JPH0994933A - Stretch film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stretch film excellent in mechanical strength such as self-adhesiveness, tear propagation resistance, thrust strength, breaking strength, breaking elongation, transparency, stretchability or bundling properties. SOLUTION: A stretch film is obtained by laminating a layer composed of an ethylene/α-olefin copolymer and an ethylene/α-olefin copolymer with density of 0.86-0.94g/cm<3> or an ethylene (co)polymer by high pressure radical polymerization by a Ziegler catalyst.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a stretch film, and more specifically, to mechanical strength such as self-adhesiveness, tear propagation resistance, puncture strength, breaking strength and breaking elongation,
It is intended to provide a stretch film having a laminated structure which is excellent in transparency, stretchability and binding property.

[0002]

2. Description of the Related Art In recent years, pallet stretch packaging, in which a film is stretched and wrapped around a unitized cargo on a pallet, is wrapped in the industry as an energy-saving packaging method. The pallet stretch wrapping film used for these has self-adhesiveness,
It is required that the stretch ratio be large and the strength against the protrusions be strong without causing uneven stretching or stretch breakage during stretch packaging.

Conventionally, polyethylene resins, ethylene / vinyl acetate copolymer resins, polyvinyl chloride resins and the like have been generally used as these pallet stretch films. Recently, in addition to polyethylene resin and ethylene vinyl acetate copolymer resin, mechanical strength,
Due to its excellent transparency, stretchability and adhesiveness, ethylene
Linear low-density polyethylene (LLDPE) consisting of an α-olefin copolymer, alone or in a mixture with an ethylene / vinyl acetate copolymer, a laminate (Japanese Patent Publication No. 2-18983).
No. 56-74737, etc.) are rapidly becoming widespread.

[0004] As another application, the pasture grass compacted in a roll form is wrapped in a stretch film and fermented to prepare a feed. Stretch film for grass is required to maintain high airtightness for a long time outdoors, so toughness that does not break due to the protrusions of the grass surface that has been compacted, sufficient stretchability, cohesiveness, elasticity, self-adhesiveness, etc. The same properties as stretch films are required. Recently, from the viewpoint of labor saving of the stretch film, simplification of workability, etc., a higher film is required, and in particular, the performance of the LLDPE film, that is, self-adhesiveness, tear propagation resistance, puncture strength,
It is desired to further improve mechanical strength such as breaking strength and breaking elongation, transparency, stretchability, and binding property.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made as a result of extensive studies in view of the above problems, and has a density satisfying specific conditions of 0.86 to 0.94 g / cm ³ and a melt flow rate. (MFR) 0.1-50 g / 10 min (A) Laminate including (I) I-layer containing ethylene / α-olefin copolymer and (B) other II-layer consisting of ethylene-based copolymer Mechanical strength such as self-adhesiveness, tear propagation resistance, puncture strength, breaking strength, breaking elongation, etc.
It is intended to provide a stretch film excellent in transparency, stretchability, binding property and the like.

[0006]

According to the present invention, (a) density is 0.86 to 0.94 g / cm ³ , (a) melt flow rate (MFR) 0.1 to 50 g / 10 minutes, (c) Molecular weight distribution (Mw / Mn) is 1.8 to 3.5, (d) Composition distribution parameter Cb is 1.10 to 2.00, (e) 25 ° C.
The amount X (wt%) of ortho-dichlorobenzene (ODCB) -soluble component and density d and MFR (melt flow rate) satisfy the following relationship: a) Density d and MFR values are d-0.008logM
In the case of FR ≧ 0.93 X <2.0 b) The value of the density d and MFR is d−0.008logM
When FR <0.93 X <9.8 × 10 ³ (0.9300-d + 0.008l)
ogMFR) ² +2.0 (f) There are multiple peaks of the elution temperature-elution amount curve by the continuous temperature rising elution fractionation method (TREF). Ethylene / α-olefin copolymerization satisfying the above (a) to (f) The first layer composed of the united product, (B1) an ethylene-α-olefin copolymer having a density of 0.86 to 0.94 g / cm ³ using a Ziegler type catalyst, and (B2) an ethylene (co) polymer using high pressure radical polymerization. 1. A stretch film comprising a laminate containing at least one (B) ethylene-based polymer (II) layer, or both surfaces of the first layer (B1) having a density of 0.
86 to 0.94 g / cm ³ of ethylene-α-olefin copolymer, (B2) at least one kind of ethylene (co) polymer by high-pressure radical polymerization (B) a second layer comprising an ethylene-based polymer; The present invention provides a stretch film having a laminated resistance provided with a third layer.

Another aspect of the present invention is to provide a resin or a resin composition 10 which constitutes the I-th layer, the II-th layer and / or the III-layer according to the above-mentioned claims 1 to 3 having improved adhesiveness.
Provided is a stretch film in which 0 to 20 parts by weight of a tackifier is blended.

Hereinafter, the present invention will be described in detail. Ethylene / α-satisfying the following (a) to (f) used in the present invention:
The olefin copolymer is a copolymer of ethylene and one or more kinds selected from α-olefins having 3 to 20 carbon atoms. The α-olefin having 3 to 20 carbon atoms is preferably one having 3 to 12 carbon atoms, and specifically, propylene, 1-butene, 4-methyl-1-pentene, 1-
Hexene, 1-octene, 1-decene, 1-dodecene,
And the like. Further, it is desirable that the total content of these α-olefins is selected in the range of usually 30 mol% or less, preferably 20 mol%.

