JPH10235814A - Multilayer film for rubber packaging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a film, which is excellent in mechanical strength and impact resistance and hard to be broken at the packaging of a rubber and easily melted and dispersed in the rubber at the kneading of the rubber by a method wherein the film consists of a layer made of high-pressure-produced low-density polyethylene and a layer mainly made of ethylene-α-olefin copolymer having specified characteristics. SOLUTION: This film consists of a high-pressure-produced low-density polyethylene and an ethylene-α-olefin copolymer. The ethylene-α-olefin copolymer has a density of 0.880-0.915g/cm<3> , a melt flow rate at 190 deg.C under the load of 2.16kg of 0.01-200g/10min, a melt flow rate ratio between the melt flow rate at 190 deg.C under the load of 2.16kg and that at 190 deg.C under the load of 21.6kg of 10-20 and a molecular weight distribution of 2.0-4.0. As a result, this film has excellent mechanical strength and impact resistance and is hard to be broken at the packaging of a rubber and easily melt and disperse in the rubber at the kneading of the rubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an optimum impact resistance,
The present invention relates to a multilayer film for rubber packaging which has tensile strength and is easily melted and dispersed with rubber.

[0002]

2. Description of the Related Art When shipping rubber such as polybutadiene in the form of a bale, it may be shipped packed in a polyethylene film. In the state where the rubber is packaged with a polyethylene film,
A method of putting into a kneader such as a Banbury mixer and using it is used. In this case, the polyethylene film used for packaging needs to be melted during kneading and dispersed in rubber. Therefore, a high-pressure low-density polyethylene having a low melting point is generally used.

However, when a film made of low-density high-pressure polyethylene having a low melting point is used for packaging synthetic rubber such as polybutadiene, the impact resistance and tear strength are low, and the weight of the rubber due to its own weight at the time of stock or transportation is low. There was a problem that the packaging film was easily damaged by the cold flow. In addition, a film made of a linear low-density polyethylene produced with a Ziegler-based polymerization catalyst has a high melting point and is hardly melted during kneading and sometimes remains in rubber as impurities.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the conventional film, is excellent in mechanical strength and impact resistance, is hardly damaged during rubber packaging, and melts and disperses with rubber during kneading of rubber. It is an object of the present invention to provide a multilayer film suitable for easy rubber packaging.

[0005]

SUMMARY OF THE INVENTION The present invention provides a multilayer rubber packaging comprising a layer A composed of high-pressure low-density polyethylene and a layer B composed mainly of an ethylene-α-olefin copolymer having the following characteristics. It is about a film.

Further, the present invention provides that a layer B composed mainly of an ethylene-α-olefin copolymer having the following properties is used as a core material, and a layer A composed of high-pressure low-density polyethylene is used as a coating layer. The present invention relates to a multilayer film for rubber packaging.

Layer B: ethylene-α-olefin copolymer; (B-1) density (d) = 0.880 to 0.915 (g /
cm ³ ) (B-2) Melt flow rate at 190 ° C., 2.16 kg load (MFR2.16) = 0.01 to 200 (g / 10 min) (B-3) Melt flow rate at 190 ° C., 2.16 kg load (MFR21.6) / (MFR21.6) / (MFR2.16) = 10-20 (B-4) Molecular weight distribution (MFR21.6) / Melt flow rate (MFR21.6) at 190 ° C. under a load of 21.6 kg (Mw / Mn) = 2.0-4.0

[0008] More preferably, the present invention relates to a multilayer film for rubber packaging, wherein the ethylene-α-olefin copolymer is produced by a metallocene catalyst system.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the high-pressure low-density polyethylene of the layer A of the present invention include those produced by high-pressure radical polymerization.

The high-pressure low-density polyethylene of the layer A in the present invention includes, in addition to a homopolymer of ethylene, a copolymer with another monomer such as an ethylene-vinyl acetate copolymer. When an ethylene-vinyl acetate copolymer is used, the amount of the repeating unit derived from vinyl acetate in the copolymer is usually preferably 20% by weight or less.

As the high-pressure low-density polyethylene of the layer A of the present invention, those having the following characteristics can be preferably used.

Layer A: high-pressure low-density polyethylene; (A-1) density (d) = 0.910 to 0.935 (g /
cm ³ ), particularly preferably 0.915 to 0.930 (g)
^{/ Cm 3) (A-2} ) 190 ℃, melt in 2.16kg load flow rate (MFR2.16) = 0.01~200 (g / 10min), particularly preferably 0.01~10 (g / 10min)

Among the above properties, (1) if the density is smaller than the above range, the minimum rigidity required at the time of molding cannot be obtained, and if it is larger than the above range, the impact resistance is poor.

