with a titanium compound represented by the general formula (2), and then reacting mechanically. Shear stress may be applied. Here, the mechanical shear stress in the present invention is a shear stress generated by applying a frictional load having impact and cavitation. The mechanical shear stress in the present invention is applied after the solid particle precipitation reaction is completed.

  In the present invention, the mechanical shear stress applied after reacting the organomagnesium compound soluble in the hydrocarbon solvent and the titanium compound is preferably applied in a slurry state in which solid particles are dispersed in the inert hydrocarbon solvent. It is particularly preferable to use an aliphatic hydrocarbon solvent such as hexane or heptane. The slurry concentration is preferably in the range of 1 to 150 grams / liter, and particularly preferably in the range of 5 to 100 grams / liter.

In general, when a mechanical shear stress is applied in a slurry state in which solid particles are dispersed in a liquid, the particles are pulverized and finely divided, a uniform particle size distribution is obtained, or the dispersibility of the particles is improved. Although the effect of adjusting the shape can be obtained, the present invention is characterized by increasing the particle shape of the solid catalyst component [A] by applying mechanical shear stress. When ethylene is polymerized by the gas method or the slurry method, the shape of the solid catalyst component [A] is directly reflected in the shape of the ultrahigh molecular weight polyethylene powder. By polymerization, an ultrahigh molecular weight polyethylene powder having excellent moldability can be obtained.

  In the present invention, the solid particles obtained by reacting the organomagnesium compound soluble in the hydrocarbon solvent represented by the general formula (1) and the titanium compound represented by the general formula (2) have an average particle size of 0.00. The range of 5-20 micrometers is preferable, More preferably, it exists in the range of 1-20 micrometers, and it has the characteristics which are easy to aggregate especially in an inert hydrocarbon solvent. On the other hand, the solid particles have a feature that they are easily subjected to a shape change caused by external energy. That is, as a phenomenon resulting from both of these characteristics, when a mechanical shear stress is applied to the solid particles, shape change and aggregation are repeated, and very bulky particles are formed. When the average particle size of the solid particles is not within the above range, the formation of bulky particles due to mechanical shear stress may not sufficiently proceed. Here, the average particle diameter in the present invention is the particle diameter at which the cumulative weight is 50%, that is, the median diameter.

  In the present invention, the device for mechanically applying shear stress is preferably a pulverizer. Examples of the pulverizer include ball mills, bead mills, tube mills, rod mills, vibration mills, and wet / pulverized pulverizers such as rotor / stator type homogenizers. This is preferable because bulky particles can be obtained while suppressing excessive miniaturization.

  The ball mill in the present invention is an apparatus for grinding raw material powder by putting a hard ball and raw material powder in a cylindrical can body and rotating the same. Hard balls include ceramic balls such as zirconia, alumina, natural silica, and glass, metal balls such as steel and stainless steel, iron cored nylon spheres, iron cored Teflon (registered trademark) balls and other metal coated balls, nylon, Examples thereof include resin balls such as Teflon (registered trademark) and polypropylene.

  The rotor / stator type homogenizer in the present invention is a dispersion device that utilizes centrifugal force composed of two tooth-shaped rings. The outer fixed tooth profile ring is called a stator (fixed blade), and the tooth ring rotating inside the stator is called a rotor (rotary blade), which is driven by a motor through a shaft. The raw material powder is ground by shearing stress generated between the rotating rotor and the stator.

  The bead mill in the present invention is a device that fills a bead (medium) into a vessel (container) having a rotation shaft in the center and gives a movement caused by the rotation of the rotation shaft. is there.

  The tube mill in the present invention is a continuous ball mill that supplies raw material powder from one end of a tube-shaped can body and takes it out from the other end.

  The rod mill in the present invention is an apparatus for grinding raw material powder by putting a rod-like rod and raw material powder slightly shorter than the length of the inner surface of the cylindrical can body into a cylindrical can body and rotating it. Although the structure is almost the same as that of the ball mill, the balls are in contact with each other at a point, whereas the rods are in contact with each other with a line, so that it has a feature of preferentially grinding coarse particles over the ball mill.

  The vibration mill in the present invention is an apparatus that grinds raw material powder by causing high-speed circular vibration of a pulverizing cylinder into which raw material powder is inserted.

