JPH0820685A - Flexible polyolefin-based resin composition and film using the same - Google Patents

Abstract

PURPOSE:To obtain a polyolefin-based resin composition capable of forming a film excellent in strength, recovering properties from deformation and stress relaxation characteristics and having flexibility, extensibility and heat resistance and the film using the composition. CONSTITUTION:This polyolefin-based resin composition comprises 50-95wt.% polyolefin-based resin A and 50-5wt.% polyolefin-based resin B or polyethylene- based resin C. Furthermore, the film using this resin composition is prepared. The polyolefin-based resin A is a copolymer of the following components (i) and (ii): (i) propylene and/or a combination of the propylene with an alpha-olefin and (ii) ethylene and/or a combination of the ethylene with the alpha-olefin. The polyolefin-based resin B is a polyolefin resin having a random branched molecular structure and the polyethylene-based resin C is obtained by polymerization using a metallocene compound containing a tetravalent transition metal as a catalyst.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin resin composition capable of forming a film which is excellent in strength, deformation recovery property and stress relaxation property, and is excellent in flexibility, extensibility and heat resistance. More specifically, the present invention contains a polypropylene-based resin having flexibility, and a polyolefin-based resin having a random branched molecular structure or a polyethylene-based resin polymerized using a metallocene compound containing a tetravalent transition metal as a catalyst. TECHNICAL FIELD The present invention relates to a resin composition and a film using the same.

[0002]

2. Description of the Related Art Plasticized vinyl chloride (hereinafter abbreviated as plasticized PVC) is a resin which is flexible and stretchable and suitable for various films. When a film is made from the plasticized PVC, the film generally contains a large amount of the plasticizer, so that the plasticizer migrates to the surface and adversely affects the physical properties and the like. In recent years, environmental issues have become important,
The use of plasticized PVC, a halogen-containing polymer, is controversial in all fields and there is a great deal of research into alternative materials.

For this reason, polyolefin resins have been actively developed as a material replacing plasticized PVC. For example, films using polyolefin resins such as polyethylene (PE), ethylene-vinyl acetate copolymer, and polybutadiene are manufactured. However, a film using such a resin does not have sufficient flexibility, deformation recovery, and stress relaxation characteristics required for the film.

Therefore, the packaged film is often peeled off immediately, the film is wrinkled, or the film is too stressed, which is not suitable for practical use.

As a method for imparting flexibility to a polyolefin resin, particularly a polypropylene resin, modification by crosslinking a mixture of an elastomer and polypropylene is widely used. For example, Japanese Patent Application Laid-Open No. 1-247441 discloses an elastomeric resin obtained by crosslinking an elastomer composed of ethylene-α-olefin and polypropylene in the presence of a crosslinking aid as an automobile part such as a bumper part.

The above-mentioned elastomeric crosslinked resins are excellent in strength and elasticity, but since they are post-blends, the elastomer component is not sufficiently dispersed in polypropylene, and in order to maintain good dispersibility, The molecular weight ranges of the elastomer and polypropylene that can be used are limited, and the resulting crosslinked resin is insufficient in flexibility and elongation. Furthermore, the above-mentioned crosslinked resin cannot satisfy applications other than injection molding.

As a polyolefin resin capable of forming a film, which is not used for injection molding, Japanese Patent Publication No. 59-501.
Japanese Unexamined Patent Publication No. 72 discloses a resin obtained by cross-linking an ethylene copolymer or crystalline polypropylene with a specific ethylene-acrylic polymer copolymer. These resins are ethylene-vinyl acetate copolymers, ethylene-acrylic acid ester copolymers, ethylene-methacrylic acid ester copolymers, ethylene-methacrylic acid copolymers, or ethylene-acrylic acid copolymers. Either is an essential ingredient. Since the above copolymer contains a copolymer component such as acrylic acid or vinyl acetate, the resin has insufficient heat resistance and flexibility, and a good film cannot be obtained.

In order to improve the flexibility of the polyolefin-based resin, a method of increasing the proportion of the elastomer component in the copolymer is generally used, but in the case of carrying out the above-mentioned crosslinking treatment, an extruder or the like is used. The cost is high because of the mechanical mixing operation. Furthermore, when the elastomer component has a high molecular weight, it aggregates and does not sufficiently disperse, so that the molecular weight of the elastomer component used is limited. For this reason,
The resin accompanied by the above mechanical mixing has insufficient physical properties such as flexibility and deformation recovery property, and it is the current situation that a good film cannot be obtained.