(2) If MFR2.16 is smaller than the above range, the fluidity is poor and molding becomes difficult, and if it is larger than the above range, the impact strength is low.

Ethylene-α which is the main component of the layer B of the present invention
-The olefin copolymer has the following specific range.

Layer B: ethylene-α-olefin copolymer; (B-1) density (d) = 0.880 to 0.915 (g /
cm ³ ), preferably 0.895 to 0.915 (g / c
m ³ ), more preferably 0.895 to 0.915 (g)
/ Cm ³⁾ than (B-2) 190 ℃, melt in 2.16kg load flow rate (MFR2.16) = 0.01~200 (g / 10min), preferably 0.1~30 (g / 10min) (B-3) Ratio of melt flow rate (MFR2.16) at 190 ° C and 2.16 kg load to melt flow rate (MFR21.6) at 190 ° C and 21.6 kg load (MFR21.6) / (MFR2 .16) = 10-20 (B-4) Molecular weight distribution (Mw / Mn) = 2.0-4.
0, preferably 2.0 to 3.7

Among the above-mentioned properties, (1) if the density is smaller than the above range, the film becomes weak and the packaging suitability is not obtained, and if it is larger than the above range, the impact resistance is poor and the dispersion with rubber is poor. Is not enough.

(2) If the MFR 2.16 is smaller than the above range, the fluidity is poor and molding is difficult. If the MFR 2.16 is larger than the above range, the impact strength is poor and the stability of bubbles during inflation molding is low.

(3) When (MFR21.6) / (MFR2.16) is larger than the above range, the mechanical properties of the film are deteriorated and the film is easily damaged.

(4) If the molecular weight distribution (Mw / Mn) is larger than the above range, the mechanical properties of the film are reduced and the film is easily damaged.

Further, as the ethylene-α-olefin copolymer used in the rubber packaging film of the present invention, those having the following specific range can be preferably used. (B-5) Standard deviation σ ≦ 17 of the elution amount with respect to the elution temperature obtained by TREF, particularly preferably σ ≦ 16

In the above characteristics, (5) if the standard deviation σ of the elution amount with respect to the elution temperature is larger than the above range, the resistance of feeding out the film at the time of lapping becomes large, and the film is easily cut.

Ethylene-α which is a main component of the layer B of the present invention
Examples of the olefin copolymer include a copolymer of ethylene and an α-olefin obtained by polymerization in the presence of a so-called single-site catalyst such as a metallocene catalyst system.

The α-olefin of the copolymer of ethylene and α-olefin includes propylene, butene-1, pentene-1, hexene-1, 4-methylpentene-1, and octene-1.
And α-olefins having 3 to 10 carbon atoms such as

The repeating unit derived from the α-olefin in the copolymer of ethylene and α-olefin usually contains 30% by weight or less, preferably 25% by weight or less, more preferably 20% by weight or less. I have. The α-olefin may be used alone or in combination of two or more in the ethylene-α-olefin copolymer.

As the single-site catalyst, a combination of a metallocene compound of a transition metal of Group IV or V of the periodic table with an organoaluminum compound and / or an ionic compound is used.

The transition metals of Groups IV or V of the Periodic Table include:
Titanium (Ti), zirconium (Zr), hafnium (H
f) and vanadium (V) are preferred.

The metallocene compound is a compound which is cross-linked by at least one cyclopentadienyl group, substituted cyclopentadienyl group, hydrocarbyl silicon or the like, and which is obtained by cross-linking a cyclopentadienyl group to oxygen, nitrogen and phosphorus atoms. Any known metallocene compound having a compound as a ligand can be used.

Specific examples of these metallocene compounds include dimethylsilyl (2,4-dimethylcyclopentadienyl) (3 ', 5'-dimethylcyclopentadienyl) zirconium dichloride, dimethylsilyl (2,4-dimethyl Cyclopentadienyl) (3 ', 5'-dimethylcyclopentadienyl) silicon-bridged metallocene compounds such as hafnium dichloride, ethylenebisindenyl zirconium dichloride, ethylenebisindenyl hafnium dichloride, ethylenebis (methylindenyl) zirconium Examples include indenyl crosslinked metallocene compounds such as dichloride and ethylenebis (methylindenyl) hafnium dichloride.

The organoaluminum compound used in combination with the metallocene compound in the present invention includes a compound represented by the following general formula:
A linear or cyclic polymer represented by Al (R) O-) n (R is a hydrocarbon group having 1 to 10 carbon atoms, including those partially substituted by halogen atoms and / or RO groups; .N
Is the degree of polymerization and is 5 or more, preferably 10 or more)
And specific examples include methylalumoxane, ethylalumoxane, isobutylethylalumoxane, wherein R is a methyl, ethyl, or isobutyl group, respectively.