[A to K] (a) Density is 0.86 to 0.94 g / cm ³ (a) Melt flow rate (MFR) 0.1 to 50 g /
10 minutes (c) Molecular weight distribution (Mw / Mn) is 1.8 to 3.5 (d) Composition distribution parameter Cb is 1.10 to 2.00 (e) Ortho-dichlorobenzene (ODC) at 25 ° C.
B) The amount X (wt%) of the soluble component and the density d and MFR (melt flow rate) satisfy the following relationship: a) The values of the density d and MFR are d-0.008logM
In the case of FR ≧ 0.93 X <2.0 b) The value of the density d and MFR is d−0.008logM
When FR <0.93 X <9.8 × 10 ³ (0.9300-d + 0.008l)
(ogMFR) ² +2.0 (f) There are multiple peaks in the elution temperature-elution amount curve by the continuous temperature rising elution fractionation method (TREF).

The (A) density of the ethylene / α-olefin copolymer (A) of the present invention is 0.86 to 0.94 g / cm 3.
^3, preferably in the range of 0.88~0.93g / cm ^3, more preferably 0.89~0.925g / cm ^3. If the density is less than 0.86 g / cm ³ , there is a risk of difficulty in stretchability and binding property, and if it exceeds 0.94 g / cm ³ , there is a problem in tackiness.

The (A) MFR of the ethylene / α-olefin copolymer (A) of the present invention is 0.1 to 50 g / 10 minutes,
It is preferably 0.2 to 30 g / 10 minutes, more preferably 0.3 to 20 g / 10 minutes. MFR is 0.1g / 1
If it is less than 0 minutes, the moldability will be poor, and if it exceeds 50 g / 10 minutes, the mechanical strength and the binding property will be poor.

The Mw / Mn of the ethylene / α-olefin copolymer (C) of the present invention (C) is 1.8 to 3.5,
It is preferably 2.0 to 3.0, more preferably 2.2.
It is desirable to be in the range of 2.8. Mw / Mn is 1.
If it is less than 8, the moldability is poor, and if it exceeds 3.5, the impact resistance is poor. The molecular weight distribution (Mw / Mn) is calculated by gel permeation chromatography (GP).
C), the weight average molecular weight (Mw) and the number average molecular weight (M
n) is obtained and this ratio Mw / Mn is obtained.

The (A) composition distribution parameter Cb of the ethylene / α-olefin copolymer (A) of the present invention is 1.10.
˜2.00, preferably 1.12 to 1.70, and more preferably 1.15 to 1.50. If it is larger than 2.00, blocking tends to occur, the heat sealing property becomes poor, and a low molecular weight or high branching component often oozes out onto the resin surface, resulting in a hygienic problem.

The method for measuring the composition distribution parameter Cb of the ethylene / α-olefin copolymer is as follows. That is, ortho-dichlorobenzene (OD
135 ° C. so that the sample concentration becomes 0.2% by weight in CB)
Heat to dissolve. This solution was treated with diatomaceous earth (Celite 54).
The sample is transferred to a column packed with 5), cooled to 25 ° C. at a rate of 0.1 ° C./min, and the sample is deposited on the celite surface. Next, while flowing ODCB through the column at a constant flow rate, the temperature of the column is increased stepwise to 120 ° C. in steps of 5 ° C. to elute and separate the sample. Methanol is mixed with the eluate, the sample is reprecipitated, filtered and dried to obtain a fraction sample at each elution temperature. The weight fraction of the eluted sample at each temperature and the degree of branching (the number of branches per 1000 carbon atoms) are measured by 13 C-NMR.

For the fraction from 30 ° C. to 90 ° C., the branching degree is corrected as follows. That is, the measured branching degree is plotted against the elution temperature, and the correlation is approximated to a straight line by the method of least squares to create a calibration curve. The correlation coefficient of this approximation is large enough. The value obtained from this calibration curve is defined as the degree of branching of each fraction. The elution temperature is 95 ° C
For these components, a linear relationship is not always established between the elution temperature and the degree of branching, so this correction is not performed and measured values are used.

Next, the weight fraction w of each fraction
The i, the amount of change in the degree of branching _{b i} per the elution temperature 5 ° C. _{(b i}
-Bi _-1 ) to obtain the relative concentration c _i , and plot the relative concentration against the branching degree to obtain a composition distribution curve. This composition distribution curve is divided with a constant width, and the composition distribution parameter Cb is calculated from the following equation.

[0017]

[Equation 1]

Here, c _j and b _j are the relative density and branching degree of the j-th section, respectively. Composition distribution parameter Cb
Is 1.0 when the composition of the sample is uniform, and the value increases as the composition distribution spreads.

Many proposals have been made for a method of describing the composition distribution of an ethylene / α-olefin copolymer. For example, in JP-A-60-88016, numerical processing is performed assuming that the cumulative weight fraction has a specific distribution (lognormal distribution) with respect to the number of branches of each fractionated sample obtained by solvent fractionation of the sample. , Weight average branching degree (Cw) and number average branching degree (C
n) is calculated. This approximation calculation becomes less accurate when the number of branches of the sample and the cumulative weight fraction deviate from the lognormal distribution, and the correlation coefficient R is obtained when measurement is performed on commercially available LLDPE.
² is quite low and the accuracy of the value is not sufficient. Also, this C
The method of measuring w / Cn and the method of numerical processing are different from those of Cb of the present invention, but if the values are compared, Cw /
The value of Cn is considerably larger than that of Cb.

The amount of the ODCB-soluble component at 25 ° C. (e) of the ethylene / α-olefin copolymer of the present invention is measured by the following method. 0.5 g sample to 20 ml OD
After heating at 135 ° C. for 2 hours in CB to completely dissolve the sample, cool to 25 ° C. After leaving this solution at 25 ° C. overnight, the filtrate is collected by filtering through a Teflon filter. Wavenumber 292 of asymmetric stretching vibration of methylene in this filtrate
The absorption peak area near 5 cm ⁻¹ is obtained, and the sample concentration is calculated from the calibration curve prepared in advance. From this value,
Determine the ODCB soluble content at 25 ° C.