Elastomers obtained by copolymerizing various α-olefins with linear polyethylene (Japanese Patent Application Laid-Open No. 61-4463).
No. 5) and a styrene-containing conjugated diene elastomer (Japanese Patent Laid-Open No. 62-51440). However, even if these are used alone, heat resistance and stretchability cannot be obtained, and other It is necessary to laminate a resin, which is insufficient for film use.

[0010]

An object of the present invention is to provide a polyolefin resin composition capable of forming a film having excellent strength, deformation recovery and stress relaxation characteristics, and having flexibility, extensibility and heat resistance. It is to provide a film obtained by using this composition.

[0011]

The first polyolefin resin composition of the present invention is a polyolefin resin A50-
95% by weight and 50 to 5% by weight of a polyolefin resin B, the polyolefin resin A is a copolymer composed of the following components (i) and (ii): (i) propylene, and / or Or a combination of propylene and α-olefin; (ii) ethylene, and / or a combination of ethylene and α-olefin;
It is a polyolefin resin having a random branched molecular structure.

The second polyolefin resin composition of the present invention contains 50 to 95% by weight of the above-mentioned polyolefin resin A and 50 to 5% by weight of a polyethylene resin C, and the polyethylene resin C is a tetravalent transition. Polymerization is carried out using a metatheron compound containing a metal as a catalyst.

In a preferred embodiment, the polyolefin resin A is prepared by a multistage polymerization method in which the component (i) is first polymerized.

In a preferred embodiment, the test piece of the polyolefin resin B is subjected to a melt extension test at an extension strain rate in the range of 0.01 to 1.0 s ^-1 , and the extension strain amount a (0. 1 ≦ a ≦ 1.0) and b are 1:10, the respective melt extensional viscosities η _a and η _b satisfy the following relational expression (I).

[0015]

[Equation 2]

The polyolefin resin B does not contain a gel component.

In a preferred embodiment, the polyethylene resin C has a density of 0.860 to 0.950.
g / cm ³ , preferably 0.870 to 0.945 g / c
m ³ and measured by the cross fractionation method,
The range from the temperature at the time of 10% by weight elution to the temperature at the time of 100% by weight elution is within 30 ° C., preferably within 28 ° C., and the molecular weight distribution is 1.5-3.
5, preferably 1.7 to 3.0.

The film of the present invention is formed from the above-mentioned polyolefin resin composition.

The present invention will be described in detail below.

The polyolefin resin A used in the present invention comprises (i) propylene, and / or a combination of propylene and an α-olefin, and (ii) ethylene, and / or a combination of ethylene and an α-olefin. Is a copolymer of Therefore, the polyolefin resin A is a copolymer having propylene, ethylene, and optionally α-olefin as a component.
This resin A has a polypropylene block, a polyethylene block, an α-olefin block formed by bonding only a propylene component in the molecule, an ethylene-α-olefin block formed by bonding ethylene and an α-olefin, and the like. As the α-olefin component, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-
A penten or the like is used.

The block component which is present in the resin A of the present invention as (i) propylene and / or a combination of propylene and an α-olefin is, for example, a propylene homopolymer block, or propylene / ethylene, propylene / butene. -1, and propylene / 4-
A binary copolymer block such as methyl-1-pentene,
Alternatively, a terpolymer block such as propylene / ethylene / butene-1, and propylene / butene-1 / 4-methyl-1-pentene may be mentioned.

The block component which is present as (ii) ethylene and / or a combination of ethylene and α-olefin in the resin A is an ethylene homopolymer block or a copolymer block of ethylene and α-olefin. , For example ethylene / butene-1, ethylene /
Examples include hexene-1,4-methyl-1-pentene block.