Further, other organic aluminum compounds include trialkylaluminum, dialkylhalogenoaluminum, sesquialkylhalogenoaluminum, alkenylaluminum, dialkylhydroaluminum, sesquialkylhydroaluminum and the like.

The ionic compound is represented by the general formula: A +.
A + is an oxidizing cation of an organic compound, an organometallic compound, or an inorganic compound, or a Bronsted acid composed of a Lewis base and a proton, and reacts with a metallocene ligand anion to form a metallocene cation. Can be generated. C- is an anionic component of the ionic compound. Specific examples thereof are disclosed in
No. 253711, JP-A-4-305585,
JP-A-5-507756, JP-A-5-5029
No. 06 can be used.

In particular, an ionic compound of a tetrakis (pentafluorophenyl) borate anion and a triphenylcarbonium cation or a dialkylanilinium cation is preferred. These ionic compounds can be used in combination with the aforementioned organic aluminum compounds.

Ethylene and α by single-site catalyst
-As a method of copolymerizing with olefin, various well-known methods can be adopted, and fluidized bed gas phase polymerization or stirring gas phase polymerization in an inert gas, slurry polymerization in an inert solvent, monomer And the like, as a solvent.

The layer B of the present invention contains an ethylene-α-olefin copolymer as a main component. In particular, it preferably contains the ethylene-α-olefin copolymer in an amount of 10% by weight or more, more preferably 25% by weight or more, and particularly preferably 70% by weight or more.

If the ethylene-α-olefin copolymer is smaller than the above range, impact resistance and tensile strength are not sufficient.

The layer B of the present invention may further contain, in addition to the above-mentioned ethylene-α-olefin copolymer, a polymer other than the ethylene-α-olefin copolymer having good dispersibility in melt kneading with rubber.

Examples of the polymer having good dispersibility in melt-kneading with the rubber include high-pressure low-density polyethylene.

High-pressure low-density polyethylene is preferably added to the ethylene-α-olefin copolymer in an amount of 90% by weight.
Or less, particularly preferably 75% by weight or less.

In the multilayer film for rubber packaging of the present invention, a layer B composed mainly of the above-mentioned ethylene-α-olefin copolymer is used as a core material, and a layer A composed of the high-pressure low-density polyethylene is used as a coating layer. This is preferable because the slipperiness of the surface is improved and the workability during rubber packaging can be improved.

Each composition used in the layers A and B of the present invention is as follows:
A mixture obtained by mixing and kneading the components using various kneaders such as a Banbury mixer, a roll mixer, a kneader, a high-speed rotary mixer, and an extruder, preferably a single-screw or twin-screw extruder can be used. Further, a material kneaded during inflation molding or T-die molding can be used.

In the multilayer film for rubber packaging of the present invention, the film thickness is preferably in the range of 15 to 300 μm, more preferably in the range of 15 to 200 μm, and particularly preferably in the range of 20 to 150 μm.

The thickness of the layer B of the present invention is preferably from 10 to
120 μm range, more preferably 10-100 μm
And particularly preferably in the range of 15 to 75 μm.
When the thickness of the layer B is smaller than the above range, the impact resistance becomes poor.

The multilayer film for rubber packaging of the present invention can be preferably used for packaging synthetic rubber such as polybutadiene rubber, styrene butadiene rubber, polyisobutylene rubber, chloroprene rubber or rubber such as natural rubber. In particular, polybutadiene rubber is preferred.

The method for producing the multilayer film for rubber packaging of the present invention is not particularly limited, and methods conventionally used in the production of multilayer films, such as an inflation film forming method, a T-die film forming method and a film of each layer, may be used. A lamination method or the like can be used.

The multilayer film for rubber packaging of the present invention comprises A
Layer, layer B, or all layers, if necessary,
Lubricants, antiblocking agents, antioxidants, ultraviolet absorbers, heat stabilizers, flame retardants, inorganic and organic fillers, antistatic agents, coloring agents, and the like can be added.

[0047]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The method for measuring the properties of the components constituting each layer, the method for measuring physical properties, and the resin material used in the present invention are as follows.