The relationship between (d) the amount of ODCB-soluble matter at 25 ° C., X wt% and the density d and MFR of the present invention is d
And the value of MFR satisfies d-0.008logMFR ≧ 0.93, X is less than 2% by weight, preferably less than 1% by weight. When d-0.008logMFR <0.93, X <9.8 ×. 10 ³ × (0.9300-d + 0.008
logMFR) ² +2.0 Preferably, X <7.4 × 10 ³ × (0.9300−d + 0.008)
logMFR) ² +1.0 More preferably, X <5.6 × 10 ³ × (0.9300−d + 0.008)
It is necessary to satisfy the relation of (logMFR) ² +0.5.

The ODCB-soluble component at 25 ° C. is a highly branched component and a low molecular weight component contained in the ethylene / α-olefin copolymer, which causes problems of hygiene and blocking of the inner surface of the molded product. It is desirable that the content is small. The amount of ODCB solubles is affected by the comonomer content and molecular weight. Therefore, the fact that the density and the amounts of MFR and ODCB-soluble component, which are indicators, satisfy the above relationship indicates that the uneven distribution of α-olefin contained in the whole copolymer is small.

The ethylene / α-olefin copolymer (A) of the present invention may have a plurality of peaks in the elution temperature-elution amount curve (f) determined by the continuous temperature rising elution fractionation method (TREF). is necessary. Further, it is particularly preferable that a peak exists between 85 ° C and 100 ° C. The presence of this peak improves the heat resistance of the molded body. FIG. 1 shows the elution temperature-elution amount curve of the copolymer of the present invention, and FIG. 2 shows the difference from the so-called metallocene-catalyzed copolymer.

The TREF measuring method according to the present invention is as follows. The sample is heated and dissolved at 135 ° C. in ODCB containing an antioxidant so that the sample concentration becomes 0.05% by weight. 5 ml of this sample solution was injected into a column filled with glass beads, and the column was cooled at a cooling rate of 0.1 ° C / min to 25
Cool down to ° C. and deposit the sample on the surface of the glass beads. Next, the sample is sequentially eluted while the column temperature is raised at a constant rate of 50 ° C./hr while flowing ODCB through the column at a constant flow rate. At this time, the concentration of the sample eluted in the solvent was 2925 cm of wave number of asymmetric stretching vibration of methylene.
^The absorption for ^-1 is continuously detected by an infrared detector.
From this value, the concentration of the ethylene / α-olefin copolymer in the solution is quantitatively analyzed to determine the relationship between the elution temperature and the elution rate. Since the TREF analysis can analyze the change of the elution rate with respect to the temperature change continuously with a very small amount of sample, it is possible to detect relatively fine peaks that cannot be detected by the fractionation method.

In the production of the specific ethylene / α-olefin copolymer of the present invention, it is desirable to polymerize with a catalyst composed of the following C1 to C5. That is, C1: a compound represented by the general formula Me ¹ R ¹ _p (OR ² ) _q X ¹ _4-pq (wherein Me ¹ represents zirconium, titanium, and hafnium, and R ¹ and R ² are each carbon. A hydrocarbon group of the formulas 1 to 24, X ¹ represents a halogen atom, p and q are integers satisfying the ranges of 0 ≦ p <4 and 0 ≦ p + q ≦ 4), and C2: general formula Me ² R ³ _m (OR ⁴ ) _n X ²
A compound represented by _z-mn (wherein Me ² is an element of Group I to III of the periodic table, R ³ and R ⁴ are each a carbon number of 1 to 2).
4 is a hydrocarbon group, X ² is a halogen atom or a hydrogen atom (however, when X ² is a hydrogen atom, Me ² is limited to a group III element of the periodic table), and z is a valence of Me ² . And m and n are integers satisfying the ranges of 0 ≦ m ≦ z and 0 ≦ n ≦ z, respectively, and 0 ≦ m + n ≦ z), C3: an organic cyclic compound having a conjugated double bond, And C4: a modified organoaluminum compound containing an Al—O—Al bond obtained by the reaction of an organoaluminum compound and water, and C5: a catalyst obtained by bringing an inorganic carrier and / or a particulate polymer carrier into contact with each other.

The above-mentioned catalyst component C1 has the general formula Me ¹ R
¹ _p wherein Me ¹ of _{^{(OR 2) q X 1 4}} -p-q compounds represented by represents zirconium, titanium, hafnium.
The type of these transition metals is not limited, and a plurality of transition metals can be used. However, it is particularly preferable that zirconium having excellent weather resistance of the copolymer is contained. R ¹ and R ² are each a hydrocarbon group having 1 to 24 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, and specifically, methyl group, ethyl group, propyl group, isopropyl group. , Alkyl groups such as butyl group; alkenyl groups such as vinyl group and allyl group; aryl groups such as phenyl group, tolyl group, xylyl group, mesityl group, indenyl group, naphthyl group; benzyl group, trityl group, phenethyl group, styryl group Group, benzhydryl group, phenylbutyl group, aralkyl group such as neophyl group, and the like. These may have branches. X ¹ represents a halogen atom such as fluorine, iodine, chlorine and bromine, and p and q satisfy the ranges of 0 ≦ p <4, 0 ≦ q <4, 0 ≦ p + q ≦ 4, and preferably 0 ≦ p + q ≦ The range is 4.

Examples of the compound represented by the above general formula of the catalyst component C1 include tetramethylzirconium, tetraethylzirconium, tetrabenzylzirconium, tetrapropoxyzirconium, tripropoxymonochlorozirconium, tetrabutoxyzirconium, tetrabutoxytitanium and tetrabutoxyhafnium. Examples thereof include Zr (OR) ₄ compounds such as tetrapropoxyzirconium and tetrabutoxyzirconium, and two or more kinds of these may be mixed and used.