The polyolefin resin A used in the present invention is produced, for example, by the following multistage polymerization method. First, as the first step, polymerization is carried out in the presence of a titanium compound catalyst and an aluminum compound catalyst, using the propylene monomer as the component (i) and, if necessary, the α-olefin monomer. Thereby, a propylene homopolymer, a propylene-α-olefin copolymer and the like are formed. Then, as a second step, a polyolefin resin is obtained by adding the component (ii) to a reaction liquid containing a titanium compound catalyst, for example, a reaction liquid containing the homopolymer or copolymer, and copolymerizing the mixture. A is obtained. At this time, the component (ii) may be added in one stage or in two stages. The polyolefin resin A obtained by this multi-step reaction can be a propylene-ethylene copolymer, a propylene-α-olefin copolymer, or a propylene-ethylene-α-olefin copolymer. Similarly, a multi-step copolymerization reaction can be performed depending on the purpose. The feature of this production method is that the polymerization is not completed in one step, but multi-step polymerization of two or more steps is performed. This allows multiple types of polymers to be built up in succession, forming copolymers such as intramolecular blends that are quite different from conventional mechanical blending polymer blends.

In the case of ordinary polymer blends, one method is to blend an elastomer component having a high molecular weight in order to improve flexibility and stretchability. However, in a usual polymer blend by mechanical mixing, a composition having a structure in which the elastomer component is finely dispersed cannot be obtained because the elastomer component having a high molecular weight has a high melt viscosity. Therefore, in contrast, in the case of the polyolefin resin A used in the present invention, the above component (ii) constitutes an elastomer component, that is, a relatively soft portion. This component (ii) has a high melt viscosity because of its high molecular weight, but by using the above-mentioned multistage polymerization method, the above components (i) and (ii), that is, a relatively hard portion and a relatively soft portion, can be obtained. It is possible to achieve a finely dispersed molecular structure.

Resins such as propylene and olefin block copolymers obtained by conventional polymerization methods are
Ethylene, α-olefin, etc. copolymerized as a flexibility-imparting component is limited to about 50 wt% with respect to polypropylene as the main component in the production process thereof, and the content is usually 30 wt%. Up to%. For this reason, it was very difficult for the block copolymer to realize flexibility like that of plasticized PVC. On the other hand, according to the above-mentioned multi-stage polymerization method, about 8
The content of 0 to 95% by weight can be contained, and a polyolefin-based resin having the same physical properties as plasticized PVC can be obtained.

As such a manufacturing method, for example, there is a method described in JP-A-4-224809. In this method, as a titanium compound, for example, titanium trichloride and magnesium chloride are co-ground, and this is orthotitanic acid n
A spherical solid titanium catalyst having an average particle diameter of 15 μm, which is obtained by treating with —butyl, 2-ethyl-1-hexanol, ethyl p-toluate, silicon tetrachloride, diisobutyl phthalate, or the like, is used. In this method, a silicon compound as an electron donor, especially diphenyldimethoxysilane, and ethyl iodide are further added to the polymerization tank. Further, JP-A-4-283252 discloses that a titanium compound obtained by treating an adduct of magnesium chloride and alcohol with titanium tetrachloride and an electron donor is used. Japanese Unexamined Patent Publication (Kokai) No. 4-266954 discloses a method using a catalyst containing a titanium compound having at least one halogen-titanium bond supported on an active magnesium dihalide and an electron donor compound. . In addition to these methods, for example, JP-A-4-96912, JP-A-4-96907, JP-A-3-174410, and JP-A-2-170803.
No. 2, 170, 802 and No. 3, 20543.
No. 9, JP-A-61-42553 and the like describe such a manufacturing method. When manufacturing the polyolefin resin A contained in the composition of the present invention, any known method as described above can be used.
Examples of commercially available resins obtained by such a production method include "PER" manufactured by Tokuyama Soda Co., Ltd. and "Cataloy" manufactured by Highmont Co., Ltd. Any of these can be used in the present invention.

Further, the above-mentioned polyolefin resin A is
Usually, the amount of components eluted at 90 ° C or higher in the cross fractionation method is 5
Is in the range of 50% by weight. When the amount of the eluted component is less than 5% by weight, the strength of a molded article using the obtained composition, for example, a film, is insufficient, and when the amount of the eluted component exceeds 50% by weight, whitening or necking occurs and the tensile properties are deteriorated. descend.

