KR100695336B1 - Propylene polymer with high melt strength and its manufacturing method - Google Patents

Abstract

The present invention relates to a propylene polymer having a high melt strength and a method for producing the same, and more particularly, to the presence of a solid titanium catalyst for olefin polymerization surface-treated with a silane compound having two or more double bonds, for example, two or more vinyl groups. Prepared by encapsulating the propylene monomer in the presence of a diene compound, using a prepolymerization catalyst prepared by encapsulating a high molecular weight monomer around the catalyst by prepolymerizing the olefin monomer and the diene compound. The present invention relates to a propylene polymer having a high melt strength and particularly suitable for foaming, and to a method for producing the same.

Description

Propylene polymer with high melt strength and its manufacturing method {PROPYLENE POLYMER HAVING HIGH MELT STRENGTH AND METHOD FOR PRODUCING THE SAME}

FIG. 1 shows whether or not the extension hardening phenomenon (phenomena in which the draw strength rapidly increases as the strain-rate speed is increased) of the propylene polymers prepared in Examples and Comparative Examples of the present invention. It is a graph showing.

The present invention relates to a propylene polymer having a high melt strength and a method for producing the same, and more particularly, to the presence of a solid titanium catalyst for olefin polymerization surface-treated with a silane compound having two or more double bonds, for example, two or more vinyl groups. Prepared by encapsulating the propylene monomer in the presence of a diene compound, using a prepolymerization catalyst prepared by encapsulating a high molecular weight monomer around the catalyst by prepolymerizing the olefin monomer and the diene compound. The present invention relates to a propylene polymer having a high melt strength and particularly suitable for foaming, and to a method for producing the same.

In general, plastics used for foam products include polyurethanes, polyolefins, polyvinyl chloride (PVC), ABS resins, urea resins, phenol resins and the like. Among them, polystyrene or polyurethane is mainly used for foaming. However, polystyrene has high elastic modulus and has high heat insulation and cushioning properties, and high magnification foam molding is possible to form a lightweight foam. In addition, since independent bubbles are formed, they are widely applied to food containers and the like. On the other hand, in the case of polyurethane, there is an advantage that can be produced a variety of foam through the appropriate selection of the monomer. Polyurethane flexible foams are used mainly for buffers and the like because they are excellent in touch, and rigid foams are mainly used as insulation for construction.

As described above, polystyrene and polyurethane have excellent properties as foaming materials, but they are not applicable to specific applications. Polystyrene has low heat resistance and oil resistance, so it is used when the operating temperature exceeds 100 ℃ or when it needs to be in contact with oil. This is difficult, and since polyurethane is difficult to secondary molding or recycling after foam molding, it is not applied to a food container.

 On the other hand, polypropylene has the advantage of high balance of mechanical properties, excellent oil resistance and heat resistance, and is also used in a wide range of areas such as automobile parts, films, and injection molded products, since secondary molding and recycling are possible. Due to the weak melt tension due to the structure there is a problem that it is difficult to secure a satisfactory formability compared to other plastics.

 Therefore, in order to overcome this, various methods for increasing the melt tension of polypropylene have been proposed, for example, by introducing a long chain branch into the polyolefin to reduce the attraction between the polymer chain in the processing process, easy flow (easy flow) and at the same time forming process, especially in the molding process requiring dimensional stability, such as large blow molding has been proposed a method for increasing the elasticity through physical crosslinking with adjacent chains have. In the method of preparing high elastic polyolefin by introducing such long branches, radicals are mainly formed in the polyolefins which have passed through the polymerization reactor through electron beam or reaction extrusion method, and the reaction is carried out again to form long branches in the chain polyolefin. US Pat. Nos. 5,368,919, 5,414,027, 5,541,236, 5,554,668, 5,591,785, and 5,731,362. However, the resin produced by using the above-described method has a disadvantage in that physical properties are excellent but radical forming apparatuses such as electron beam irradiation equipment are expensive and productivity is low due to low productivity. In addition, a method of introducing long branches into polypropylene by reacting organic peroxides with polypropylene under specific reaction conditions has been developed (US Pat. Nos. 5,416,139 and 4,525,257), but the reaction with the peroxide is batchwise. Due to the long manufacturing time there is a problem of low productivity. In addition, a method of physically blending polyethylene with polypropylene having a very low melt index has been proposed (US Pat. No. 4,365,044), but this method has a problem in that heat resistance is lowered due to a decrease in rigidity and a workability is lowered due to a low melt index. There is this. In addition, by modifying the surface of the catalyst in the preparation step of the catalyst and using a diene compound in the prepolymerization step, a high molecular weight monomer (macromonomer) is formed around the catalyst, and then the olefin monomer is used by the main polymerization of the olefin monomer. Although a method of preparing a polyolefin having high elasticity has been proposed (Korean Patent Publication No. 2003-55617), such a method alone has a limitation in increasing melt strength.

The present invention is to solve the problems of the prior art as described above, the object of the present invention, when compared to the existing polypropylene resin, the extension hardening phenomenon occurs when the extension viscosity is measured, the melt strength is very high In particular, the present invention provides a propylene polymer capable of exhibiting excellent molding stability and physical properties during foaming, vacuum molding, and blow molding, and a method of manufacturing the same.

According to the present invention, an electrode prepared by encapsulating a high molecular weight monomer around the catalyst by prepolymerizing an olefin monomer and a diene compound in the presence of a solid titanium catalyst for olefin polymerization surface-treated with a silane compound having two or more double bonds. A long branched, high melt strength propylene polymer is provided, which is prepared by subjecting a propylene monomer to the main polymerization in the presence of a diene compound using a polymerization catalyst.