The characteristics of the resin material constituting each layer used in the present invention were determined by the following measuring methods. The results are shown in Table 1. (1) Density: 190 according to JIS K7112
Melt flow rate (MF at 21.6 kg load)
R) The strand obtained at the time of the measurement was heat-treated at 100 ° C. for 1 hour, and the sample which was gradually cooled to room temperature over 1 hour was measured using a density gradient tube. (2) Melt flow rate (MFR2.16): JIS K7
In accordance with No. 210, using a melt indexer, 19
It was determined by measuring the weight of the resin extruded into a strand in 10 minutes under a load of 2.16 kg at 0 ° C. (3) Melt flow ratio (MFR21.6) / (MFR2.16): In the same manner as in the above method (2), the weight of the resin obtained with a load of 21.6 kg was obtained by the resin obtained in the above (2). It is the value divided by the weight. (4) Molecular weight distribution: WATERS 15 as a measuring device
Using 0CV, column PL Mixed B, temperature 135 ° C,
The measurement was performed under the conditions of the solvent o-dichlorobenzene. (5) Standard deviation σ of elution amount with respect to elution temperature obtained by TREF: Cross sorter CFC manufactured by Mitsubishi Chemical Corporation
Using T150-A, elution derivative plots at 1 ° C intervals were obtained under the following conditions. From the obtained elution differential plot, the standard deviation σ of the elution amount with respect to the elution temperature was determined. TREF stands for TemperatureRising
It is an abbreviation for Elution Fraction. Measurement conditions: Column Shodex AT-80M / S ×
3 solvents o-Dichlorobenzene Detector Infrared absorption detection method Elution temperature 0-135 ° C 28 fractions Data processing method Cross fractionator CFC T150-
The one attached to A was used.

The method for measuring the characteristic values of the films obtained in Examples and Comparative Examples will be described. [Impact strength (gf)] The impact strength was measured according to JIS K7124A method. [Tear strength (Kgf / cm)] JIS K7 by Elmendorf method
128. [Tensile strength (Kgf / cm ² ), elongation (%)] ASTM D882
Was performed according to the tensile test.

Examples 1 to 4 and Comparative Examples 1 to 3 Using the materials shown in Table 1, 50 mm manufactured by Modern Machinery
Films having each thickness shown in Table 2 were obtained using a φ inflation molding machine. The thickness of each layer of the multilayer film was measured with a deflection microscope.

Table 2 shows the characteristics of the films of Examples 1 to 3 and Comparative Example 1.

The surface of a 335 mm × 670 mm × 210 mm rectangular veil of synthetic polybutadiene rubber was covered with the multilayer film obtained in the examples or comparative examples to prevent the veil from adhering. The state of the film during transportation and storage of the veil covered with this film was observed, and the results are shown in Table 4. ○: Damage of the film, no cutting ×: Damage to a part of the film, cutting

A material in which the surface of a 335 mm × 670 mm × 210 mm rectangular synthetic polybutadiene rubber veil was covered with the multilayer film obtained in the examples or comparative examples was placed in a Banbury mixer heated to 110 ° C., and the synthetic polybutadiene rubber was placed. And the state of melt dispersion of the multilayer film was observed. The results are shown in Table 4. ：: Homogeneously dispersed ×: Impurities of the film were present in the rubber

[0054]

[Table 1]

[0055]

[Table 2]

[0056]

[Table 3]

[0057]

[Table 4]

[0058]

The multilayer film for rubber packaging of the present invention is excellent in mechanical strength and impact resistance, is not easily damaged during rubber packaging, and easily melts and disperses with rubber during rubber kneading.

Claims (3)

[Claims] 1. A multilayer film for rubber packaging, comprising a layer A composed of high-pressure low-density polyethylene and a layer B composed mainly of an ethylene-α-olefin copolymer having the following properties. B layer: ethylene-α-olefin copolymer; (B-1) density (d) = 0.880 to 0.915 (g /
cm ³ ) (B-2) Melt flow rate at 190 ° C., 2.16 kg load (MFR2.16) = 0.01 to 200 (g / 10 min) (B-3) Melt flow rate at 190 ° C., 2.16 kg load (MFR21.6) / (MFR21.6) / (MFR2.16) = 10-20 (B-4) Molecular weight distribution (MFR21.6) / Melt flow rate (MFR21.6) at 190 ° C. under a load of 21.6 kg (Mw / Mn) = 2.0-4.0 2. A multilayer film for rubber packaging comprising, as a core material, a layer B mainly composed of an ethylene-α-olefin copolymer having the following characteristics, and a layer A composed of high-pressure low-density polyethylene. B layer: ethylene-α-olefin copolymer; (B-1) density (d) = 0.880 to 0.915 (g /
cm ³ ) (B-2) Melt flow rate at 190 ° C., 2.16 kg load (MFR2.16) = 0.01 to 200 (g / 10 min) (B-3) Melt flow rate at 190 ° C., 2.16 kg load (MFR21.6) / (MFR21.6) / (MFR2.16) = 10-20 (B-4) Molecular weight distribution (MFR21.6) / Melt flow rate (MFR21.6) at 190 ° C. under a load of 21.6 kg (Mw / Mn) = 2.0-4.0 3. The multilayer film for rubber packaging according to claim 1, wherein said ethylene-α-olefin copolymer is produced by a metallocene catalyst system.