The polyolefin resin B used in the present invention has a random branched molecular structure. This molecular structure does not have a specific controlled structure, but has arbitrary branched portions. This resin B test piece was subjected to a melt extension test at an extension strain rate in the range of 0.01 to 1.0 s ⁻¹ , and the extension strain amounts a (0.1 ≦ a ≦ 1.0) and b at two points were measured. When it is 1:10, each melt extensional viscosity η _a and η _b satisfies the following relational expression (I).

[0029]

(Equation 3)

This melt extensional viscosity can be obtained, for example, by subjecting it to a melt extensional test using a melten rheometer (manufactured by Toyo Seiki Co., Ltd.). A specific test method will be shown in Examples described later, and the outline thereof is as follows. A cylindrical resin sample is pulled uniaxially at a temperature exceeding the melting point of the resin, and the tensile tension during melting is measured. Melt tension and melt viscosity are (melt viscosity) = (melt tension) / (strain rate)
Therefore, in the present invention, the melt tension is defined as melt extensional viscosity. In the case of a resin having a random branched molecular structure such as the polyolefin resin B of the present invention, this melt extensional viscosity increases at the time of large deformation. Therefore, as shown in the formula (I), the value of η _b / η _a is 3.0 to 1
It takes a large value of 00. This thickening at the time of large deformation is derived from the entanglement of the polyolefin resin B molecules.
The effect of the entanglement of the resin B is that the composition containing the resin B exhibits excellent elastic recovery during inflation molding. Therefore, the composition of the present invention exhibits excellent inflation molding stability, and is also excellent in foaming stability when a foam is obtained.

The polyolefin resin B preferably contains no gel component. The gel content is represented by the gel fraction as shown in the examples below. The gel fraction is indicated by the insoluble matter in xylene at high temperature. The polyolefin resin B of the present invention has a gel fraction of 0% obtained by this test and contains no gel fraction at all. By not including the gel component at all, the entanglement effect of the polyolefin resin B is increased. Therefore, a high-quality film can be easily obtained from the composition of the present invention containing the resin B by inflation molding, and the foaming stability is excellent even when a foam is obtained.

The polyolefin resin B may be either a polypropylene homopolymer, a copolymer containing propylene as a main component, or a mixture thereof. This copolymer can be obtained by copolymerization or graft polymerization. Examples of this copolymer include a polypropylene-α-olefin copolymer containing 85% by weight or more of a polypropylene portion. Examples of the α-olefin used as a component of the copolymer include ethylene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-butene, 1-pentene and the like.
A polyolefin resin having a random branched molecular structure can be commercially prepared by the method disclosed in JP-B-62-121704 or JP-B-2-298536. According to this preparation method, polypropylene is subjected to electron beam irradiation or peroxide treatment, whereby a random branched molecular structure is formed. In these inventions, a polyolefin resin having a randomly branched molecular structure is used for a coating material, a stretched film, and a blown film.

Polyethylene resin C used in the present invention
Is polymerized using a metallocene compound containing a tetravalent transition metal as a catalyst.

Examples of the tetravalent transition metal include titanium, zirconium, nickel, palladium, hafnium and platinum. A compound in which one or more cyclopentadienyl rings and their analogs are bound as ligands to these tetravalent transition metals is generally referred to as a metallocene compound.

The analogs of the above cyclopentadienyl ring include cyclopentadienyl ring substituted by a hydrocarbon group, a substituted hydrocarbon group or a hydrocarbon-substituted metalloid group, a cyclopentadienyl oligomer ring, an indenyl ring, And an indenyl ring substituted with a hydrocarbon group, a substituted hydrocarbon group or a hydrocarbon-substituted metalloid group. Examples of the ligand include monovalent anion ligands such as chlorine and bromine or divalent anion chelate ligands, hydrocarbons, alkoxides, aromatic or aliphatic amides, aromatic or aliphatic phosphides, and the like. Representative hydrocarbon groups are methyl, ethyl,
Propyl, butyl, amyl, isoamyl, hexyl, isobutyl, heptyl, octyl, nonyl, decyl, cetyl, 2-ethylhexyl, and phenyl.