The above catalyst component C2 has the general formula Me ² R.
^In the formula of the compound represented by ³ _m (OR ⁴ ) _n X ² _z-mn , Me ² represents a Group I to III element of the periodic table, and lithium, sodium, potassium, magnesium, calcium, zinc, boron. , Aluminum, etc. R ³ and R ⁴ are each a hydrocarbon group having 1 to 24 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, and specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, or a butyl group. An alkyl group such as a group; an alkenyl group such as a vinyl group and an allyl group; an aryl group such as a phenyl group, a tolyl group, a xylyl group, a mesityl group, an indenyl group and a naphthyl group; a benzyl group, a trityl group, a phenethyl group, a styryl group, Examples thereof include aralkyl groups such as a benzhydryl group, a phenylbutyl group and a neophyl group. These may have branches. X ² represents a halogen atom such as fluorine, iodine, chlorine and bromine, or a hydrogen atom. However, when X ² is a hydrogen atom, Me ² is limited to a group III element of the periodic table exemplified by boron, aluminum and the like. Further, z represents the valence of Me ² , m and n are integers satisfying the ranges of 0 ≦ m ≦ z and 0 ≦ n ≦ z, and 0 ≦ m + n ≦ z.

Examples of the compound represented by the above general formula of the catalyst component C2 include organolithium compounds such as methyllithium and ethyllithium; organomagnesium compounds such as dimethylmagnesium, diethylmagnesium, methylmagnesium chloride and ethylmagnesium chloride; dimethyl. Organozinc compounds such as zinc and diethylzinc; Organoboron compounds such as trimethylboron and triethylboron; Trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, tridecylaluminum, diethylaluminum chloride, ethylaluminum dichloride, ethylaluminum sesqui Organic aldehydes such as chloride, diethyl aluminum ethoxide, and diethyl aluminum hydride Derivatives such as iodonium compounds.

The above-mentioned organic cyclic compound having a conjugated double bond of the catalyst component C3 is a ring having two or more conjugated double bonds, preferably 2 to 4 and more preferably 2 to 3 conjugated double bonds. Or a cyclic hydrocarbon compound having 2 or more and having a total carbon number of 4 to 24, preferably 4 to 12; the cyclic hydrocarbon compound is partially 1 to 6 hydrocarbon residues (typically, A cyclic hydrocarbon compound substituted with an alkyl group having 1 to 12 carbon atoms or an aralkyl group); 2 or more, preferably 2 to 4, and more preferably 2 to conjugated double bonds.
One or more rings having three rings and a total carbon number of 4
An organosilicon compound having a cyclic hydrocarbon group of from 24 to 24, preferably 4 to 12; said cyclic hydrocarbon group being partially substituted by 1 to 6 hydrocarbon residues or an alkali metal salt (sodium or lithium salt) Organosilicon compounds. Particularly preferably, those having a cyclopentadiene structure in any of the molecules are desirable.

Examples of the preferred compounds include cyclopentadiene, indene, azulene and their alkyl, aryl, aralkyl, alkoxy or aryloxy derivatives. Moreover, the compound which these compounds couple | bonded (bridge | crosslink) through the alkylene group (The carbon number is 2-8 normally, Preferably 2-3) is also used suitably.

The organosilicon compound having a cyclic hydrocarbon group can be represented by the following general formula. A _L SiR _4-L where A represents the cyclohydrogen group exemplified by a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group and a substituted indenyl group, and R represents a methyl group, an ethyl group, a propyl group. Groups, alkyl groups such as isopropyl group, butyl group; alkoxy groups such as methoxy group, ethoxy group, propoxy group, butoxy group; aryl groups such as phenyl group; aryloxy groups such as phenoxy group; aralkyl groups such as benzyl group Is shown and represents a hydrocarbon residue or hydrogen having 1 to 24 carbon atoms, preferably 1 to 12 and L is 1
≦ L ≦ 4, preferably 1 ≦ L ≦ 3.

Specific examples of the organic cyclic hydrocarbon compound of the above component C3 include cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, 1,3-dimethylcyclopentadiene, indene, 4-methyl-1-indene, 4,7-. Cyclopolyene or substituted cyclopolyene having 5 to 24 carbon atoms such as dimethylindene, cycloheptatriene, methylcycloheptatriene, cyclooctatetraene, azulene, fluorene and methylfluorene, monocyclopentadienylsilane, biscyclopentadiene Phenylsilane, triscyclopentadienylsilane, monoindenylsilane, bisindenylsilane,
Examples include trisindenylsilane and the like.

The modified organoaluminum compound containing an Al--O--Al bond obtained by reacting the organoaluminum compound of the catalyst component C4 with water is usually called an aluminoxane by reacting an alkylaluminum compound with water. A modified organoaluminum is obtained, which is usually 1 to 100, preferably 1 to 50 Al- in the molecule.
It contains an O-Al bond. The modified organoaluminum compound may be linear or cyclic.

The reaction of organoaluminum with water is usually carried out in an inert hydrocarbon. As the inert hydrocarbon,
Aliphatic, alicyclic and aromatic hydrocarbons such as pentane, hexane, heptane, cyclohexane, benzene, toluene and xylene are preferred. The reaction ratio between water and the organoaluminum compound (water / Al molar ratio) is usually 0.25 / 1 to 1.2.
/ 1, preferably 0.5 / 1 to 1/1.