The propylene polymer of the present invention has a high melt strength and is suitable for foaming, vacuum forming and blow molding. The propylene polymer has a density of 0.89 to 0.91 g / cm 3 and a melt index of 0.1 ° C. at 230 ° C. and 2.16 kg load according to ASTM D1238. It is especially preferable for foaming that it is -10 g / 10min. If the density is less than 0.89 g / cm 3, there is a fear that the structural stability of the foam deteriorates, if the density exceeds 0.91 g / cm 3, the weight of the foam is too outgoing can be limited. In addition, if the melt index is less than 0.1g / 10 minutes, there is a problem that the workability is poor to process into a foam, when the melt index exceeds 10g / 10 minutes there is a problem that the mechanical properties of the foam is deteriorated is not preferable.

In addition, the propylene polymer of the present invention is a foam, vacuum molding, and blow molding that the melt strength measured at the chamber temperature 140 ℃ of the strand coming out through the die of the capillary rheometer at 200 ℃ It is preferable for the use. If the melt strength is less than 600 mN, excellent molding stability and physical properties cannot be obtained during foaming, vacuum forming, and blow molding.

In addition, in the propylene polymer of the present invention, it is preferable that an extension hardening phenomenon occurs in which the tensile strength value increases rapidly when the pull-off speed has a predetermined value or more.

The propylene polymer of the present invention comprises 1 to 10% by weight of a polymer part derived from a high molecular weight monomer formed around the catalyst by prepolymerization, and a copolymer part 90 to 99 formed from a diene compound and a propylene monomer by main polymerization. It is preferable to comprise by weight%. If the amount of the polymer part derived from the high molecular weight monomer formed around the catalyst by prepolymerization is less than 1% by weight, the amount of long branches introduced into the polymer is too small to obtain the desired level of melt strength, 10 If the weight percentage is exceeded, the amount of long branches or mesh introduced into the polymer becomes too large, resulting in poor workability.

In the propylene polymer of the present invention, the content of the diene compound in the copolymer portion formed from the diene compound and the propylene monomer by the main polymerization is preferably 0.1 to 10% by weight. If the content of the diene compound in the copolymer portion by the main polymerization is less than 0.1% by weight, the amount of long branches introduced into the polymer is too small to obtain a desired level of melt strength, and if the content exceeds 10% by weight, the polymer Too much branching or netting introduced into the process leads to poor workability.

Further, according to the present invention, as a main catalyst, a high molecular weight monomer around the catalyst by prepolymerizing the olefin monomer and diene compound in the presence of a solid titanium catalyst for olefin polymerization surface-treated with a silane compound having two or more double bonds Prepolymerization catalyst prepared by encapsulating; Organometallic compounds of Group II or Group III metals of the periodic table as cocatalysts; And in the presence of an external electron donor there is provided a process for producing a long branched, high melt strength propylene polymer, characterized in that it is prepared by main polymerization of a diene compound and a propylene monomer.

In the propylene polymer manufacturing method of this invention, it is preferable to main-polymerize the mixture which consists of 0.1-10 weight% of said diene compounds, and 90-99.9 weight% of said propylene monomers. If the content of diene compound in the mixture used in the main polymerization is less than 0.1% by weight, the amount of long branches introduced into the polymer is too small to obtain a desired level of melt strength, and if it exceeds 10% by weight, The amount of long branches or meshes becomes too large, leading to poor workability.

The term "polymerization" in the present invention means not only the production of homopolymers of olefins, but also the production of copolymers of olefins with other alpha-olefins. In addition, in the present invention, the term "main polymerization" is a term used to distinguish the prepolymerization carried out at the time of preparing the catalyst, and means a polymerization step in which the propylene polymer obtained according to the present invention is finally formed.

In the production of the propylene polymer of the present invention, an olefin prepolymer prepared by prepolymerizing an olefin and a multifunctional compound in the presence of a solid complex titanium catalyst for olefin polymerization is used as a high molecular weight monomer capable of forming a branch. Copolymers of diene compounds and propylene monomers in the main polymerization, using catalysts in the form of encapsulation around the catalyst (hereinafter referred to as 'prepolymerization catalysts'), present as high molecular weight monomers around the prepolymerization catalyst. The olefin / polyfunctional compound in the prepolymer forms an entanglement with the copolymer by the main polymerization, and as a result, the melt strength of the propylene polymer is rapidly increased.

The prepolymerization catalyst usable in the production of the propylene polymer of the present invention is treated with a silane compound having two or more double bonds on the surface of the solid titanium catalyst for olefin polymerization, and then the olefin monomer is present in the presence of the surface treated catalyst. By prepolymerizing a diene compound, a high molecular weight monomer capable of forming a branch around the surface treated catalyst is polymerized and produced by encapsulating the catalyst. Prepolymerization catalysts in the form of a branched high molecular weight monomer usable in the production of the propylene polymer of the present invention encapsulated around the catalyst are described, for example, in Korean Patent Application No. 2001-85640 filed by the present applicant. Prepolymerization catalysts of the type described in the heading, which pretreat the surface of the solid titanium catalyst for olefin polymerization with a silane compound having two or more vinyl groups, and then It is prepared by encapsulating the high molecular weight monomer of the olefin / diene compound around the catalyst by prepolymerizing the olefin monomer and the diene compound. Such a prepolymerization catalyst has superior catalytic activity as compared to a conventional titanium catalyst, has a wide molecular weight distribution, enables the production of a polymer having high stereoregularity, and in particular, has a feature of forming a long branch in the polymer.

In the present invention, as the solid titanium catalyst for olefin polymerization used in the production of the prepolymerization catalyst, for example, US Patent Nos. 4,482,687, 4,277,372, 3,642,746, 3,642,772, 4,158,642, 4,148,756 Ordinary olefins described in Nos. 4,477,639, 4,518,706, 4,946,816, 4,866,022, 5,013,702, 5,124,297 and 4,330,649, European Patent 131,832, and Japanese Patent Laid-Open No. 63-54004. Both Ziegler-Natta catalysts for polymerization can be used, which can be prepared in various ways. For example, in the presence of an electron donor without active hydrogen, a magnesium compound having no reducing ability in the liquid state may be prepared by direct contact reaction with the liquid titanium compound, that is, by directly contacting each other in the liquid state. In the absence of an electron donor without active hydrogen, a solid catalyst may be formed of a magnesium compound and a titanium compound, and then contacted with an electron donor.