Examples of the metallocene compound having the above ligand coordinated are cyclopentadienyl titanium tris (dimethylamide), methylcyclopentadienyl titanium tris (dimethylamide), bis (cyclopentadienyl) titanium dichloride, and dimethylsilyl tetra. Methylcyclopentadienyl-tert-butylamide zirconium dichloride, dimethylsilyltetramethylcyclopentadienyl-pn-butylphenylamide zirconium dichloride, methylphenylsilyltetramethylcyclopentadienyl-tert-butylamide hafnium dichloride, indide Nyltitanium tris (dimethylamide), indenyltitanium tris (diethylamide), indenyltitanium tris (di-n-propylamide), Down de nil titanium bis (di -n-
Propylamide) and the like.

Polymerization of the polyethylene resin C is usually carried out in a catalyst system in which methylaluminoxane (MAO) as a cocatalyst, a boron compound and the like are added to the metallocene compound. The ratio of the cocatalyst used to the metallocene compound is 10 to 1,000,000 mol times, preferably 50 to 5,000 mol times. For the polymerization method,
There is no particular limitation, and a solution polymerization method using an inert medium, a bulk polymerization method in which an inert medium does not substantially exist, a gas phase polymerization method, or the like can be used. The polymerization temperature is -100.
℃ ~ 300 ℃, as the polymerization pressure, atmospheric pressure ~ 100kg /
It is common to carry out in cm ² . In this polymerization reaction, since the reaction active points are uniform, a resin having a similar molecular weight and a similar degree of branching can be obtained, and a resin having no variation in crystallinity can be obtained. Furthermore, in this reaction, during the copolymerization, the copolymerization components are introduced in a homogeneous dispersion state,
Effective branched molecules can be generated. Therefore, the polyethylene resin C obtained by this reaction has a narrow molecular weight distribution, and the copolymerization component is uniformly introduced into each molecule. As a result, an effective tie chain (a molecule that connects the crystalline portion and the amorphous portion) is generated, and thus the surface impact property is dramatically improved. Further, since the molecular weight distribution is narrow and no low molecular weight component is contained, a low crystalline polyethylene free from stickiness can be obtained. As such a polyethylene resin C, CGCT of Dow Chemical Co., EXACT of Exxon Chemical Co., etc. are commercially available. On the other hand, in the case of normal Ziegler-Natta catalyst polymerization,
In the copolymer of ethylene and α-olefin, α-
Olefin is abundantly present in the low molecular weight one of the obtained copolymers, and almost absent in the high molecular weight component. As a result, highly crystalline component (relatively hard part)
And a component with low crystallinity (relatively soft portion) are mixed in the resin. Therefore, the distance between crystals becomes non-uniform,
It prevents the creation of effective tie chains. In addition, since the molecular weight distribution and the copolymerization component distribution are wide, low crystalline polyethylene (polyethylene with a large amount of copolymerization components) causes problems such as stickiness and odor due to the influence of the low molecular weight component, which is a problem in actual use. There are many.

The polyethylene resin C has a density of 0.8.
60 to 0.950 g / cm ³ , preferably 0.870 to
It is 0.945 g / cm ³ . Furthermore, the range from the temperature at the time of 10% by weight elution to the temperature at the time of 100% by weight elution being measured by the cross fractionation method is 30.
Within ° C, preferably within 28 ° C, and the molecular weight distribution is 1.5-3.5, preferably 1.7-3.0. If the density is less than 0.860 g / cm ³ , the crystallinity of the resin will be low and the heat resistance of the resulting resin composition will be low. When the density exceeds 0.950 g / cm ³ , the crystallinity becomes high and the dispersed state deteriorates, so that the stress relaxation property of the obtained resin composition deteriorates. The temperature range is 30 ℃
When it exceeds, the high crystallinity portion and the low crystallinity portion are present in the resin C at the same time, and the stress relaxation property of the obtained resin composition is deteriorated. The above molecular weight distribution is 1.
When it is less than 5, the dispersion state of the relatively hard portion and the relatively soft portion in the obtained resin composition becomes poor,
Tensile properties deteriorate. When the molecular weight distribution is more than 3.5, the abundance ratio of the molecules having too low a molecular weight and the molecules having too high a molecular weight becomes high, and the stress relaxation property deteriorates.

In the present invention, depending on the purpose, other thermoplastic resins such as low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, ethylene Propylene rubber, polyvinyl acetate, polybutene and the like may be mixed in a proportion of 0 to 20% by weight.