The inorganic carrier and / or the particulate polymer carrier of the catalyst component C5 means a carbonaceous material, a metal, a metal oxide, a metal chloride, a metal carbonate or a mixture thereof, a thermoplastic resin, a thermosetting resin or the like. Is mentioned. Suitable metals that can be used for the inorganic carrier include:
Examples include iron, aluminum, and nickel. Specifically, SiO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ , TiO
_{2, B 2 O 3, CaO} , ZnO, BaO, ThO 2 and the like or mixtures _thereof, SiO 2 -Al
₂ O ₃ , SiO ₂ —V ₂ O ₅ , SiO ₂ —TiO ₂ , S
_{iO 2 -V 2 O 5, SiO} 2 -MgO, SiO 2 -Cr
₂ O _{3 and the} like. Among these, those containing, as a main component, at least one component selected from the group consisting of SiO ₂ and Al ₂ O ₃ .

As the organic compound, either a thermoplastic resin or a thermosetting resin can be used. Specifically, particulate polyolefin, polyester, polyamide, polyvinyl chloride, poly (meth) acrylic acid methyl ester, Examples thereof include polystyrene, polynorbornene, various natural polymers, and mixtures thereof. The inorganic carrier and / or the particulate polymer carrier can be used as they are, but preferably, as a pretreatment, these carriers are subjected to contact treatment with an organoaluminum compound or a modified organoaluminum compound containing an Al-O-Al bond. After the ingredient C
It can also be used as 5.

The method for producing the ethylene / α-olefin copolymer of the present invention is produced by a gas phase method, a slurry method, a solution method or the like, and is not particularly limited such as a one-step polymerization method and a multi-step polymerization method.

The other (B) ethylene-based polymer of the present invention means (B1) density of 0.86 to 0.50 by the high / medium / low pressure method using a Ziegler type catalyst or the like and other known methods.
A copolymer of 94 g / cm ³ of ethylene and an α-olefin having 3 to 20 carbon atoms and / or (B2) an ethylene-based (co) polymer obtained by a high-pressure radical polymerization method.

(B1) ethylene having a density of 0.86 to 0.94 g / cm ³ and a carbon number of 3 to 3 according to the above-mentioned high / medium / low pressure method using the Ziegler type catalyst or the like and other known methods.
A copolymer of 20 with α-olefin has a density of 0.9.
Linear low density polyethylene (hereinafter referred to as LLDPE) having a density of 1 to 0.94 g / cm ³ , and a density of 0.86 to 0.91 g /
cm ³ ultra-low density polyethylene (hereinafter referred to as VLDPE), ethylene / α-such as ethylene / propylene copolymer rubber and ethylene / propylene / diene copolymer rubber having a density of 0.86 to 0.91 g / cm ^3. Includes olefin copolymer rubber.

LLDPE by the above Ziegler type catalyst means ethylene.α-having a density of 0.91 to 0.94 g / cm ³ , preferably 0.91 to 0.93 g / cm ^3.
It is an olefin copolymer, and the α-olefin has a carbon number of 3 to 20, preferably 4 to 12, and specifically includes propylene, 1-butene, and 4-methyl-.
1-Pentene, 1-hexene, 1-octene and the like can be mentioned.

The ultra-low density polyethylene (VLDPE) using the above Ziegler type catalyst has a density of 0.86 to
0.91 g / cm ³ , preferably 0.88 to 0.905
It is an ethylene-α-olefin copolymer in the range of g / cm ³ , and is linear low-density polyethylene (LLDPE) and ethylene / α-olefin copolymer rubber (EPR, EPD.
It is a polyethylene showing intermediate properties of M).

The ethylene / α-olefin copolymer rubber is an ethylene / propylene copolymer rubber or an ethylene / propylene / diene copolymer rubber having a density of 0.86 to less than 0.91 g / cm ^3. Examples of the ethylene / propylene rubber include a random copolymer (EPM) containing ethylene and propylene as main components, and a diene monomer (dicyclopentadiene, ethylidene norbornene, etc.) as a third component. The random copolymer (EPDM) used as a component is mentioned.

The above-mentioned ethylene (co) polymer by high-pressure radical polymerization means ethylene homopolymer (low-density polyethylene) by high-pressure radical polymerization, ethylene-vinyl ester copolymer, ethylene and α, β-unsaturated carboxylic acid or Examples thereof include a copolymer with the derivative.

The above-mentioned low density polyethylene is produced by a known high pressure radical polymerization method and may be either a tubular method or an autoclave method.

The above-mentioned ethylene / vinyl ester copolymer is produced by a high-pressure radical polymerization method and contains ethylene as a main component and contains vinyl propionate, vinyl acetate, vinyl caproate, vinyl caprylate, vinyl laurate, vinyl stearate. , A copolymer with a vinyl ester monomer such as trifluoroacetic acid hynyl. Among them, particularly preferred is vinyl acetate. A copolymer composed of 50 to 99.5% by weight of ethylene and 0.5 to 50% by weight of a vinyl ester is preferable. Further, the vinyl ester content is preferably 3 to 20% by weight,
Particularly preferably, it is selected in the range of 5 to 15% by weight.

Further, as a typical copolymer of the above ethylene and an α, β-unsaturated carboxylic acid or its derivative, ethylene / (meth) acrylic acid or its alkyl ester copolymer can be mentioned. As these comonomers, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, acrylic acid-n- Butyl, methacrylic acid-n-
Butyl, cyclohexyl acrylate, cyclohexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate,
Glycidyl acrylate, glycidyl methacrylate and the like can be mentioned. Of these, particularly preferred are alkyl esters of (meth) acrylic acid such as methyl and ethyl. In particular, the content of the (meth) acrylate is in the range of 3 to 20% by weight, preferably 5 to 15% by weight.