Among the various methods for producing the solid titanium catalyst for olefin polymerization used in the preparation of the prepolymerization catalyst, the most common method is to contact a magnesium compound and a titanium compound containing at least one halogen, and if necessary There is a method of treating the product with an electron donor. Such methods are described, for example, in JP 2,230,672, 2,504,036, 2,553,104 and 2,605,922 and JP 51-28189, 51-136625 and 52-87486. It is described.

As a preferred example of the method for preparing a solid titanium catalyst for olefin polymerization, (i) dissolving a magnesium compound having no reducibility in an electron donor to prepare a magnesium compound solution, (ii) magnesium solution is a transition metal compound, a silicon compound Solid particles comprising reacting with a tin compound or a mixture thereof to precipitate solid particles, (i) reacting the precipitated solid particles with a titanium compound and an electron donor, and washing the resultant with a hydrocarbon solvent. The method of manufacturing a complex titanium catalyst is mentioned, It is preferable to use the magnesium supported solid complex titanium catalyst manufactured by such a method for manufacture of the prepolymerization catalyst used at the time of the propylene polymer manufacture of this invention.

In the preparation of the above-mentioned solid complex titanium catalyst, the non-reducible magnesium compound includes magnesium halides such as magnesium chloride, magnesium bromide, magnesium iodide and magnesium fluoride; Alkoxymagnesium halides such as methoxymagnesium chloride, ethoxymagnesium chloride, isopropoxymagnesium chloride, butoxymagnesium chloride and octoxymagnesium chloride; Aryloxymagnesium halides such as phenoxyshimamium chloride and methylphenoxymagnesium chloride; Alkoxy magnesium such as ethoxy magnesium, isopropoxy magnesium, butoxy magnesium and octoxy magnesium; Aryloxymagnesium, such as phenoxyshimamagnesium and dimethylphenoxymagnesium; And magnesium salts of carboxylic acids such as lauryl magnesium and magnesium stearate. Such magnesium compound may be used in the form of a complex with another metal or with a mixture with other metals, or may be used as a mixture of two or more kinds of magnesium compounds. Preferred magnesium compounds include hydrogen-containing magnesium compounds, magnesium chloride, alkoxymagnesium chlorides having C1 to C14 alkoxy groups, and aryloxymagnesium chlorides having C5 to C20 aryloxy groups.

The magnesium compounds may be represented by a simple chemical formula, but sometimes the magnesium compound may not be expressed by a simple formula depending on the preparation method thereof. These are generally regarded as mixtures of the above compounds. For example, a method of reacting magnesium metal with alcohol or phenol in the presence of halosilane, phosphorus pentachloride, or thionyl chloride, pyrolysis of Grignard reagent, or hydroxyl group, carbonyl group, ester bond, ether bond, etc. Compounds obtained by the decomposition method, which are considered to be a mixture of various compounds according to the reagent or the reactivity thereof, these magnesium compounds may also be used in the preparation of the solid titanium catalyst for olefin polymerization used in the preparation of the prepolymerization catalyst. .

In the preparation of the solid titanium catalyst for olefin polymerization, at least one electron donor selected from the group consisting of alcohols, organic carboxylic acids, aldehydes, amines and mixtures thereof, in the presence or absence of a hydrocarbon compound, the magnesium compound as described above Reaction with mixing and heating to prepare a magnesium compound solution. Examples of the hydrocarbon solvent usable at this time include aliphatic hydrocarbons such as pentane, hexane, heptane, octane, decane, dodecane and kerosene; Alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane and methylcyclohexane; Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene and cymene; And halogenated hydrocarbons such as dichloroethane, dichloropropane, dichloroethylene, trichloroethylene, carbon tetrachloride and chlorobenzene.

In the case of preparing the magnesium compound solution, when the hydrogen-containing magnesium compound is dissolved in a hydrocarbon solvent and the alcohol is mixed and reacted as an electron donor, the ratio of the amount of the magnesium compound and the alcohol is used, although the amount and type of the magnesium compound and the hydrocarbon solvent are used. Although the amount varies depending on, it is preferable to use at least 0.5 mol, preferably about 1.0-20 mol, more preferably about 2.0-10 mol of alcohol per mol of magnesium compound.

In the case where an aliphatic hydrocarbon or an alicyclic hydrocarbon is used as the hydrocarbon solvent, the relative amount of alcohol is generally as described above. However, if an alcohol having 6 or more carbon atoms is used, at least 0.5 mole, preferably 1.0 mole or more, per mole of magnesium compound The use of alcohol can dissolve the halogen-containing magnesium compound, in which case a catalyst component having high activity can be obtained using a small amount of alcohol. If aliphatic or cycloaliphatic hydrocarbons are used as hydrocarbon solvents, if alcohols having 5 or less carbon atoms are used, the amount of alcohol used should be at least about 15 moles per mole of halogen-containing magnesium compound, resulting in activity of the resulting catalyst It is lower than when using 6 or more alcohols. On the other hand, when an aromatic hydrocarbon is used as the hydrocarbon solvent, the hydrogen-containing magnesium compound can be dissolved using about 20 moles, preferably about 1.5 to 12 moles of alcohol, regardless of the type of alcohol.

The reaction conditions of the magnesium compound and the alcohol as the electron donor may vary depending on the type of the magnesium compound and the alcohol, for example, about 15 to about 5 at about 30 to 200 ° C, preferably about 60 to 150 ° C. Time, preferably from about 30 minutes to about 3 hours.