The above cross fractionation method can be appropriately used for the characterization of the above resins A to C. This cross fractionation method is (1) temperature rising elution fractionation (TREF) for measuring the crystallinity distribution of polyethylene resin C by the following method.
= Temperature Rising Elution Fractionation), and (2) measurement of molecular weight and molecular weight distribution by high temperature GPC. This cross-fractionation method includes, for example, the TREF device and high temperature GPC (ie, SEC =
Cross-fractionation chromatograph (CFC-T150A) equipped with Size Exclution Chromatograph)
Type: manufactured by Mitsubishi Petrochemical Co., Ltd. can be used.

The resin composition of the present invention may contain an antioxidant, a stabilizer, a pigment, an antifogging agent, an antistatic agent, a flame retardant and the like depending on its purpose. Antioxidants and stabilizers include commercially available phenolic antioxidants, phosphorus antioxidants,
Compounds that prevent oxidative degradation of macromolecules such as amine-based antioxidants, sulfur-based antioxidants, etc. may be used, and these may be used alone or in combination. Further, if necessary, fillers such as carbon black, clay, talc, calcium carbonate, alumina, silica, kaolin, graphite and glass fiber can be used. The mixing can be carried out by known mechanical melt mixing such as extruders, Banbury mixers, rolls, Brabender plastographs, kneaders and the like.

The film of the present invention can be produced by inflation molding or T-die molding of the above resin composition. A single or a plurality of extruders can be used for the above-mentioned molding, and a method such as single extrusion, coextrusion or extrusion laminating can be used.

The film thus obtained is excellent in strength, deformation recovery and stress relaxation characteristics, and has flexibility and
Excellent extensibility and heat resistance.

This polyolefin-based film may be used alone or laminated with another resin as long as it does not impair the effects of the present invention.

[0045]

[Function] Polyolefin resin A used in the present invention
Can be obtained by copolymerizing polypropylene, which constitutes a relatively hard portion, with ethylene and / or α-olefin, which constitutes a relatively soft portion, as described above, preferably by multistage polymerization. Therefore,
Unlike the conventional polypropylene / elastomer blend, that is, a blend involving mechanical mixing, the polyolefin-based resin A is an ethylene-
Since the α-olefin copolymerized portion is compatible with each other at the molecular level, the polyolefin-based resin A achieves a uniform and very fine dispersion state.

In the polyolefin resin B having a randomly branched molecular structure used in the present invention, most of its molecular chain exists as an amorphous portion, that is, a soft portion. Due to the effect of the entanglement of the soft branched molecular chains, the melt elongation viscosity of the polyolefin resin B at the time of large deformation is remarkably increased as compared with the polypropylene resin generally widely used from the past.

Generally, when a polyolefin resin and the above polyolefin resin B are mixed, the soft branched molecular chain of the resin B is compatible with the amorphous portion in the above polyolefin resin. As a result, it is presumed that the effect of entanglement of molecular chains in the resin composition is increased and the strength and the deformation recovery property are improved.

When a resin such as the polyolefin resin A of the present invention having a uniform and extremely fine amorphous portion dispersion state is mixed with the polyolefin resin B, the soft branched molecular chains of the resin B become molecules. It is presumed that it is compatible with the amorphous part of resin A, which is in a finely dispersed state at a level, and the entanglement of molecular chains occurs in a very finely dispersed state, and the effect of the entanglement remarkably increases, so that the strength and the deformation recovery property are significantly improved. To be done.

Polyethylene resin C used in the present invention
In the polymerization reaction using the metallocene catalyst for preparing the above, since the reaction active sites are uniform, a resin having a similar molecular weight and a similar degree of branching is obtained, and a resin having no variation in crystallinity is obtained. In addition, the reaction produces significant amounts of long branching moieties. Therefore, it is considered that the resin C has a random branched molecular structure like the resin B.

When a resin such as a polyolefin resin A having a uniform and very fine amorphous portion dispersion state is mixed with such a polyethylene resin C, the long branched portion of the resin C is at a molecular level. Since it is compatible with the amorphous part of resin A, which is in a finely dispersed state, it is assumed that the entanglement of molecular chains occurs uniformly without changing the very finely dispersed state, maintaining flexibility and improving the stress relaxation property. To be done.

Therefore, the polyolefin resin compositions A / B and A / C of the present invention and the films obtained from the above resin compositions are excellent in strength, deformation recovery property and stress relaxation property, and have flexibility and extensibility. , And heat resistance.