[0048]

BEST MODE FOR CARRYING OUT THE INVENTION One of the embodiments of the stretch film having a laminated structure of the present invention is a specific (A) ethylene-
A stretch film comprising a laminate of at least two layers, an I-layer containing an α-olefin copolymer and a (B) ethylene-based II layer. The I-th layer is a composition layer of the specific (A) ethylene-α-olefin copolymer alone or the specific (A) ethylene-α-olefin copolymer and (B) an ethylene-based polymer. It may be formed. The composition of the above-mentioned specific (A) ethylene-α-olefin copolymer and (B) ethylene-based polymer has a balance of molding stability, transparency, mechanical strength, tackiness, stretchability, binding property, and the like. In consideration of (A) 98
To 20% by weight, (B) 2 to 80% by weight, preferably (A) 90 to 50% by weight, (B) 10 to 50% by weight, and more preferably (A) 80 to 60% by weight, (B) 20. ~
It is selected in the range of 40% by weight. Also in the II layer, the density (B1) of the Ziegler type catalyst is 0.86 to
0.94 g / cm ³ of ethylene-α-olefin copolymer or (B2) ethylene (co) polymer by high pressure radical polymerization may be used alone or as a mixed composition.

A concrete combination of these is MLL.
/ EVA, (MLL + LD) / EVA, (MLL + L
L) / EVA, (MLL + EVA) / EVA, MLL /
(EVA + LD), MLL / (EVA + LL), (ML
L + EVA) / (EVA + LL), MLL / EEA,
(MLL + LD) / EEA, (MLL + VL) / EE
A, (MLL + EVA) / EEA, MLL / (EVA +
EEA) and the like. (However, MLL: (A) ethylene-α-olefin copolymer of the present invention, EVA: ethylene-vinyl acetate copolymer, LD: high pressure radical method low density polyethylene, LL: linear low density polyethylene, V
L: ultra low density polyethylene, EEA: ethylene-ethyl acrylate copolymer)

In another embodiment of the stretch film having the laminated structure of the present invention, the density of the (B1) Ziegler type catalyst on both surfaces of the I-th layer is 0.86 to 0.94 g / cm ^3.
Of the ethylene-α-olefin copolymer or the (B2) ethylene (co) polymer by high-pressure radical polymerization of at least one (B) ethylene-based polymer, wherein a second layer and a third layer are provided. It is a body stretch film, and the I-th layer, the II-th layer and the III-th layer may be formed of the same kind or different kinds and a mixture layer.

As a concrete combination of these, EVA
/ MLL / EVA, EVA / (MLL + LD) / EV
A, EVA / (MLL + VL) / EVA, LL / (ML
L + EVA) / EVA, EVA / MLL / (EVA + L
D), (EVA + LL) / MLL / (EVA + LL),
EVA / (MLL + EVA) / (EVA + LL), EE
A / MLL / EEA, EEA / (MLL + LD) / EE
A, EEA / (MLL + LL) / EEA, EEA / (M
LL + EVA) / EEA, EEA / MLL / (EVA +
EEA) and the like.

In the present invention, the I-th layer and the II-th layer are used.
It is desirable to add a tackifier to the resin of layer (3), the resin of layer (III) or a composition thereof. As the tackifier,
Examples include tackifiers such as polybutene, castor oil derivatives, sorbitan fatty acid esters, rosins and rosin derivatives, petroleum resins and hydrogenated products thereof, and rubber.
These tackifiers are preferably blended in the range of 0.1 to 20 parts by weight with respect to 100 parts by weight of the resin or resin composition.

With respect to the specific ethylene / α-olefin copolymer of the present invention or the composition thereof, a lubricant, an organic or inorganic filler, an antioxidant, an anti-fogging agent may be used as long as the characteristics of the present invention are not essentially impaired. Agents, organic or inorganic pigments,
Known additives such as a dispersant, a nucleating agent, a foaming agent, a flame retardant, and a crosslinking agent can be added. Among these additives, lubricants and inorganic fillers are preferably used in order to further improve workability. In addition, since the stretch film for grass is required to have an ultraviolet blocking property, it is desirable to blend a pigment.

Examples of the lubricant include fatty acid amides such as oleic acid amide, stearic acid amide, and erucic acid amide; fatty acid glycerin ester compounds such as stearic acid monoglyceride, stearic acid diglyceride, oleic acid monoglyceride, oleic acid diglyceride, and their polyethylenes. Examples thereof include glycol adducts.

Examples of the inorganic fillers include light and heavy calcium carbonate, talc, silica, zeolite, magnesium carbonate, feldspar. As the pigment, carbon black, titanium white, etc., and various commercially available colorant masterbatches are suitably used.

In the method for producing the film of the present invention, the individual films may be laminated using a known inflation molding method, a T-die molding method, a water-cooled film molding method or the like, but preferably a multilayer inflation molding method. And a coextrusion molding method such as a multilayer T-die molding method are preferable. The stretch film of the present invention is preferably used for applications such as stretch films for pallet packaging and stretch films for grass packaging.

[0057]

Next, the present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. The resins used in Examples and Comparative Examples are shown below. The ethylene / α-olefin copolymer of the present invention was polymerized by the following method.

(Preparation of Solid Catalyst) Purified toluene was added to a catalyst preparation device (No. 1) equipped with an electromagnetic induction stirrer under nitrogen,
Then, dipropoxydichlorozirconium (Zr (OP
28 g of r) ₂ Cl ₂ ) and 48 g of methylcyclopentadiene were added, and 45 g of tridecylaluminum was added dropwise while maintaining the system at 0 ° C. After completion of the addition, the reaction system was adjusted to 50
The mixture was stirred at 16 ° C. for 16 hours. This solution is designated as solution A. Next, another catalyst preparation device with a stirrer (No.
Purified toluene was added to 2), and the above solution A and then a toluene solution of 6.4 mol of methylaluminoxane were added and reacted. This is designated as solution B.

Next, under nitrogen, a preparer with a stirrer (No.
Purified toluene was added to 1) and then 400 ° C in advance.
After adding 1400 g of silica (manufactured by Fuji Devison Co., Ltd., grade # 952, surface area 300 m ² / g), which was calcined for a predetermined time, the whole amount of the solution B was added and stirred at room temperature. Then, the solvent was removed by nitrogen blowing to obtain a solid catalyst powder having good fluidity. This is designated as catalyst C.