  In the present invention, the temperature at which the shear stress is mechanically applied is preferably in the range of −50 to 100 ° C., particularly preferably in the range of −20 to 70 ° C., at which the catalytic activity of the solid catalyst component [A] does not deteriorate. In addition, the time for mechanically applying the shear stress in the present invention is not particularly limited as long as the desired solid catalyst component [A] can be obtained, but the formation of bulky particles sufficiently proceeds, and further polymerization is performed. From the viewpoint of obtaining a desirable powder from an industrial point of view, such as fluidity of the ultra-high molecular weight polyethylene powder obtained by packaging and packaging during transportation, a range of 5 minutes to 100 hours is preferable, and a range of 10 minutes to 30 hours is preferable. Particularly preferred.

  The solid catalyst component [A] thus obtained is used as a slurry solution using an inert hydrocarbon solvent. The solid catalyst component [A] of the present invention is combined with the organometallic compound component [B] to become a more highly active polymerization catalyst.

As the organometallic compound component [B] in the present invention, an organoaluminum compound represented by the following general formula (3) is used.
AlR ¹¹ _f T _3-f (3)
(In the above general formula (3), R ¹¹ is a hydrocarbon group having 1 to 12 carbon atoms, T is a group selected from hydrogen, halogen, alkoxy, allyloxy and siloxy groups, and f is a number of 2 to 3. is there.)

  In addition, said organoaluminum compound may be used independently and may be used as a mixture consisting of a plurality of organoaluminum compounds.

The hydrocarbon group having 1 to 20 carbon atoms represented by R ¹¹ in the above formula includes aliphatic hydrocarbons, aromatic hydrocarbons, and alicyclic hydrocarbons. Specific examples of the organoaluminum compound represented by the general formula (3) include trimethylaluminum, triethylaluminum, tripropylaluminum, tributylaluminum, triisobutylaluminum, tripentylaluminum, tris (3-methylbutyl) aluminum, and trihexylaluminum. Trialkylaluminum such as trioctylaluminum and tridecylaluminum, aluminum hydride compounds such as diethylaluminum hydride and diisobutylaluminum hydride, diethylaluminum chloride, ethylaluminum dichloride, diisobutylaluminum chloride, ethylaluminum sesquichloride, diethylaluminum bromide and the like Aluminum halide compound, diethyla Preferred are alkoxyaluminum compounds such as minium ethoxide and diisobutylaluminum butoxide, siloxyaluminum compounds such as dimethylhydrosiloxyaluminum dimethyl, ethylmethylhydrosiloxyaluminum diethyl and ethyldimethylsiloxyaluminum diethyl, and mixtures thereof, trialkylaluminum compounds, hydrogenated Aluminum compounds and mixtures thereof are particularly preferred.

  The mixing of the solid catalyst component [A] and the organometallic compound component [B] includes both the case where the solid catalyst component [A] is added to the polymerization system under the polymerization conditions and the case where the solid catalyst component [A] is combined prior to the polymerization. The ratio of the two components to be combined is preferably in the range of 1 to 3000 mmol of the organometallic compound [B] with respect to 1 g of the solid catalyst component [A].

  Although there is no restriction | limiting in particular about the manufacturing method of ultra high molecular weight polyethylene and high molecular weight polyethylene in this invention, When obtaining superposition | polymerization powder directly, a gas method or a slurry method is preferable and the slurry method which is excellent in heat removal efficiency is especially preferable. There is no restriction | limiting in particular about the polymerization pressure in this invention, Usually, it is 0.1 MPa-5 MPa as a gauge pressure, However, 0.1 MPa-1 MPa are preferable in the case of slurry polymerization. There is no restriction | limiting in particular about the polymerization temperature in this invention, Usually, it is 25 to 300 degreeC, However, In the case of slurry polymerization, 25 to 120 degreeC is preferable and 50 to 100 degreeC is especially preferable.

  As the solvent for slurry polymerization in the present invention, a commonly used inert hydrocarbon solvent is used, for example, an aliphatic hydrocarbon such as isobutane, pentane, hexane, and heptane, an aromatic hydrocarbon such as benzene and toluene, or And alicyclic hydrocarbons such as cyclohexane and methylcyclohexane.