   Alcohols used as electron donors include 2-methylpentanol, 2-ethylbutanol, n-heptanol, n-octanol and 2-ethylhexanol having at least 6 carbon atoms, preferably 6-20 carbon atoms. Aliphatic alcohols such as decanol, dodecanol, tetradecyl alcohol, undecenol, oleyl alcohol and stearyl alcohol; Alicyclic alcohols such as cyclohexanol and methylcyclohexanol; And aromatic alcohols such as benzyl alcohol, methyl benzyl alcohol, isopropylene benzyl alcohol, α-methylbenzyl alcohol and α, α-dimethylbenzyl alcohol. Alcohols having 5 or less carbon atoms include methanol, ethanol, propanol, butanol, ethylene glycol and methylcarbitol.

The magnesium compound solution prepared as described above is crystallized into a spherical solid by reacting with a transition metal compound such as a titanium compound, a silicon compound, a tin compound, or a mixture thereof. At this time, the amount of the transition metal compound, etc. may vary as needed, and in general, the appropriate amount of the transition metal compound, silicon compound, tin compound, or mixtures thereof per mole of magnesium compound is 0.1 to 20 moles, preferably Is 0.1-10 mol, More preferably, it is the range of 0.2-2 mol.

When the magnesium compound solution is reacted with a transition metal compound or the like to crystallize the magnesium compound in the liquid state, the shape and size of the magnesium carrier vary depending on the reaction conditions. The preferred contact reaction temperature is about -70 ° C to 200 ° C. However, in order to obtain the form of granular or spherical particles, it is generally desirable to avoid high temperatures during mixing, whereas if the contact temperature is too low, precipitation of solid products does not occur, so the reaction is at a temperature of about 20 ° C. to 150 ° C. It is preferable to carry out.

A solid complex titanium catalyst is prepared by reacting a magnesium compound in a solid particle state obtained by reacting a magnesium compound solution with a transition metal compound and the like with a titanium compound and an electron donor. Examples of electron donors used in this step are generally oxygen-containing electron donors such as water, alcohols, phenols, ketones, aldehydes, carboxylic acids, esters, ethers and acid amides or ammonia, amines, nitriles And nitrogen-containing electron donors such as isocyanates, specific examples of which include methanol, ethanol, propanol, pentanol, hexanol, octanol, dodecanol, octadecyl alcohol, benzyl alcohol, phenylethyl alcohol, cumyl alcohol and iso Alcohols containing 1 to 18 carbon atoms, such as propylbenzyl alcohol; Ketones having 6 to 15 carbon atoms which may contain alkyl groups such as phenol, cresol, xylene, ethylphenol, propylphenol, cumylphenyl and naphthol; Aldehydes containing 2 to 15 carbon atoms such as acetaldehyde, propionaldehyde, octylaldehyde, benzaldehyde, tolualdehyde and naphtholaldehyde; Methyl formate, methyl acetate, ethyl acetate, vinyl acetate, propyl acetate, octyl acetate, cyclohexyl acetate, ethyl propionate, methyl butyrate, ethyl valeric acid, methyl chloroacetate, ethyl dichloroacetate, methyl methacrylate, ethyl crotonate, cyclo Ethyl hexane carboxylate, phenyl benzoate, benzyl benzoate, methyl toluate, ethyl toluate, amyl toluate, ethyl ethyl benzoate, methyl aniseate, ethyl aniseate, ethyl ethoxybenzoate, γ-butyrolactone, δ-valerolactone, coumarin, phthalide, cyclohexyl acetate, ethyl propionate, methylbutyrate, methylbarate, methylchloroacetate, ethyldichloroacetate, methylmethacrylate, ethylcycloate, phenylbenzoate, methyltolu Ate, ethyltoluate, propylbenzoate, butylbenzoate, cyclohexylbenzoate, amyltoluate, ethylene carbonate and carbonate Organic acid esters containing from 2 to 18 carbon atoms, such as ethylene acid; Acid halides containing 2 to 15 carbon atoms, such as acetyl chloride, benzyl chloride, toluic acid chloride, and anisic acid chloride; Ethers such as methyl ether, ethyl ether, isopropyl ether, butyl ether, amyl ether, tetrahydrofuran, anisol and diphenyl ether; Amines such as methylamine, ethylamine, diethylamine, tributylamine, piperidine, tribenzylamine, aniline, pyridine, pinolin and tetramethylethylenediamine; And nitriles such as acetonitrile, benzonitrile and tolunitrile, and compounds such as aluminum, silicon, tin, etc. containing the functional groups as described above in the molecule. Also, acetates, propionates, n- of monoethylene glycol (MEG), diethylene glycol (DEG), triethylene glycol (TEG), polyethylene glycol (PEG), monopropylene glycol (MPG) and dipropylene glycol (DPG) And ester derivatives such as iso-butyrate, benzoate, toluate and the like can be preferably used. Examples of such ester derivatives include monoethylene glycol monobenzoate, monoethylene glycol dibenzoate and diethylene glycol monobenzo. Eight, diethylene glycol dibenzoate, triethylene glycol monobenzoate, triethylene glycol dibenzoate, monopropylene glycol monobenzoate, dipropylene glycol monobenzoate, dipropylene glycol dibenzoate, tripropylene glycol monobenzo Eight, etc. Electron donors as described above can be used as mixtures of two or more. However, such electron donors are not always necessary as starting materials and may be used in the form of adducts or complexes of other compounds. The amount of the electron donor can be appropriately changed, but about 0.01 to 10 mol, preferably about 0.01 to 5 mol, more preferably about 0.05 to 1 mol per mol of the magnesium compound.