(Polymerization of Sample) Using a continuous fluidized bed gas phase polymerization apparatus, the polymerization temperature was 70 ° C. and the total pressure was 20 kgf / cm ^2.
G copolymerized ethylene with 1-butene or 1-hexene. The polymerization was carried out by continuously supplying the catalyst C, and the polymerization was carried out while continuously supplying each gas in order to keep the gas composition in the system constant.

(A): Ethylene / α-olefin copolymer Al: Ethylene / 1-butene copolymer Density = 0.920 g / cm ³ , MFR = 2.0 g / 10
min Molecular weight distribution (Mw / Mn) = 2.8 Composition distribution parameter Cb = 1.22 d−0.008 log MFR = 0.917 ODCB soluble content (%) = 3.3 <9.8 × 10 ³ ×
^{(0.9300-d + 0.008logMFR) 2} +
2.0

A2: Ethylene / 1-hexene copolymer Density = 0.921 g / cm ³ , MFR = 2.0 g / 10
min Molecular weight distribution (Mw / Mn) = 2.8 Composition distribution parameter Cb = 1.23 d-0.008 log MFR = 0.919 ODCB soluble content (%) = 3.1 <9.8 × 10 ³ ×
^{(0.9300-d + 0.008logMFR) 2} +
2.0

(B): Ethylene polymer B11: Ziegler-catalyzed linear low-density polyethylene (LLDPE) Comonomer: Butene-1 Density = 0.918 g / cm ³ , MFR = 2.0 g / 10
min Molecular weight distribution (Mw / Mn) = 3.7 Composition distribution parameter Cb = 1.53 d−0.008 log MFR = 0.916 ODCB soluble content (%) = 6.3> 9.8 × 10 ³ ×
^{(0.9300-d + 0.008logMFR) 2} +
2.0

B12: Ziegler-catalyzed ultra-low density polyethylene (VLDPE) comonomer: butene-1 density = 0.900 g / cm ³ , MFR = 2.5 g / 10
min Molecular weight distribution (Mw / Mn) = 4.1 Composition distribution parameter Cb = 1.52 d−0.008 log MFR = 0.897 ODCB soluble content (%) = 30> 9.8 × 10 ³ × (0.
9300-d + 0.008 log MFR) ² + 2.0 =
12.8

B21: Ethylene / vinyl acetate copolymer (EVA) by high-pressure radical polymerization Vinyl acetate content = 5% by weight, MFR = 4.0 g / 10 m
in B22: Low-density polyethylene (LDPE) by high-pressure radical polymerization, density = 0.924 g / cm ³ , MFR = 4.0 g / 10
min B23: Ethylene / ethyl acrylate copolymer (EEA) by high-pressure radical polymerization Ethyl acrylate content = 10% by weight, MFR = 3.0 g
/ 10 min

The test methods used for measuring the physical properties are as follows. (Physical property test method) Density: JIS K6760 conformity MFR: JIS K6760 conformity Tensile strength: ASTM D882 Tensile elongation: ASTM D882 Elmendorf: ASTM D1922 Tear strength Dirt impact strength: ASTM D1709 Self-adhesion width: 2. MD direction of film: 5 cm,
A test piece having a length of 12.5 cm is cut out and divided into two parts in the length direction to have widths of 2.5 cm and 6.25 cm. The ends of the two sets of test pieces are overlapped by a length of 2.5 cm so that the outer side and the inner side of the film winding at the time of molding are in contact with each other. A load of 70 g / cm ² is applied to the overlapped portion and pressure bonding is performed for 5 minutes. Then, it is subjected to a tensile tester within 5 minutes (chuck interval 6.35 mm, tensile speed 125 mm / m
in), the force required for peeling (kg) is measured.

Bindability (holding stress): ASTM D822
According to the procedure described above, the sample is cut at the initial length of 2 at 500 mm / min.
Elongate by 0%. The stress (kg / cm ² ) after standing for 16 hours is used as the holding force. The large holding force indicates that the stretching film has a large tightening force when the product or the like is packaged.

Cohesion (stretch recovery rate): ASTM
The sample is stretched 20% at 500 mm / min according to D882. Leave it as it is for 16 hours, then unload it,
The sample is allowed to stand for another 3 days, and the residual elongation rate (A,%) of the sample is calculated.

[0069]

A high stretch recovery rate indicates that the stretch film has little slack after being wrapped with the stretch film, and has a binding property.

[Examples 1 to 4] Using an air-cooled multi-layer inflation molding apparatus having the resin composition shown in Table 1,
Two-layer or three-layer coextrusion molding was performed to obtain a laminate having a total thickness of 30 μm. Table 1 shows the film physical properties of these laminates, and all satisfy the physical properties required for the stretch film.

[Comparative Example 1] Instead of A1 of Example 1,
Although a linear low density polyethylene with a Ziegler catalyst of B11 was used, it does not satisfy the specific conditions of the present invention, so self-adhesiveness, dirt impact strength, cohesiveness (holding stress,
In terms of stretch recovery rate), the result was insufficient.

[Comparative Example 2] Instead of A2 in Example 2,
Although a linear low density polyethylene with a Ziegler catalyst of B11 was used, it does not satisfy the specific conditions of the present invention, and therefore, in terms of dirt impact strength, Elmendorf tear strength, and cohesiveness (holding stress, stretch recovery rate). The result was insufficient.

[Comparative Example 3] Instead of A1 in Example 3,
B12 Ziegler-catalyzed ultra-low density polyethylene was used, but it does not satisfy the specific conditions of the present invention, and therefore it is unsatisfactory in terms of self-adhesiveness, dirt impact strength, Elmendorf tear strength, and cohesiveness (holding stress). It was a good result.