  The molecular weight of the polymer obtained by the present invention can be adjusted by changing the concentration of hydrogen present in the polymerization system, changing the polymerization temperature, or changing the concentration of the organometallic compound [B]. . Further, by connecting two or more reactors in series and / or in parallel, the molecular weight distribution, the side chain distribution, and the like can be controlled.

  In the present invention, the polyolefin stretch-molded product is obtained by melt-kneading the ultrahigh molecular weight polyethylene defined in the present invention with a plasticizer to form a gel having a predetermined melt viscosity, and then supplying the predetermined high molecular weight polyethylene to the gel. The resulting mixture is stretch-molded, and the shape of the molded body is not particularly limited. For example, you may shape | mold in any shapes, such as a fiber, a film, a sheet | seat, a tape, or a porous membrane.

  The ultrahigh molecular weight polyethylene defined in the present invention and polyolefins other than the high molecular weight polyethylene can be used in combination as long as the requirements of the present invention are not impaired. Examples of such polyolefins include ethylene homopolymers having a viscosity average molecular weight of less than 100,000, propylene homopolymers, ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene and Examples include copolymers such as 1-octene, or cyclic olefin copolymers such as ethylene / methylpentene copolymer, ethylene / tetracyclododecene copolymer, and ethylene / norbornene copolymer. One or more of each or both can be used in an amount of 0.001 to 10 parts by weight with respect to 1 part by weight of the ultrahigh molecular weight polyethylene. Furthermore, if necessary, known additives such as metal soaps such as calcium stearate and zinc stearate, ultraviolet absorbers, light stabilizers, antistatic agents, antifogging agents, and coloring pigments also impair the moldability. In addition, 0.001 to 10 parts by weight can be used with respect to 1 part by weight of the ultrahigh molecular weight polyethylene by mixing within a range that does not impair the requirements and effects of the present invention. In the present invention, if necessary, 0.001 to 10 parts by weight of inorganic particles represented by silica, alumina, titania and the like can be added to 1 part by weight of the ultrahigh molecular weight polyethylene. The inorganic particles may be extracted in whole or in part in any of the molding steps or may remain in the product. An organic filler can also be added in the range which does not impair the performance of the film.

  The plasticizer in the present invention may be any non-volatile substance that can form a uniform gel above the melting point of the ultra high molecular weight polyethylene when mixed with the ultra high molecular weight polyethylene. For example, liquid paraffin, paraffin wax, decalin (decahydronaphthalene), xylene, n-decane, n-dodecane, 190 ° C., melt flow rate at 2.16 kg load (JIS K7210 (Code D): 1999) is 20 g / 10. Examples include hydrocarbons such as polyolefins for more than 5 minutes, esters such as dioctyl phthalate and dibutyl phthalate, higher alcohols such as oleyl alcohol, stearyl alcohol, decyl alcohol, and nonyl alcohol, and diphenyl ether. In particular, hydrocarbons such as liquid paraffin and decalin (decahydronaphthalene) which are highly compatible with polyethylene are preferable.

  The melting point of the ultra high molecular weight polyethylene in the present invention is a value measured using a differential scanning calorimeter Pyris1 (trade name) manufactured by PERKIN ELMER based on JIS K7121: 1987. After holding 8.4 mg of the sample at 50 ° C. for 1 minute, the temperature is raised to 200 ° C. at a rate of 10 ° C./minute, and the temperature can be determined from the temperature showing the maximum peak in the melting curve obtained at that time.

  In the present invention, the ultrahigh molecular weight polyethylene and a plasticizer are melt-kneaded to form a gel having a melt viscosity of 1 to 240 Pa · s, and then the high molecular weight polyethylene is supplied to the gel and mixed. To obtain a polyolefin stretch-molded product.

  The melt viscosity in the present invention is based on JIS K7199: 1999, using a capillograph (Type 1D) manufactured by Toyo Seiki Seisakusho, using a capillary with a diameter of 1 mm, a length of 9.99 mm, and an inflow angle of 90 °. Apparent viscosity measured in degrees Celsius. The melt viscosity when melt-kneaded ultra high molecular weight polyethylene and a plasticizer into a gel is in the range of 1 to 240 Pa · s, and it is uniform without undissolved components and dispersion unevenness while avoiding deterioration of ultra high molecular weight polyethylene A gel in a simple state can be obtained. The melt viscosity is not particularly limited as long as it is in the range of 1 to 240 Pa · s, but in the case of producing a porous film whose physical property balance greatly affects the performance, it is in the range of 10 to 200 Pa · s. Is preferred.