The liquid titanium compound to react with the magnesium compound in the solid particle state is a tetravalent titanium compound represented by the general formula Ti (OR) _m X _4-m (wherein R represents an alkyl group having 1 to 10 carbon atoms and X represents a halogen atom). and m is an integer of 0 ≦ m ≦ 4). Examples of such titanium compounds include titanium tetrahalides such as TiCl ₄ , TiBr ₄ and TiI ₄ ; Ti (OCH ₃ ) Cl ₃ , Ti (OC ₂ H ₅ ) Cl ₃ , Ti (OC ₄ H ₉ ) Cl ₃ , Ti (OC ₂ H ₅ ) Br ₃ and Ti (O (iC ₂ H ₅ )) Br ₃ Halogenated alkoxytitanium such as titanium; Dihalogenated alkoxytitanium such as Ti (OCH ₃ ) ₂ Cl ₂ , Ti (OC ₂ H ₅ ) ₂ Cl ₂ , Ti (OC ₄ H ₉ ) ₂ Cl ₂ and Ti (OC ₂ H ₅ ) ₂ Br ₂ ; Monohalogenated alkoxytitanium such as Ti (OCH ₃ ) ₃ Cl, Ti (OC ₂ H ₅ ) ₃ Cl, Ti (OC ₄ H ₉ ) ₃ Cl and Ti (OC ₂ H ₅ ) ₃ Br; Tetraalkoxy titanium such as Ti (OCH ₃ ) ₄ , Ti (OC ₂ H ₅ ) ₄ , Ti (OC ₄ H ₉ ) _4, and the like. Among these titanium compounds, titanium tetrahalide is preferable, and titanium tetrachloride is particularly preferable among titanium tetrahalide. Such titanium compounds are used in an amount of at least 1 mole, typically about 3 to 200 moles, preferably about 5 to 100 moles, per mole of magnesium compound. When contacting a magnesium compound with a liquid titanium compound, it is advisable to mix at a low temperature and then slowly increase the reaction temperature, for example, by contacting the two compounds at -70 ° C to about 50 ° C so as not to react rapidly. Slowly raise the reaction temperature and react for 50 hours at a temperature of 50 ~ 150 ℃. After the reaction is complete, the resultant is washed until free titanium is not detected with the hydrocarbons used in the polymerization. It is possible to produce a solid titanium catalyst of excellent performance by the above catalyst production method.

In the present invention, the solid titanium catalyst for olefin polymerization used in the preparation of the prepolymerization catalyst has a molar ratio of halogen / titanium of about 4 or more, more preferably about 5 or more, most preferably about 8 or more, and magnesium The molar ratio of / titanium is about 3 or more, preferably about 5-50, and the molar ratio of electron donor / titanium is about 0.2-6, preferably about 0.4-3, more preferably about 0.8-2. Preferably, it is also preferable not to substantially release the titanium compound by hexane washing at room temperature. In addition, the specific surface area of the solid is preferably 10 m 2 / g or more, preferably about 50 m 2 / g or more, and more preferably 100 m 2 / g or more. In addition, it is preferable that the X-ray spectrum of a solid titanium catalyst shows an amorphous characteristic irrespective of starting magnesium, or it is more amorphous than the commercial grade of normal magnesium halide.

In order to prepare the prepolymerization catalyst used in the production of the propylene polymer of the present invention, first, the surface of the solid complex titanium catalyst is treated with two or more double bonds, preferably with a silane compound having a vinyl group. The divinyl silane compound preferably used at this time is divinyl dimethyl silane, divinyl diphenyl silane, divinyl diethyl silane, divinyl. Divinyl diisobutyl silane, divinyl silane dihydride, and the like. For the treatment of the catalyst surface, 2 to 200 mol of the silane compound having two or more double bonds per mol of the magnesium compound is used. This surface treatment can be carried out by subjecting the solid titanium catalyst to a silane compound having two or more double bonds by contact reaction at -70 to 50 ° C in the presence or absence of a solvent.

The prepolymerization catalyst used in the production of the propylene polymer of the present invention is obtained by prepolymerizing the olefin monomer and the diene compound in the presence of the surface treated solid titanium catalyst as described above. The prepolymerization process is carried out by reacting an olefin monomer with a diene compound at a temperature of -50 ° C to 50 ° C in the presence of the surface treated solid titanium catalyst, alkylaluminum and electron donor, whereupon it is present on the catalyst surface. The double bond-containing silane compounds and the olefin monomer and the diene compound react together to form a high molecular weight monomer on the surface of the catalyst. This high molecular weight monomer consists of an olefin, a double bond containing silane compound for surface treatment, and a diene compound, by which the catalyst surface is encapsulated. As content of the olefin, the diene compound, and the double bond containing silane compound in the high molecular weight monomer thus produced, olefin is 1 to 99 weight%. The diene compound is preferably 0.01 to 10% by weight, and the double bond-containing silane compound is 0.001 to 1% by weight, the olefin is 70 to 95% by weight, the diene compound is 0.1 to 5% by weight, and the double bond-containing silane compound is It is preferable that it is 0.01 to 1 weight%. As the olefin monomer used in this prepolymerization step, at least one selected from ethylene, propylene, 1-butene, 1-hexene and 1-octene is preferable, and as the diene compound, 1,3-butadiene, 1,5- Hexadiene, 1,7-octadiene, 1,9-decadiene, 1,13-tetradecadiene and the like are preferable.

The high molecular weight monomer formed around the catalyst by the prepolymerization as described above reacts with the propylene monomer and the diene compound in the subsequent main polymerization to form a long chain branch or a network. It is preferable that the molecular weight of this high molecular weight monomer is 500-100,000, It is especially preferable that the molecular weight 1000-10,000 can show the outstanding superposition | polymerization ability in this polymerization.

The prepolymerization catalyst prepared as described above is advantageously used for the polymerization of olefins such as ethylene, propylene, 1-butene, 3-methyl-1-butene, 4-methyl-1-pentene, vinylcycloalkane or cycloalkene. In particular, this prepolymerization catalyst is used for the polymerization of α-olefins having three or more carbon atoms, copolymerization of each other, copolymerization with less than 20 mol% of ethylene, and polyunsaturated compounds such as conjugated or nonconjugated dienes. It is useful for copolymerization of.