[0052]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. The evaluation items in the examples of the present invention are as follows.

Cross fractionation method A cross fractionation chromatograph device (CFC-150) equipped with a TREF device and a high temperature GPC device as a system.
A-type: manufactured by Mitsubishi Petrochemical Co., Ltd.) was used to measure the polyolefin resin. As the TREF method, first, a polyethylene resin is dissolved in o-dichlorobenzene at 140 ° C. or a temperature at which the resin is completely dissolved. Next, this solution was cooled at a constant temperature to form a thin polymer layer on the surface of an inert carrier prepared in advance. Next, the temperature was raised continuously or stepwise, and the concentrations of the eluted components were measured in each predetermined temperature range. The difference in crystallinity of the molecule can be measured by measuring the component concentration in the above predetermined temperature range. That is, a component that elutes at a low temperature has low crystallinity, and a component that elutes at a high temperature has high crystallinity.

Structure of polypropylene by infrared analysis (FT-IR) The components eluted at 90 ° C. or higher in the above cross fractionation method were collected. This component is high in polypropylene. Infrared absorption spectrophotometer (SYSTE
Infrared absorption spectrum was measured using M 200FT-IR: Perkin Elmer Japan KK, 720c.
The peak around m ^{-1 to} around 730 cm ^-1 was examined, and resin A
The structure of polypropylene present as a component of was investigated.

Tensile test Using a tensile tester (Tensilon UST-500: manufactured by Orientec Co., Ltd.), the initial length (grabbing interval) of a sheet sample having a width of 3 mm was set to 10 mm and a pulling speed of 200 was set.
The rupture stress when pulled at mm / min was measured.

Stress relaxation test Using a tensile tester (Autograph AG-500B: manufactured by Shimadzu Corporation), the initial length (grabbing interval) of a sheet sample having a width of 3 mm was set to 10 mm, and the pulling speed was 500 m.
It was pulled at a rate of m / min and kept in that state for 5 minutes at a predetermined elongation (25%). The change with time of the tensile strength when held was measured, and the stress residual rate was measured by the following formula.

Residual stress rate X = (tensile strength after 5 minutes / initial tensile strength) × 100 (%) Measurement of gel fraction 1 g of a sample was immersed in about 50 ml of xylene and dissolved at 120 ° C. for 24 hours. The insoluble matter was filtered through a 200-mesh wire net, the dry weight of the obtained insoluble matter was measured, and the gel fraction was determined by the following formula.

Gel fraction = (weight of insoluble matter / weight of initial sheet) × 100 (%) The characteristics of the polyolefin resins A and B used in the following Examples 1 to 6 and Comparative Examples 1 to 5 are shown in Table 1 and 2 shows. Table 1 shows the cross fractionation method and the FT-I.
3 shows the structure of polypropylene in the polyolefin resin A by R. Table 2 shows the melt elongation characteristics and the gel fraction of the polyolefin resin B.

[0059]

[Table 1]

[0060]

[Table 2]

Example 1 Resin A is shown in Table 3 against Resin A.
A predetermined amount shown in (1) and (2) were melted and kneaded at 170 ° C. by a Brabender plastograph to obtain a resin composition. The unit of the mixing ratio in Table 3 is% by weight. This resin composition was press molded into a 0.4 mm sheet at 170 ° C. A test sample having a width of 3 mm was prepared from this sheet and subjected to the tensile test and the stress relaxation test.

70% by weight of Resin A (PO-2), Resin B
Table 3 shows the test results of the resin composition obtained by mixing 30% by weight of (HMS-2). The results of Examples 2 to 6 and Comparative Examples 1 to 5 described later are also shown in Table 3.

[0063]

[Table 3]

(Examples 2 to 6) The same procedure as in Example 1 was carried out except that the types of resin A and resin B and their mixing ratios were changed as shown in Table 3.

Comparative Examples 1 to 3 Molding and testing were carried out in the same manner as in Example 1 using only the resin A shown in Table 3.

Comparative Examples 4 to 5 Using Resin A and Resin B shown in Table 3, molding and testing were carried out in the same manner as in Example 1.