  The melt kneading method in the present invention is not particularly limited, and any method may be used, such as a kneader, a twin screw extruder, or a mixer type resin kneading equipment, as long as the ultra high molecular weight polyethylene and the plasticizer can be melt kneaded while heating. May be. It is preferable to add an antioxidant in order to prevent oxidation of the ultrahigh molecular weight polyethylene during melt kneading.

  The method for supplying high molecular weight polyethylene in the present invention is not particularly limited, and examples thereof include addition using a piston, pump, screw type feeder, belt type feeder, single screw extruder or twin screw extruder. Among these, it is preferable to use a single screw extruder or a twin screw extruder from the viewpoint of quality.

  In the present invention, the amount of the plasticizer to be melt-kneaded with the ultrahigh molecular weight polyethylene is not particularly limited, but when the plasticizer is extracted after molding, it is 4 to 99 parts by weight with respect to 1 part by weight of the ultrahigh molecular weight polyethylene. Is preferred. In the case of producing a porous membrane or the like whose physical property balance greatly affects the performance, from the viewpoint of the porosity of the obtained membrane, it should be 5 to 40 parts by weight with respect to 1 part by weight of ultrahigh molecular weight polyethylene. preferable. In addition, after melt-kneading the ultrahigh molecular weight polyethylene and the plasticizer, the plasticizer may be further added alone, or the plasticizer may be added by mixing with the subsequently supplied high molecular weight polyethylene.

  In the present invention, the extraction solvent for extracting the plasticizer is preferably a poor solvent for polyethylene, a good solvent for the plasticizer, and a boiling point lower than the melting point of polyethylene. Examples of such extraction solvents include low-boiling hydrocarbons such as n-hexane and cyclohexane, halogenated hydrocarbons such as methylene chloride, 1,1,1-trichloroethane, hydrofluoroether and hydrofluorocarbon, ethanol and the like. Examples include alcohols such as isopropanol and ketones such as acetone and 2-butanone. It selects from these and is used individually or in mixture.

  There is no particular limitation on the stretch molding method in the present invention, and it may be molded by performing sequential biaxial stretching by a roll stretching method or simultaneous biaxial stretching by a tenter method, or a die having an orifice installed is attached to the tip. The melt-kneaded product extruded using an extruder may be taken out, or may be formed by stretching immediately after the melt-kneaded product is extruded from the orifice, or after the melt-kneaded product is cooled. You may shape | mold by extending | stretching at the temperature which does not remelt. Alternatively, the melt-kneaded product extruded using an extruder with a film forming die attached to the tip may be molded by pulling it with a cooling roll, or the melt-kneaded product may be quickly cooled by being sandwiched between cooled metal plates. The molten kneaded product may be cast on a support and then gelled in a water bath, an air bath, or a solvent at a temperature not higher than the gelling temperature, preferably 15 to 25 ° C. at a rate of at least 50 ° C./min. The film may be stretched after cooling. In addition, you may shape | mold continuously and may shape | mold in multiple steps.

  The stretching temperature in the present invention is from room temperature to around the melting point of the polyolefin, preferably 80 to 150 ° C, more preferably 100 to 140 ° C. Moreover, although there is no restriction | limiting in particular about a draw ratio, when manufacturing the porous membrane etc. whose physical property balance influences performance largely, from a viewpoint of ensuring sufficient intensity | strength as a product, 4-400 times are preferable at an area magnification. 10 to 200 times is more preferable, and 30 to 100 times is particularly preferable in order to obtain smoothness in the film width direction. If the stretching ratio is 4 times or more, the strength as a porous film is sufficient, and if it is 400 times or less, not only is stretching easy, but also the porosity of the obtained porous film can be prevented.

  The polyolefin stretch-molded product in the present invention may be porous or nonporous. Further, the porous polyolefin stretch-molded product may be rendered nonporous by a process such as super-stretching.