The propylene polymer of the present invention is prepared by subjecting the propylene monomers to the main polymerization in the presence of a diene compound using the prepolymerization catalyst prepared as described above. This main polymerization reaction is preferably carried out in the presence of an organometallic compound and an external electron donor of a Group II or Group III metal of the periodic table as a cocatalyst.

  Examples of organometallic compounds preferably used as cocatalysts in the main polymerization include trialkylaluminum such as triethylaluminum and tributylaluminum; Trialkenyl aluminum, such as triisoprenyl aluminum; Dialkyl aluminum alkoxides such as diethyl aluminum ethoxide and dibutyl aluminum butoxide; Alkyl aluminum sesquihalides such as ethyl aluminum sesquiethoxide and butyl aluminum sesquiethoxide; And alkylaluminum dihalides such as ethylaluminum dichloride, propylaluminum dichloride and butylaluminum dibromide, diethylaluminum hydride and dialkylaluminum hydrides such as dibutylaluminum hydride and dibutylaluminum hydride, ethylaluminum Partially alkoxylated and halogenated alkylaluminums such as oxychloride, butylaluminum butoxychloride and ethylaluminum ethoxybromide.

As the external electron donor used in the present polymerization, an external electron donor material commonly used in olefin polymerization may be used. These external electron donors are mainly used to optimize the activity and stereoregularity of the catalyst in the polymerization of olefins, and examples thereof include organic acids, organic acid anhydrides, organic acid esters, alcohols, ethers, aldehydes, ketones, silanes, amines, amines. And organic compounds containing oxygen, silicon, nitrogen, sulfur and phosphorus atoms such as oxides, amides, diols and phosphate esters, and mixtures thereof. Particularly preferred external electron donors are organosilicon compounds with alkoxy groups, i.e. alkoxysilane compounds, examples of which are aromatic silanes such as diphenyldimethoxysilane, phenyltrimethoxysilane, phenylethyldimethoxysilane and phenylmethyldimethoxysilane. , Isobutyltrimethoxysilane, diisobutyldimethoxysilane, diisopropyldimethoxysilane, di-t-butyldimethoxysilane, t-butyltrimethoxysilane, cyclohexylmethyldimethoxysilane, dicyclopentyldimeth Aliphatic silanes such as methoxysilane, dicyclohexyldimethoxysilane, 2-norbornanetriethoxysilane, 2-norbornanemethyldimethoxysilane, vinyltriethoxysilane and the like and mixtures thereof, and particularly among the above silane compounds, Branched alkyldialkoxysilanes such as diisobutyldimethoxysilane or cycloalkyldialkoxysilanes such as dicyclopentyldimethoxysilane are effective. The external electron donor compounds may be used alone or in combination of two or more thereof.

As the diene compound polymerized together with the propylene monomer in the main polymerization, a diene compound commonly used for olefin polymerization may be used, and examples thereof include 1,3-butadiene, 1,5-hexadiene, and 1,4. Hexadiene, 1,7-octadiene, cyclopentadiene, cyclohexadiene, cyclooctadiene, 1,9-decadiene, 1,13-tetradecadiene, and the like, and 1,7-octadiene. This is particularly preferred. The diene compounds may be used alone or in combination of two or more thereof.

In the production of the propylene polymer of the present invention, when the main polymerization is carried out in a liquid phase, an inert solvent such as hexane, heptane or kerosene may be used as the reaction solvent, but the olefin itself may also serve as a reaction solvent. The preferred concentration of the prepolymerization catalyst in the polymerization system is preferably about 0.001 to 5 mmol, preferably about 0.001 to 0.5 mmol, based on 1 liter of solvent in the case of liquid phase polymerization, and in the case of gas phase polymerization, In this case, it is preferable to set it to about 0.001 to 5 mmol, preferably about 0.001 to 1.0 mmol, and more preferably 0.01 to 0.5 mmol, per 1 L of the polymerization zone. In addition, the use ratio of the promoter is preferably about 1 to 2,000 moles, preferably about 5 to 500 moles, per mole of titanium atoms in the prepolymerization catalyst, in terms of organometallic atoms in the promoter, and the use ratio of the external electron donor is When calculated as nitrogen or silicon atoms, it is preferable to set it as about 0.001-10 mol, preferably about 0.01-2 mol, especially preferably 0.05-1 mol per mol of organometallic atoms in the cocatalyst.

In the preparation of the propylene polymer of the present invention, the main polymerization reaction proceeds in the same manner as in the olefin polymerization using a conventional Ziegler-type catalyst, in particular, substantially in the absence of oxygen and water. The main polymerization reaction may be carried out preferably at a temperature of about 20 to 200 ° C, more preferably at a temperature of about 50 to 180 ° C and a pressure of atmospheric pressure to 100 atm, preferably at a pressure of about 2 to 50 atm. In addition, this main polymerization reaction can be carried out batchwise, semibatch or continuously, and it is also possible to carry out the polymerization by two or more steps having different reaction conditions.

The present invention may be understood in more detail by the following examples, but the following examples are merely examples for illustrating the present invention and are not intended to limit the protection scope of the present invention.

[Examples and Comparative Examples]

Example 1

Preparation of Prepolymerization Catalyst

Step 1: Preparation of Magnesium Compound Solution

Into a 1.0 liter reactor equipped with a mechanical stirrer replaced with a nitrogen atmosphere, a mixture of 15 g of MgCl ₂ , 4.2 g of AlCl ₃ and 550 ml of toluene was added and stirred at 400 rpm. Then, 1.5 ml of silicon tetraethoxide and 3.0 ml of tributyl phosphate were added thereto, and the temperature was raised to 105 ° C. and reacted for 4 hours. The homogeneous solution obtained after the reaction was completed was cooled to room temperature.