[Comparative Example 4] Instead of A2 of Example 4,
Although a linear low density polyethylene with a Ziegler catalyst of B11 was used, it does not satisfy the specific conditions of the present invention, and therefore, in terms of dirt impact strength, tensile breaking strength, and cohesiveness (holding stress, stretch recovery rate). The result was insufficient.

[0076]

[Table 1]

[0077]

[Table 2]

[0078]

INDUSTRIAL APPLICABILITY The present invention has a density satisfying specific conditions of 0.86 to 0.94 g / cm ³ and an MFR of 0.1 to 50 g.
Self-adhesiveness and tear resistance by being formed from a laminate of a first layer containing an ethylene / α-olefin copolymer for 10 minutes and a second layer containing (B) an ethylene-based polymer. It is intended to provide a stretch film which is excellent in transmissibility, puncture strength, breaking strength, mechanical strength such as breaking elongation, transparency, stretchability, binding property and the like.

[0079]

[Equation 2]

[Brief description of drawings]

FIG. 1 is an elution temperature-elution amount curve (T
REF curve) is shown.

FIG. 2 shows an elution temperature-elution amount curve (TREF curve) of a copolymer with a typical metallocene catalyst.

[Procedure amendment]

[Submission date] June 25, 1996

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0061

[Correction method] Change

[Correction contents]

(A): Ethylene / α-olefin copolymer A1: Ethylene / 1-butene copolymer Density = 0.920 g / cm ³ , MFR = 2.0 g / 10
min Molecular weight distribution (Mw / Mn) = 2.8 Composition distribution parameter Cb = 1.22 d−0.008 log MFR = 0.917 ODCB soluble content (%) = 3.3 <9.8 × 10 ³ ×
^{(0.9300-d + 0.008logMFR) 2} +
2.0 TREF peak temperature = 79.7, 95.8 ° C.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0062

[Correction method] Change

[Correction contents]

A2: Ethylene / 1-hexene copolymer Density = 0.921 g / cm ³ , MFR = 2.0 g / 10
min Molecular weight distribution (Mw / Mn) = 2.8 Composition distribution parameter Cb = 1.23 d-0.008 log MFR = 0.919 ODCB soluble content (%) = 3.1 <9.8 × 10 ³ ×
^{(0.9300-d + 0.008logMFR) 2} +
2.0 TREF peak temperature = 75.8, 93.8 ° C.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0078

[Correction method] Change

[Correction contents]

[0078]

The present invention is

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0079

[Correction method] Change

[Correction contents]

The density satisfying the specific condition is 0.86 to
0.94 g / cm ³ , MFR 0.1-50 g / 10 min
A first layer comprising an ethylene / α-olefin copolymer,
(B) a laminate with a second layer containing an ethylene polymer
Self-adhesion and tear resistance
, Mechanical strength such as puncture strength, breaking strength, breaking elongation, etc.
Stretch film with excellent transparency, stretchability, and cohesion
Is provided.

Claims (3)

[Claims] 1. A density of 0.86 to 0.94 g / cm.
³ (a) Melt flow rate (MFR) 0.1-50 g /
10 minutes (c) Molecular weight distribution (Mw / Mn) is 1.8 to 3.5 (d) Composition distribution parameter Cb is 1.10 to 2.00 (e) Ortho-dichlorobenzene (ODC) at 25 ° C.
B) The amount X (wt%) of the soluble component and the density d and MFR (melt flow rate) satisfy the following relationship: a) The values of the density d and MFR are d-0.008logM
In the case of FR ≧ 0.93 X <2.0 b) The value of the density d and MFR is d−0.008logM
When FR <0.93 X <9.8 × 10 ³ (0.9300-d + 0.008l)
(ogMFR) ² +2.0 (f) There are multiple peaks of the elution temperature-elution amount curve by the continuous temperature rising elution fractionation method (TREF). (A) Ethylene / α- that satisfies the above (a) to (f) A first layer made of an olefin copolymer, and (B1) a density of 0.86 to 0.9 by a Ziegler type catalyst
4 g / cm ³ ethylene-α-olefin copolymer, (B2) ethylene (co) polymer by high-pressure radical polymerization, and a laminate comprising at least one (B) ethylene-based polymer II layer Stretch film consisting of. 2. The density of the (B1) Ziegler catalyst type catalyst on both surfaces of the I-th layer is 0.86 to 0.94 g / cm ^3.
Ethylene-α-olefin copolymer, (B2) at least one of ethylene (co) polymers by high pressure radical polymerization
A second layer consisting of a seed (B) ethylene polymer and a first layer
The stretch film according to claim 1, which is a laminate having a layer II. 3. (a) Density is 0.86 to 0.94 g / cm.
³ , (a) Melt flow rate (MFR) 0.1 to 50 g /
10 minutes (c) Molecular weight distribution (Mw / Mn) is 1.8 to 3.5 (d) Composition distribution parameter Cb is 1.10 to 2.00 (e) Ortho-dichlorobenzene (ODC) at 25 ° C.
B) Amount of soluble content X (wt%) and density d and MFR (melt flow rate) satisfy the following relationship: a) Density d and MFR values are d-0.008logM
In the case of FR ≧ 0.93 X <2.0 b) The value of the density d and MFR is d−0.008logM
When FR <0.93 X <9.8 × 10 ³ (0.9300-d + 0.008l)
ogMFR) ² +2.0 (f) There are multiple peaks of the elution temperature-elution amount curve by the continuous temperature rising elution fractionation method (TREF). Ethylene / α-olefin copolymerization satisfying the above (a) to (f) The resin composition containing 20% by weight or more of the combined polymer and 80% by weight or less of another ethylene polymer (B).
Stretch film described in.