  Polyolefin stretch-molded articles obtained by the production method of the present invention are used for protective applications such as high-strength fibers and high-strength tapes or special materials, filtration applications such as water treatment devices, storage batteries, capacitors, lithium ion secondary batteries and fuel cells. It can utilize suitably for separator uses, such as.

  Next, although an example and a comparative example explain the present invention, the present invention is not limited to these examples.

  The present invention will be described based on examples.

[Measurement of viscosity average molecular weight]
The viscosity average molecular weight of the ultrahigh molecular weight polyethylene in the examples and comparative examples of the present invention was determined by the method shown below. First, 20 mg of decalin (decahydronaphthalene) was charged with 10 mg of polymer and stirred at 150 ° C. for 2 hours to dissolve the polymer. The drop time (t _s ) between the marked lines was measured using a Ubbelohde type viscometer for the solution in a thermostatic bath at 135 ° C. Similarly, the measurement was performed for a polymer of 5 mg. The falling time (t _b ) of only decalin without a polymer as a blank was measured. The specific viscosity (η _sp / C) of the polymer determined according to the following equation is plotted to derive a linear expression of the concentration (C) and the specific viscosity of the polymer (η _sp / C), and the intrinsic viscosity extrapolated to a concentration of 0 (Η) was determined.
_{η sp / C = (t s} / t b -1) /0.1
From this intrinsic viscosity (η), the viscosity average molecular weight (Mv) was determined according to the following formula.
Mv = 5.34 × 10 ⁴ η ^1.49

[Measurement of melt viscosity]
The solution viscosity in the examples and comparative examples of the present invention is 1 mm in diameter, 9.99 mm in length, and an inflow angle of 90 °, using a capillograph (type 1D) manufactured by Toyo Seiki Seisakusho, based on JIS K7199: 1999. Using a capillary, a barrel with a diameter of 9.55 mm was set at 190 ° C., 7 g of a gel sample was added, and measurement was performed under conditions of a preheating time of 5 minutes, a measurement time of 10 seconds, and an extrusion speed of 50 mm / min. The measurement results of the apparent viscosity eta _a calculated by the following equation.
η _a = τ _a / γ _a (Pa · s)
τ _a = Pr / 2L (Pa)
γ _a = 4Q / πr ³ (second ⁻¹ )
Q = V / 60 (m ³ / sec)
P = F / πR ² (Pa)
V = πR ² v (m ³ / min)
η _a : Apparent viscosity (Pa · s)
τ _a : Apparent Shear stress (Pa)
γ _a : Apparent Shear rate (sec ⁻¹ )
P: Barrel pressure (Pa)
F: Extrusion load (N)
R: Barrel radius (m)
γ: Capillary radius (m)
L: Capillary length (m)
Q: Flow rate (m ³ / sec)
V: Extrusion amount (m ³ / min)
v: Extrusion speed (m / min)
t: Measurement time (seconds)