Step 2: preparing a solid carrier

The magnesium solution prepared in step 1 was transferred to a 1.6 liter reactor maintained at 13 ° C. After stirring was maintained at 350 rpm, 15.5 mL of TiCl ₄ was added thereto, and the temperature of the reactor was raised to 90 ° C. Solid carriers were produced during this process. The reaction was continued at 90 ° C. for 1 hour and then stirring was stopped to allow precipitation of the resulting solid support. After the precipitation was completed, the solid carrier from which the supernatant was separated was washed twice with 75 ml of toluene.

Step 3: Preparation of Solid Titanium Catalyst

100 mL of toluene and 100 mL of TiCl _{4 were} added to the solid carrier, and the temperature of the reactor was raised to 110 ° C. and heated for 1 hour. After the stirring was stopped, the solid carrier was precipitated, the supernatant was separated, 100 ml of toluene and 100 ml of TiCl ₄ were added thereto, and 2.9 ml of diisobutyl phthalate was added at 70 ° C. The temperature of the reactor was again raised to 120 ° C. and stirred for 1 hour. After the stirring was stopped, the supernatant was separated, 100 ml of toluene was injected, and the temperature of the reactor was lowered to 70 ° C. and stirred for 30 minutes. After the reactor was stopped and the supernatant was separated, 100 ml of TiCl ₄ was injected and stirred at 70 ° C. for 30 minutes to prepare a solid titanium catalyst.

Step 4: surface treatment of solid titanium catalyst

The solid titanium catalyst prepared above was washed five times with 75 ml of purified hexane, and 500 ml of hexane and 50 ml of divinyldimethylsilane were added and reacted at room temperature for 1 hour. The prepared catalyst was stored after drying in a nitrogen atmosphere. The surface-treated solid titanium catalyst contained 2.5% by weight of titanium atoms.

Step 5: prepolymerization

After washing the reactor with a capacity of 2 liters with propylene, 3 g of the catalyst obtained in step 4 and 1000 ml of hexane were added to the reactor. Next, triethylaluminum in an amount such that the Al / Ti molar ratio of Ti in the catalyst is 12 and cyclohexylmethyldimethoxysilane in an amount of 12 Si / Ti molar ratio of Ti in the catalyst was injected into the reactor. Thereafter, propylene was injected into the reactor at a rate of 20 cc / min at a rate of 1.5 g based on the weight of 1 g of the catalyst at 5 ° C., and the first prepolymerization was performed for 1 hour. Next, 37.3 cc of 1,7-octadiene was injected, and then an amount of 45 g of ethylene per 1 g of the catalyst was injected at a rate of 50 cc / min to carry out the second prepolymerization for 3 hours. A prepolymerization catalyst in the form encapsulated with a molecular weight monomer was obtained. In the prepolymerization catalyst thus obtained, the amount of polyethylene in the high molecular weight monomer polymerized around the catalyst was 45 g per 1 g of the catalyst.

Main polymerization

In a 2 L stainless steel reactor equipped with a stirrer and a heating / cooling device, 3 g of the prepolymerization catalyst (based on polyethylene by weight of the prepolymerization catalyst), 7 cc of triethylaluminum 1M solution as a promoter, and dicyclopentyldimethoxysilane as an electron donor 7 cc of 0.1 M solution, 1200 cc of liquid propylene, 1 cc of 1,7-octadiene, and 1000 cc of hydrogen as molecular weight regulators were added, followed by propylene main polymerization at 70 ° C. for 16 minutes to obtain 341 g of propylene polymer having long branches. Got it. The prepolymer (polyethylene) content in the resulting propylene polymer was 0.88% by weight.

For the propylene polymer prepared as above, the melt index, the die swell and the melt strength were measured by the following method, and the results are shown in Table 1 below. In addition, to find out whether or not the extension hardening phenomenon (a phenomenon in which the draw strength rapidly increases as the strain rate is increased) of the produced propylene polymer, the strain rate (pull-off speed) The stretching strength was measured while increasing, and the results are shown in FIG. 1.

-Melt index

Measured at 230 ° C and 2.16 kg load in accordance with ASTM D1238.

Die swell

When measuring the melt index, measure the diameter of the molten resin that passes through the orifice.

-Melt strength and extension strength measurement

Using a melt and extension strength measuring device (SMER; Samsung Melt Tension Rheometer) described in Korean Patent Application No. 2001-30112, the strands exiting through the die of the capillary rheometer at 200 ° C. were subjected to a chamber temperature of 140 ° C. Measured at ℃. (L / D of die: 16, acceleration ratio: 1mm / sec)

Example 2

326 g of a propylene polymer having a long branch introduced therein was obtained in the same manner as in Example 1, except that 2 cc of 1,7-octadiene was injected in the main polymerization step. The prepolymer (polyethylene) content in the resultant propylene polymer was 0.92% by weight.

For the propylene polymer prepared as above, the melt index, die swell and melt strength were measured in the same manner as in Example 1, and the results are shown in Table 1 below. In addition, the draw strength was measured while increasing the pull-off speed of the produced propylene polymer, the results are shown in FIG.

Example 3

Except that 3 cc of 1,7-octadiene was injected in the main polymerization step, 316 g of propylene polymer having long branches introduced was obtained by the same method as in Example 1. The prepolymer (polyethylene) content in the resultant propylene polymer was 0.95% by weight.

For the propylene polymer prepared as above, the melt index, die swell and melt strength were measured in the same manner as in Example 1, and the results are shown in Table 1 below. In addition, the draw strength was measured while increasing the pull-off speed of the produced propylene polymer, the results are shown in FIG.