The following Examples 7-12 and Comparative Examples 6-1
The properties of the polyolefin resin A and the polyethylene resin C used in No. 1 are shown in Table 1 above and Table 4 below. Table 4 shows the temperature range, the molecular weight distribution, and the density of the polyethylene resin C in the cross fractionation method.

[0068]

[Table 4]

(Example 7) For resin A, resin C is shown in Table 5.
A predetermined amount shown in (1) and (2) were melted and kneaded at 170 ° C. by a Brabender plastograph to obtain a resin composition. The unit of the mixing ratio in Table 5 is% by weight. This resin composition was press molded into a 0.4 mm sheet at 170 ° C. A test sample having a width of 3 mm was prepared from this sheet and subjected to the tensile test and the stress relaxation test.

Resin A (PO-2) 60% by weight, Resin C
Table 5 shows the test results for the resin composition in which 40% by weight of (metallocene PE-2) was mixed. Example 8 described later
Table 12 also shows the results of ˜12 and Comparative Examples 6 to 11.

[0071]

[Table 5]

(Examples 8 to 10) The same procedure as in Example 7 was carried out except that the kinds of the resin A and the resin C and the mixing ratio thereof were changed as shown in Table 5.

Comparative Examples 6 to 8 Using only the resin A shown in Table 5, molding and testing were carried out in the same manner as in Example 7.

Comparative Examples 9 to 10 Using Resin A and Resin B shown in Table 5, molding and testing were carried out in the same manner as in Example 7.

Comparative Example 11 Using resin A shown in Table 5 and ordinary low density polyethylene, molding and testing were carried out in the same manner as in Example 7.

As described above, it can be seen from the above-mentioned examples that a film having improved fracture stress and residual stress relaxation rate can be obtained. According to the present invention, it is possible to obtain a film which is excellent in strength, deformation recovery property and stress relaxation property and is excellent in flexibility, extensibility and heat resistance.

[0077]

According to the present invention, as described above, a polyolefin resin composition capable of preparing a film having excellent strength, deformation recovery property, and stress relaxation property, and having excellent flexibility, extensibility, and heat resistance. Is obtained. The obtained film is a film for stretch packaging, a surface protective film, a stretch film for grass, a stretch film for agriculture,
It can be applied to heat-shrinkable films, adhesive plaster films, shrink films, etc., and can be widely used as a plasticized PVC substitute film.

Claims (6)

[Claims] 1. A polyolefin resin composition containing 50 to 95% by weight of a polyolefin resin A and 50 to 5% by weight of a polyolefin resin B, wherein the polyolefin resin A comprises the following components (i) and ( A copolymer comprising ii): (i) propylene, and / or a combination of propylene and an α-olefin; (ii) ethylene, and / or a combination of ethylene and an α-olefin; the polyolefin resin B. Is a polyolefin resin having a random branched molecular structure. 2. A polyolefin resin composition containing 50 to 95% by weight of a polyolefin resin A and 50 to 5% by weight of a polyethylene resin C, wherein the polyolefin resin composition A comprises the following component (i): And (ii) a copolymer comprising: (i) propylene, and / or a combination of propylene and an α-olefin; (ii) ethylene, and / or a combination of ethylene and an α-olefin; Resin C is a polyolefin-based resin composition obtained by a polymerization reaction using a metallocene compound containing a tetravalent transition metal as a catalyst. 3. The polyolefin resin composition according to claim 1, wherein the polyolefin resin A is prepared by a multistage polymerization method in which the component (i) is first polymerized. 4. A test piece of the polyolefin resin B
0.01-1.0s ^-1Melt at elongation strain rates in the range of
Subjected to an extension test, the extension strain amount a (0.1 ≦
a ≦ 1.0) and b are 1:10,
Melt elongation viscosity η_aAnd η_bSatisfies the following relational expression (I):The polyolefin resin B does not contain a gel component.
The polyolefin resin group according to claim 1 or 3.
Adult. 5. The polyethylene-based resin C has a density of 0.860 to 0.950 g / cm ³ , and a temperature at which 10 wt% elution is completed to 100 wt% elution is completed by a cross fractionation method. Is within 30 ° C. and the molecular weight distribution is from 1.5 to 3.5
The polyolefin resin composition according to claim 2 or 3. 6. A film molded from the polyolefin resin composition according to claim 1.