[Example 1]
(1) Preparation of solid catalyst component [A] An organic magnesium compound represented by the composition formula AlMg ₆ (C ₄ H ₉ ) ₁₂ (C ₂ H ₅ ) ₃ was placed in a 200 ml stainless steel autoclave sufficiently substituted with nitrogen. Charge 40 ml of hexane solution (corresponding to 37.8 mmol as the total amount of aluminum and magnesium) and stir at 25 ° C. 40 ml of hexane containing 2.27 g (37.8 mmol) of methylhydropolysiloxane over 30 minutes And dripped. After dropping, the mixture was heated to 80 ° C. and reacted with stirring for 3 hours to obtain an organomagnesium compound to be brought into contact with the titanium compound.
A 200 ml glass round-bottom flask thoroughly purged with nitrogen was charged with 40 ml of hexane, and while stirring at -10 ° C., 40 ml of a hexane solution of the above organic magnesium compound (equivalent to 16 mmol of magnesium) and 0.4 mol / Liter of titanium tetrachloride hexane solution (50 ml) was added dropwise simultaneously over 2 hours. After dropping, the mixture was further stirred for 1 hour. At this time, the temperature was gradually raised to finally reach 10 ° C. Thereafter, the supernatant liquid was removed, and washing with 70 ml of hexane was performed four times to obtain a solid catalyst component [A]. The average particle diameter of the obtained solid catalyst component [A] was 3.6 micrometers.
(2) Polymerization of ultra high molecular weight polyethylene 0.4 mmol of triisobutylaluminum as the organometallic compound component [B] and 10 mg of the above solid catalyst component [A], together with 0.8 liter of dehydrated and deoxygenated hexane, Was put in an autoclave with an internal volume of 1.5 liters which was degassed by vacuum and purged with nitrogen. Polymerization was started by keeping the internal temperature of the autoclave at 70 ° C. and adding ethylene to bring the total pressure to 0.2 MPa. Polymerization was carried out for 30 minutes while maintaining the total pressure at 0.2 MPa by supplying ethylene. After the polymerization, the polymer was collected by filtration, and washed with methanol and dried to obtain ultrahigh molecular weight polyethylene powder. The ultrahigh molecular weight polyethylene powder obtained by this polymerization had a viscosity average molecular weight of 3,280,000.
(3) Molding of Polyolefin Stretch Molded Body 2.6 g of the above ultra high molecular weight polyethylene powder, 26.5 g of liquid paraffin, and tetrakis [methylene (3,5-di-t-) manufactured by Great Lakes Chemical Japan Co., Ltd. Butyl-4-hydroxy-hydrocinnamate)] 0.4 g of methane (product name: ANOX20) was added to a 200 ml polycup and mixed well, and then Labo plast mill mixer manufactured by Toyo Seiki Seisakusho (main body model: 30C150, mixer) Type: R-60), the number of revolutions was set to 50 rpm, and the mixture was melt-kneaded for 14 minutes while raising the temperature from 120 ° C. to 5 ° C./min to form a gel. Subsequently, 10.6 g of high molecular weight polyethylene powder having a viscosity average molecular weight of 300,000 was supplied by a piston for addition, and kneaded at 190 ° C. for 11 minutes. After the melt-kneaded product was taken out and cooled to room temperature, 14 g of the gel thus obtained was charged into Capillograph 1D (orifice diameter 2 mm) manufactured by Toyo Seiki Seisakusho Co., Ltd., set temperature 180 ° C., extrusion speed 2 mm / min, take-off speed 2 m / It was formed into a thread shape in minutes and was washed with hexane to obtain a polyethylene fiber. As a result of testing the tensile properties based on JIS L1013: 1999, the tensile modulus was good. In addition, when the gel just before supplying the said high molecular weight polyethylene powder was produced separately and melt viscosity was measured, it was 162 Pa.s.

[Comparative Example 1]
Implementation was performed except that the high molecular weight polyethylene powder having a viscosity average molecular weight of 300,000 was supplied from the beginning without being supplied later and melt-kneaded with the ultrahigh molecular weight polyethylene powder, the plasticizer and the heat stabilizer. A polyethylene fiber was obtained in the same manner as in Example 1. In addition, it was 291 Pa.s when the melt viscosity of the obtained gel was measured. As a result of testing the tensile properties based on JIS L1013: 1999, the tensile modulus was greatly inferior to that of Example 1 even though the composition of the raw materials was equal.

[Example 2]
The gel obtained in Example 1 was processed into a sheet of 60 mm × 60 mm × 1 mm by press molding. This sheet was stretched by a batch-type simultaneous biaxial stretching machine at 120 ° C. and stretching conditions of 7 × 7 times. The obtained film was fixed to a metal frame and subjected to solvent extraction with methylene chloride to obtain a porous film having a viscosity average molecular weight of 700,000. A test piece of MD50 mm × TD50 mm was prepared and tested for tensile properties based on JIS K7127: 1999. As a result, the tensile strength at break was 1127 kgf / cm ² and the tensile modulus was 4126 kgf / cm ² .

[Example 3]
A porous membrane having a viscosity average molecular weight of 630,000 was obtained in the same manner as in Example 2 except that ultra high molecular weight polyethylene powder having a viscosity average molecular weight of 3,030,000 (DSM, Stamylan (registered trademark) UH210) was used. It was. A test piece of MD50 mm × TD50 mm was prepared and tested for tensile properties based on JIS K7127: 1999. As a result, the tensile strength at break was 1010 kgf / cm ² and the tensile modulus was 3448 kgf / cm ² .