Example  4

In the main polymerization step, 0.67 g of the prepolymerization catalyst was used, 1cc of 1,7-octadiene, 300cc of hydrogen was injected, and the polymerization time was 60 minutes. As a result, 121 g of a propylene polymer having long branches introduced therein was obtained. The prepolymer (polyethylene) content in the resulting propylene polymer was 0.56% by weight.

For the propylene polymer prepared as above, the melt index, die swell and melt strength were measured in the same manner as in Example 1, and the results are shown in Table 1 below. In addition, the draw strength was measured while increasing the pull-off speed of the produced propylene polymer, the results are shown in FIG.

Example 5

72 g of propylene polymer having long branches was obtained in the same manner as in Example 4, except that 0.67 g of the prepolymerization catalyst was used in the main polymerization step and 9 cc of 1,7-octadiene was injected. The prepolymer (polyethylene) content in the resultant propylene polymer was 0.93% by weight.

For the propylene polymer prepared as above, the melt index, die swell and melt strength were measured in the same manner as in Example 1, and the results are shown in Table 1 below. In addition, the draw strength was measured while increasing the pull-off speed of the produced propylene polymer, the results are shown in FIG.

Comparative Example 1

358 g of a propylene polymer was obtained by the same method as Example 1, except that 1,7-octadiene was not injected in the main polymerization step. The prepolymer (polyethylene) content in the resultant propylene polymer was 0.84% by weight.

For the propylene polymer prepared as above, the melt index, die swell and melt strength were measured in the same manner as in Example 1, and the results are shown in Table 1 below. In addition, the draw strength was measured while increasing the pull-off speed of the produced propylene polymer, the results are shown in FIG.

Comparative Example 2

In step 5 (prepolymerization step) of the prepolymerization catalyst preparation step, except that the second prepolymerization using ethylene and 1,7-octadiene was not carried out in the same manner as in Example 1 A polymerization catalyst was obtained.

383 g of propylene polymer was obtained in the same manner as in Example 1, except that 2 cc of 1,7-octadiene was injected in the main polymerization step using 0.030 g (polypropylene standard) of the prepolymer catalyst obtained as described above. Got.

For the propylene polymer prepared as above, the melt index, die swell and melt strength were measured in the same manner as in Example 1, and the results are shown in Table 1 below. In addition, the draw strength was measured while increasing the pull-off speed of the produced propylene polymer, the results are shown in FIG.

TABLE 1

Melt Index (g / 10min) Die swell (mm) Melt strength (mN) Example 1 0.34 5.2 641 Example 2 0.38 5.0 726 Example 3 0.37 4.8 628 Example 4 0.32 5.4 622 Example 5 0.31 4.2 605 Comparative Example 1 0.30 4.9 498 Comparative Example 2 1.0 2.8 60

As can be seen from Table 1, in Examples 1 to 5 using 1,7-octadiene in the main polymerization, melting compared with the case of Comparative Example 1 in which 1,7-octadiene was not used in the main polymerization. Propylene polymers with significantly high strength were produced. Further, in Examples 1 to 5 using a diene compound and a catalyst prepolymerized with ethylene, the melt strength was lower than that of Comparative Example 2, which showed only the properties of general polypropylene by using a catalyst prepolymerized only with propylene. At least ten times higher propylene polymers were prepared.

As described above, according to the present invention, it is possible to obtain a propylene polymer that is much superior to the melt strength of the existing resin. Since the propylene polymer having such improved melt strength exhibits excellent moldability during foam molding, the foaming ratio and foam cell density of the foam are high, the melt rigidity of the cell is high, and the retention of the cell is increased to make various foamed molded articles. In addition, since the melt strength is not improved by the conventional crosslinking method, there is an advantage that the properties of the thermoplastic resin can be maintained as it is and can be recycled.

Claims (8)

Using a prepolymerization catalyst prepared by encapsulating a high molecular weight monomer around the catalyst by prepolymerizing an olefin monomer and a diene compound in the presence of a solid titanium catalyst for olefin polymerization surface-treated with a silane compound having two or more double bonds. A long branched propylene polymer having a high melt strength, characterized in that it is prepared by main polymerization of a propylene monomer in the presence of a diene compound. The high melt strength propylene polymer according to claim 1, wherein the density is 0.89 to 0.91 g / cm 3, and the melt index measured at 230 ° C. and 2.16 kg load according to ASTM D1238 is 0.1 to 10 g / 10 minutes. The high melt strength propylene polymer according to claim 1, wherein the melt coming out through the die of the capillary rheometer at 200 ° C. has a melt strength of 600 mN or more measured at a chamber temperature of 140 ° C. 3. The propylene polymer of high melt strength according to claim 1, wherein the point after thickening phenomenon is expressed. 2. The polymer composition according to claim 1, wherein 1 to 10% by weight of the polymer portion derived from the high molecular weight monomer formed around the catalyst by prepolymerization, and 90 to 99 weight of the copolymer portion formed from the diene compound and the propylene monomer by the main polymerization. A propylene polymer having high melt strength, comprising%. The propylene polymer of high melt strength according to claim 1, wherein the content of the diene compound in the copolymer portion formed from the diene compound and the propylene monomer by main polymerization is 0.1 to 10% by weight. Prepolymerization prepared by encapsulating a high molecular weight monomer around the catalyst by prepolymerizing the olefin monomer and the diene compound in the presence of a solid titanium catalyst for olefin polymerization surface-treated with a silane compound having two or more double bonds as a main catalyst. catalyst; Organometallic compounds of Group II or Group III metals of the periodic table as cocatalysts; And long-branched introduced high melt strength propylene polymer, which is prepared by main polymerization of a diene compound and a propylene monomer in the presence of an external electron donor. The method for producing a propylene polymer having high melt strength according to claim 7, wherein the mixture comprising 0.1 to 10% by weight of the diene compound and 90 to 99.9% by weight of the propylene monomer is polymerized.

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