[Comparative Example 2]
Implementation was performed except that the high molecular weight polyethylene powder having a viscosity average molecular weight of 300,000 was supplied from the beginning without being supplied later and melt-kneaded with the ultrahigh molecular weight polyethylene powder, the plasticizer and the heat stabilizer. A porous film having a viscosity average molecular weight of 620,000 was obtained in the same manner as in Example 2. A test piece of MD50 mm × TD50 mm was prepared and tested for tensile properties based on JIS K7127: 1999. As a result, the tensile strength at break was 686 kgf / cm ² and the tensile modulus was 3056 kgf / cm ² . Despite the equal composition of the raw materials, the tensile property test results were significantly inferior to the results of Example 2.

  The stretched polyolefin molded article obtained by the production method of the present invention has excellent tensile properties and excellent shape stability, and protects the characteristics of ultra-high molecular weight polyethylene, particularly as an engineering plastic, for protective use, for special materials, and for filtration. Or it can utilize suitably for separator uses, such as a lithium ion secondary battery and a fuel cell.

Claims (4)

A method for producing a stretched polyolefin article comprising an ultrahigh molecular weight polyethylene having a viscosity average molecular weight of 1,500,000 to 10,000,000 and a high molecular weight polyethylene having a viscosity average molecular weight of 100,000 to 1,000,000, the ultrahigh molecular weight polyethylene , After melt-kneading 5 to 40 parts of a plasticizer with respect to 1 part by weight of ultra high molecular weight polyethylene to form a gel having a melt viscosity of 1 to 240 Pa · s, the high molecular weight polyethylene is supplied to the gel and mixed. A method for producing a polyolefin stretch-molded product, wherein the resulting mixture is stretch-molded to obtain a polyolefin stretch-molded product.   2. The method for producing a stretched polyolefin molded article according to claim 1, wherein the gel formed by melt-kneading ultrahigh molecular weight polyethylene and a plasticizer has a melt viscosity of 10 to 200 Pa · s.   The method for producing a stretched polyolefin article according to claim 1 or 2, wherein the ultrahigh molecular weight polyethylene has a viscosity average molecular weight of 2 million to 4 million and an average particle diameter of 10 to 400 µm. The method for producing a stretched polyolefin article according to any one of claims 1 to 3, wherein the ultrahigh molecular weight polyethylene is an ultrahigh molecular weight polyethylene polymerized using the following olefin polymerization catalyst:
An olefin polymerization catalyst comprising a solid catalyst component [A] and an organometallic compound component [B], wherein the solid catalyst component [A] is represented by the following general formula (1)
^{_{M 1 E Mg G R 1 p}} R 2 q X r Y s ····· (1)
(In the above general formula (1), M ¹ is a metal atom included in the group consisting of Group 1, Group 2, Group 3, Group 12 and Group 13 of the periodic table, and R ¹ and R ² are carbon atoms. 2 to 20 hydrocarbon groups, X and Y are the same or different OR ³ , OSiR ⁴ R ⁵ R ⁶ , NR ⁷ R ⁸ , SR ⁹ , a functional group selected from halogen, R ³ and R ⁹ are carbon numbers 1 to 20 hydrocarbon groups, R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ are hydrogen atoms or hydrocarbon groups having 1 to 20 carbon atoms, E, G, p, q, r, and s are , E ≧ 0, G> 0, p ≧ 0, q ≧ 0, r ≧ 0, s ≧ 0, p + q> 0, 0 ≦ (r + s) / (E + G) ≦ 2, kE + 2G = p + q + r + s (k is M ¹ Valence).)
An organomagnesium compound soluble in a hydrocarbon solvent represented by the following general formula (2):
Ti (OR ¹⁰ ) _w Z _4-w (2)
(In the general formula (2), R ¹⁰ is a hydrocarbon group, Z is a halogen, and w is a number satisfying 0 ≦ w ≦ 4.)
In the solid catalyst component [A], the organometallic compound component [B] is represented by the following general formula (3).
AlR ¹¹ _f T _3-f (3)
(In the above general formula (3), R ¹¹ is a hydrocarbon group having 1 to 12 carbon atoms, T is a group selected from hydrogen, halogen, alkoxy, allyloxy and siloxy groups, and f is a number of 2 to 3. is there.)
An olefin polymerization catalyst obtained by mixing an organoaluminum compound represented by the formula: