JP2772655B2 - Polyolefin resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is excellent in extrusion moldability, heat sealability, impact strength characteristics, tensile strength characteristics, transparency, etc. The present invention relates to a polyolefin-based resin composition having mutually contradictory properties.

These are not particularly limited, but are useful, for example, as a composition constituting at least one of a single layer and a multilayer for film molding.

[Conventional technology]

Conventionally, in order to improve the thermal stability, low-temperature strength, impact strength, etc. of crystalline polypropylene (hereinafter abbreviated as PP), one part of ethylene-propylene copolymer rubber (hereinafter abbreviated as EPR) is used. Mixing methods have been proposed. However, in this method, the compatibility between PP and EPR is not always good, and when processed into a thin film, the kneading is not uniform, or the surface is rough and the optical characteristics are greatly deteriorated, and the strength is also insufficient. Only those with low commercial value.

In order to improve these problems, a method of further mixing an amorphous attack polypropylene has been proposed.However, all of them have been improved mainly with PP. Are still problematic.

Further, as a composition for further improving the problems of these compositions, for example, Japanese Patent Publication No. 59-38976 discloses a ternary mixed composition of EVA, an ethylene-α-olefin copolymer elastomer, and polypropylene. is there. Even when this composition is processed into a thin film, a film excellent in stretch processability, low-temperature shrinkage, heat resistance, heat sealability, mechanical strength, and the like is obtained as compared with a conventional polyolefin-based composition. I have. However, at present, with the diversification of packaging and the speeding up of packaging speed, the properties of films made of these compositions are still insufficient, and there is a problem that the film has particularly low waist strength.

In addition, if the composition ratio of a hard resin such as polypropylene is increased to increase the waist strength, the extrudability and stretchability are reduced, the thickness unevenness is increased, and the tear strength is reduced. And the like, there is a problem that the film is easily torn or the impact strength is reduced to be easily broken.

[Problems to be solved by the invention]

From the above, the object of the present invention is to eliminate these problems, that is, it is excellent in extrudability and stretchability, has a large impact strength and a large waist strength of a molded product, and has a heat sealability and a tear strength. An object of the present invention is to provide a polyolefin-based resin composition excellent in properties, cold resistance, transparency, and the like, preferably a polyolefin-based resin composition for film molding.

[Means for solving the problem]

According to the invention, these problems are: low density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-
15 to 45 wt% of at least one polymer (A) selected from the group consisting of acrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-methacrylic acid copolymer, and ionomer resin; Soft elastomer (B) 5 of 60 ° C or less
And 15 wt%, 23 density at ° C. is 0.880~0.920g / cm ^3, a melt index of 0.5 to 5 g / 10 min, the highest melting point of 110 ° C. to 130 DEG ° C. by differential scanning calorimeter (DSC), and Vicat softening 20 to 55 wt% of a copolymer (C) of ethylene and an α-olefin having 4 to 10 carbon atoms having a temperature of 60 to 95 ° C., and either crystalline polypropylene or crystalline polybutene-1 or a mixed weight thereof. (D) 10 to 40% by weight of the polyolefin resin composition.

 Hereinafter, the present invention will be described specifically.

The polymer (A) used in the present invention includes low-density polyethylene, EVA, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-methacrylic acid copolymer. Polymer,
Either an ionomer resin or a mixture thereof.

Low density polyethylene has a melt index of 0.2-2
0, preferably 0.5 to 10, a density of 0.915 to 0.930 g / cm ³ and a Vicat softening point of 95 ° C. or higher.

In ethylene copolymers, the amount of monomers other than ethylene is 2
1212 mol%, M · 1 is 0.2-10. Of these, low-density polyethylene and EVA produced by the high-pressure method are particularly preferred. These have a crystallinity of 40%, preferably 45 to 65%, determined from the melting energy by DSC.

Next, the soft elastomer (B) having a Vicat softening point of 60 ° C. or less refers to a soft elastomer of 1,2-polybutadiene, ethylene and one or more α-olefins selected from α-olefins having 3 to 12 carbon atoms. Refers to a copolymer,
The latter is preferable, and in some cases, the latter may be further copolymerized with a smaller amount of a hydrocarbon having a polyene structure, for example, dicyclopentadiene, 1,4-hexadiene, ethylidene-norbornene and the like. As the α-olefin, propylene, butene-1, hexene-1, 4
-Methylpentene-1, octene-1 and the like, preferably propylene and butene-1.

The ethylene content in the copolymer is from 20 to 93 mol%, preferably from 40 to 90 mol%, more preferably from 65 to 88 mol%.

These copolymers have a density of 0.900 or less, preferably
0.890 or less and the Vicat softening point [ASTMD1525 (load 1k
g value)] is 60 ° C. or less, and is generally substantially amorphous in a rubbery region, and exhibits low-density polyethylene as the component A or low-density crystallinity as the component C described below. It is distinguished from having. Here, the term "substantially amorphous" refers to a substance having a crystallinity of 10% or less.

Preferred are ethylene and propylene or butene-1.
In the case of a copolymer or a compound having a small amount of a diene structure as a copolymer in these, for example, a vanadium compound and a random copolymer polymerized with an organoaluminum compound catalyst having a melt index of 0.1 to 10, Preferably, it is 0.2 to 6 thermoplastic elastomer.

These are not block-shaped like general non-vulcanized rubber, and are preferably supplied in the form of pellets that do not cause cold blow, and have sufficient thermoplasticity that they can be extruded into a single film. .

Further, the polymer (C) is composed of ethylene and α-
It is a copolymer with olefin. Examples of the α-olefin include butene-1, hexene-1, heptene-1, 4-methylpentene-1, octene-1, and the like, and preferably 4-methylpentene-1 and octene-1. The ethylene content in the copolymer is 85 to 98 mol%, preferably 90 to 96 mol%.
Mol%.

One of the properties of these copolymers is that their density at 23 ° C is
0.880~0.920g / cm ^3, and preferably 0.905 to 0.915,
It is more preferably 0.907 to 0.913, and the melt index is preferably 0.5 to 5 g / 10 minutes. In addition, these copolymers have a maximum melting point of 110 ° C. by differential scanning calorimetry (DSC).
130130 ° C. and a Vicat softening point of 60 ° C. to 95 ° C., which is clearly distinguished from a substantially amorphous one in a rubbery region such as the component (B), They have crystallinity, and they are usually 10 to 50%, preferably 15 to 50%.
It has a crystallinity of 45%.

Preferred is a copolymer of ethylene and 4-methylpentene-1 or octene-1, for example, a low-crystalline copolymer prepared by a so-called medium / low pressure method using a titanium compound and an organoaluminum compound catalyst. It is a united product, has a maximum melting point equivalent to that of ordinary linear low-density polyethylene, has a low Vicat softening point, is in the range of 60 to 95 ° C, and has excellent moldability such as stretching. These include, for example, Plastic Engineering Volume 11, P5
9 to 62 ('85), such as VLDPE.

Further, the crystalline polypropylene and the crystalline polybutene of the component (D) are crystalline polymers having high isotacticity.

Polypropylene contains a homopolymer of propylene or a copolymer of propylene and 7 mol% or less of α-olefin, and has a M of 1,0.5 to 20.

The polybutene is different from a low-molecular-weight liquid or wax-like one, and has a butene-1 content of 93 mol% or more and a high molecular weight including a copolymer with other monomers. These are preferably relatively hard polymers having a Vicat softening point of 100 ° C. or higher.

The composition of the present invention comprises the components (A), (B),
It consists of a mixed composition of (C) and (D), and the range of these amounts is such that the component (A) is 15 to 45% by weight, preferably 20 to 40% by weight.
wt%, more preferably 25-35 wt%. The range of the amount of the component (B) is 5 to 15% by weight, preferably 10 to 15% by weight.
~ 15 wt%. The range of the amount of the component (C) is from 20 to
It is 55 wt%, preferably 25-45 wt%, more preferably 30-40 wt%. The range of the amount of the component (D) is 10 to 40% by weight, preferably 20 to 30% by weight.

Here, when the amount of the low-crystalline polymer component (C) is small, the synergistic effect of the mixture cannot be exhibited, and the extrudability, impact strength characteristics, cold resistance, transparency, etc. are reduced. I do. The same applies when the amount of (C) exceeds 55% by weight, and the waist strength and sealing properties of the molded product are also reduced.

The component (D) synergistically improves the tensile strength, impact strength, heat resistance, extrusion moldability, waist strength (elastic modulus), and heat seal temperature range of the mixed composition together with other components, and particularly heat resistance and extrusion molding. The effect is large in the properties, waist strength (elastic modulus), heat sealing temperature range, and the like. In the case of these effects, when the mixing amount is small, for example, the thickness deviation due to the flow characteristics at the time of stretching and in the die becomes large. Further, the effect of the improvement on the heat sealing temperature range and strength is reduced, and the heat resistance is also reduced. On the other hand, if the amount of the component (D) is too large, the extrusion moldability, transparency, cold resistance, impact strength, and the like will be poor.

The component (A) is composed of a specific low-density polyethylene and an ethylene-based copolymer, and synergistically improves the extrusion moldability, heat sealability, transparency, etc. of the mixed composition with other components. In particular, the effect on heat sealability, transparency, and the like is great. When the mixing amount of the component (A) is small, the extrusion moldability is deteriorated, the thickness of the molded product is uneven, and the effect of improving the heat sealing temperature range and the impact strength is reduced. The same is true even when the mixing amount of the component (A) is too large, and the waist strength and the heat sealing property of the molded product are reduced.

Also, when the mixing amount of the component (B) is small, the synergistic effect of the mixture is not exhibited, and the extrusion moldability, impact strength characteristics, transparency and the like are reduced. In addition, the same applies when the mixing amount of (C) is too large, and the waist strength, heat sealing properties, heat resistance, and the like of the molded product are reduced.

Here, the component (C) is composed of the aforementioned four components (A), (B),
It is preferable that the component be the largest amount in the mixture of (C) and (D). Of the four components, component (A) and component (D)
In the case of only mixing, the mixing property and the compatibility are not good, and the above-mentioned synergistic effect is hardly expected. In addition, when the components (B) and (D) and the components (C) and (D) are mixed, the compatibility is slightly improved, but the above-mentioned synergistic effect is hardly expected. Is still inadequate. In addition, component (A)
A mixture of component (B) and component (D), a mixture of component (A), component (C) and component (D), component (B) and component (C)
With the mixture of the component (D) and the component (D), the compatibility and the moldability are improved, and the impact strength or the waist strength is improved with a specific composition. However, both cannot be improved at the same time. Then, the waist strength is reduced, and if the waist strength is to be improved, the impact strength is reduced.

However, component (A), component (B), component (D)
When the component (C) is added to the composition, the disadvantages are remarkably improved, the compatibility and the moldability are improved, the impact strength and the waist strength are simultaneously improved, and the transparency, heat sealability and tensile strength of the molded product are improved. Etc. can also be improved.

It is considered that these reasons are due to complicated interactions such as the crystal structure of each component of the mixture and the dispersion state or orientation state of the mixture.

For example, when the component (A) is a main component, when the above components are melt-kneaded and extruded with an extruder having excellent kneading ability to form a molded product, the inside of the component (D) dispersed in the component (A) It is conceivable that the component (B) is dispersed around the periphery, and the dispersed components (D) are dispersed so that the component (C) is connected to each other and interact with each other. These are processed, for example, into films and other molded products depending on the molding conditions,
When orientation is given, the state of each component is also different.

For example, a relatively high temperature 230 to 2 suitable for the flow of component (D)
When the mixture is extruded from a die for small slits, for example, a film or a sheet having a size of 1.5 mm at a temperature of 60 ° C., and then quenched into a film after applying a constant draw ratio, the amount of the hard component (D) is increased. Depending on, for example, component (D)
When the crystalline polypropylene is mixed at 30 wt%, the crystalline polypropylene of the component (D) delicately orients the dispersed particles in the flow direction in the main component (A), and disperses the dispersed particles. It is considered that the components (B) and (C) may have a linked structure, and exhibit properties in which various properties such as strength are extremely improved (in particular, properties in which both impact strength and waist strength are improved). At this time, since the component (C) has a lower flow orientation than the other components, it is considered that the orientation component and the non-orientation component have a shape as if reinforced with fibers.

The composition of the present invention is a molded article, a film, and can be used freely for other adhesive applications, etc., and is not particularly limited, but it is preferable to use it for a film, for example, as a simple substance rather than an annular die. Inflation by a usual method, for example, an air cooling method, a water cooling method, or the like,
Alternatively, it can be formed by a method of forming a film from a T-die by a casting method or the like, or a method of biaxially stretching these.

Also, when molded as a composite in a multilayered form as at least one of its constituent layers, it is preferably used as a film having processing stability, strength, sealing properties, and optical properties, and as an adhesive layer for the inner and outer layers. Applicable.

In addition, it is very workable and convenient for processing into a molded article having a high degree of orientation in a cold state, for example, a film.

Further, the composition of the present invention may be cross-linked using an organic peroxide cross-linking agent or energy rays, and the obtained cross-linked composition can improve cold resistance and heat resistance in addition to the above-mentioned excellent properties. .

Further, as a preferred example of the composition of the present invention, a nonionic surfactant having a boiling point of 200 ° C. or more in a room temperature liquid as an additive (E) is added to the composition of the present invention in an amount of 0.5 to 5 wt%, preferably 0.8 to 3 wt%.
When wt% is mixed, more preferable properties can be synergistically imparted.

These nonionic surfactants include glycerin,
Sorbitol, pentaerythritol, esters of a polyhydric alcohol such as polyglycerin and a linear saturated fatty acid having 5 to 13 carbon atoms of an alkyl group or a linear unsaturated fatty acid having 17 to 21 carbon atoms of an alkyl group, for example, Polyoxyethylene alkyl phenyl ethers such as polyoxyethylene nonyl ether or polyoxyethylene octyl phenyl ether; and 3 to 10 units of ethylene oxide as polyoxyethylene fatty acid esters. Esters with the above-mentioned fatty acids to which polyoxyethylene has been added are preferred, and these may be used alone or as a mixture.

These are blocking prevention when made into a film,
It exhibits antistatic and antifogging effects and is suitable as a packaging film. In addition, these additives are easily dissolved in any of the components of the mixed resin component, exhibit an effect such that they gradually penetrate into the surface layer from the inner layer, and bleed out, and are usually polyolefin-based. Containing low-molecules, which tend to be found in polymers, is exuded at once, and there is no problem such as stickiness of the surface, and even if the surface is washed away,
The effect lasts.

Further, an alicyclic saturated hydrocarbon, a rosin, a petroleum resin, a terpene resin and the like may be further added as an additive (F) to the composition of the present invention. Its preferred range is 0.5-10 wt
%, More preferably 1 to 7% by weight. These are used alone or in combination, and when used in combination with the above-described nonionic surfactant, the bleeding speed of the nonionic surfactant can be adjusted, and the durability of the effect can be further maintained. it can.

As described above, the composition of the present invention is excellent in processing stability, strength, sealability, and optical characteristics, and can simultaneously improve impact strength and waist strength, particularly when processed into a film. In addition, by giving a high degree of orientation in the cold, it is possible to give low-temperature shrinkage, and it can be used in the same way as PVC shrink film, which is currently used mainly in the field of food shrink packaging. Thus, it is possible to produce a film that can respond to diversification of packaging and high packaging speed.

In addition to the use as a film for shrink wrapping, stretch-shrink wrapping film, other wrapping film, agricultural film, barrier film by adding a barrier layer as a multilayer or its shrink wrapping film, etc. It can be a multilayer film with a resin.

Further, it may be used as a molded product, and the same effect is recognized, and particularly, it is excellent in impact strength.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples, but these do not limit the scope of the present invention.

In addition, the measurement and evaluation in this specification and a text example were based on the following method.

(Evaluation method) Vicat softening point (° C): based on ASTM D1525-58T.

A constant load of 1,000 g is applied to a needle having a flat tip having a cross-sectional area of 1 mm ² , and the temperature is raised in a thermostatic oil bath at a rate of 50 ° C./hour. ).

Density (g / cm ² ): According to ASTM D1505.

 The measurement was performed at 23 ° C using a Shibayama Seisakusho precision gradient tube.

Maximum melting point (° C): Differential scanning calorimeter manufactured by PerkinElmer
Measured on a film sample with a thickness of about 100μ using MODEL DSC-2.

The sample was heated rapidly to 150 ° C. under a stream of nitrogen, kept isothermally at this temperature for 5 minutes, cooled to 50 ° C. at a rate of 10 ° C./min, and then reheated at a rate of 10 ° C./min. The endothermic peak temperature was taken as the maximum melting point. (Hereinafter abbreviated as MP) Crystallinity: The heat of fusion ΔH measured by the above-mentioned DSC is measured, and the crystallinity is calculated using the heat of fusion ΔHn of the crystal components in Table 11.37 of Chemical Handbook Application (edited by The Chemical Society of Japan), page 836. (%) = ΔH / ΔHn × 100.

Melt index (g / 10 minutes): Conforms to ASTM D1238-52T.

Under the conditions of a temperature of 190 ° C. and an extrusion load of 2160 ± 10 g, the weight of the resin constantly extruded was expressed in terms of the number of grams extruded per 10 minutes. (Hereinafter abbreviated as MI) Thickness deviation (%) in the width direction of the film: When measuring the thickness of 40 points at intervals of 20 mm in the width direction and repeating this three times in the flow direction,
The thickness from the average thickness was defined as ± ×%.

Variation in film fold width (%): A value obtained by measuring the fold width continuously over 20 m, dividing the maximum and minimum difference R (mm) by the average fold width, and multiplying by 100.

Haze (%): Measured according to ASTM D1003-52.

Gloss (%): Measured according to ASTM D2457-70.

Tensile strength (kg / mm ² ): Measured according to ASTM D-882.

Waist strength (1% tensile modulus kg / mm ² ): Measured according to ASTM D-882.

Drop strength (kg · cm): Measured in accordance with ASTM D1709-67.

Elmendorf tear strength (g): Measured according to ASTM D1922-67.

Heat sealing range: Bar type sealer (seal width 5m)
The temperature range in which the temperature of (m) is changed to thereby preferably seal is shown.

The lower limit is a temperature at which the film is not sealed to a certain strength by peeling, and the upper limit is a value indicating heat resistance at which the material is melted and cut by heat and cannot have a certain sealing strength.

The bar pressure was 1 kg / cm ³ and the time was appropriately adjusted.

 Hereinafter, the resins used in the examples are described.

a ₁ : EVA [vinyl acetate content 3.5 mol%, MI, 2.0] a ₂ : Low density polyethylene (LDPE) [MI, 2.0, density 0.918
g / cm ³ , MP, 103 ° C.] a ₃ : Ethylene-ethyl acrylate copolymer (EEA) [ethyl acrylate content 5.0 mol%, MI, 1.5] a ₄ : ionomer resin (I ₀ ) [ethylene-meta Acrylic acid copolymer Na neutralized type, methacrylic acid content 6.6 mol%, MI, 1.0, degree of neutralization 25%, degree of saponification 50%] b ₁ : Ethylene-α-olefin copolymer elastomer [α-olefin Contains 15 mol% of propylene and 2 wt% of ethylidene norbornene. MI, 0.45,
Density 0.88 g / cm ³ , Vicat softening point 40 ° C or less] c ₁ : Ethylene-α-olefin copolymer (VLDPE) with low crystallinity [MI, 2.2, density 0.910 g / cm ³ , Mitsui Petrochemical Company Ltd. Ultzex 1020L] c _2: VLDPE [MI3.6, density 0.910 g / cm ^3, Mitsui petrochemical Co., Ltd. Ultzex 1030L] c _3: VLDPE [MI3.3, density 0.912 g / cm ^3, Dow chemical Athein 4002) c ₄ : VLDPE [MI, 1.0, density 0.912 g / cm ³ , Athein 4001 from Dow Chemical Co., Ltd.) c ₅ : VLDPE [MI 0.9, density 0.909 g / cm ³ , Excell manufactured by Sumitomo Chemical Co., Ltd. CN1003] c ₆ : VLDPE [MI, 0.8, density 0.906 g / cm ³ , Nackflex DFDA-1137NT manufactured by Union Carbide] d ₁ : crystalline polypropylene (IPP) [ethylene random copolymerization of 4 wt%, MFR3.3 , Vicat softening point 150 ° C] d ₂ : crystalline polybutene-1 (PB-1) [butene-1 content
96 mol%, density 0.905 g / cm ³ , MI, 1.0] d ₃ : IPP (ethylene copolymerized with 5 wt%, MFR 7.0, density 0.900 g /
cm ³ , Vicat soft point 125 ° C.] Example 1 Ethylene-vinyl acetate copolymer (EVA, a ₁ ): 25 wt% and ethylene-α-olefin copolymer elastomer (b ₁ )
15 wt%, crystalline ethylene-α-olefin copolymer (VL
DPE, c ₂₎ 40wt%, crystalline polypropylene (d ₁₎ 20wt%
Is mixed and plasticized and kneaded at a cylinder head maximum temperature of 240 ° C. with a mixing head type screw having a diameter of 65 mm and L / D = 37, and extruded from an annular die having a slit of 100 mm and a diameter of 1.0 mm to form air inside. Was added, and the mixture was rapidly cooled to obtain a uniform film having a diameter of 400 mm and a thickness of 50 μm. The film was continuously wound into a roll.

Film forming processability is good and stable, and film thickness deviation in the width direction of the film is ± 2.5%, and variation in folding width is 4%.
Was uniform.

 The properties of this film were as follows.

Haze: 1.6%, Gross: 110%, Drop strength (hereinafter abbreviated as dirt strength): 41 kg · cm, Waist strength (1% tensile elastic modulus, vertical / horizontal): 33/30 (kg / mm ² ) tensile Strength: 4.5 / 4.0
(Kg / mm ² ), the heat sealing range was as wide as 110 to 260 ° C., and heat resistance was also exhibited.

Examples 2 to 11 In the same manner as in Example 1, a film having the composition shown in Table 1 was obtained, and the obtained properties are shown in Table 2.

In each case, the processing stability of film formation is good, there is little unevenness in the width direction of the film, and the effect of improving dart strength and waist strength (1% tensile modulus) is large. In addition, the heat sealing temperature range is 110 to 260 ° C., respectively, the sealing strength is strong, and there are no problems such as a hole in the sealing portion in this temperature range.

Examples 12 to 26 Films were formed by using the same method as in Example 1 and changing the composition ratio of the resin composition of Example 1 as shown in Table 3, and the obtained characteristics are shown in Table 4.

As a result, the processing stability of the film formation was good, and the uneven thickness and the variation in the folding width were small at any composition ratio.

Further, it can be seen that within this range of composition ratio, a molded article having excellent transparency and gloss and excellent both of the usually contradictory properties of dart strength and waist strength (1% tensile modulus) can be obtained. Further, in the range of these composition ratios,
Each had a wide heat sealing temperature range of 110 to 260 ° C. and strong sealing strength.

In addition, when the orientation state of each composition component was examined by a polarization fluorescence method in the composition of Example 19, the EVA, polypropylene, ethylene-α-olefin copolymer elastomer was oriented in the flow direction, but was partially crystalline. It was observed that the ethylene-α-olefin copolymer was hardly oriented. The dart strength of this composition was 42 kg · cm, which was the strongest among the compositions of the examples.

Examples 27 to 42 The compositions of Example 1 and the compositions of Examples 12 to 26 (Table 3) were
Melt plasticization was performed using the same extruder as in Example 1, 2.0 wt% of diglycerin-monooleate was injected as a liquid additive in the middle of the extruder, and the kneaded composition was similarly extruded, quenched, and rapidly cooled to obtain a 90 μm thick raw material. Got anti. Continue to reduce this stock to 70
Heat using hot air at ℃, blow air inside 3.2 times vertical, 4.0 times horizontal, draw cold, fold, and then
And heat-set using hot air to obtain a film having a thickness of 11 μm.

 Table 5 shows the properties of the obtained film.

In each case, the stability of the film formation was good, and the uneven thickness and the variation in the folding width were small.

In addition, despite the thickness of each film being as thin as 11 μm, the dart strength exceeded 30 kg · cm, the waist strength (1% tensile modulus) was strong, and the tear strength was also very excellent. Each of these films had a wide heat-sealing temperature range of 110 to 260 ° C. and a high sealing strength. In addition, the obtained film has a shrinkage ratio of 20-30% at 60 ° C, a heat shrinkage stress of 100-150 g / cm ² (length / width average), and a sufficient low-temperature shrinkage as a film for shrink packaging. Combined with excellent properties such as dart strength, waist strength, tensile strength, tear strength, transparency, heat sealability, etc., it is very useful as a packaging film corresponding to diversification of shrink packaging and speeding up of packaging speed. It is.

Comparative Examples 1 to 10 Films having the compositions shown in Table 6 were formed in the same manner as in Example 1, and the properties obtained are shown in Table 7.

As a result, there was a problem with respect to the film formation processing stability except for Comparative Example No. 7, and the uneven thickness was not very good.

In particular, in Comparative Examples 1, 2, and 3, the kneading was not uniform, and the optical characteristics (haze, gloss) were poor. In Comparative Examples 4, 5, 6, and 9, the waist strength of the film was small.
Difficult to handle.

Further, the films of Comparative Examples 7, 8, and 10 had better optical characteristics than the other films, but still had insufficient dirt strength and waist strength.

The heat sealing temperature range was set as Comparative Examples 1, 2, 3, 8, 10
However, in the high temperature range of 160 to 230 ° C., the strength was not so strong. Comparative Examples 4, 5, 6, and 9 could be sealed in a low temperature range of 100 to 150 ° C., but had no heat resistance and were easy to form holes.

Comparative Examples 11 to 20 In the same manner as in Example 1, films having the compositions shown in Table 8 were formed, and the properties of the obtained films are shown in Table 9.

All of the films had poor film-forming stability and obtained only large thickness deviations.

Further, these films have relatively good compatibility of the resin components and good optical properties, but are difficult to handle due to low dart strength and low waist strength.

Comparative Examples 21 to 30 Films were formed from the compositions of Comparative Examples 11 to 20 (Table 8) in the same manner as in Example 27 to obtain films having an average thickness of 11 µm.
Table 10 shows the properties of the obtained film.

As a result, all of the films were inferior in film formation processing stability, and the thickness deviation of the films was large. Also,
Although these films have relatively good optical properties, their dart strength is weak and their tear strength is not very strong.Thus, if you try to package contents with protrusions, or if you try to increase the packaging speed, the films will break, There was a hole and it could not be used.

In particular, Comparative Examples 21, 25, 26, and 30 have low waist strength,
In addition to the above problems, there is a problem that it is difficult to handle.

〔The invention's effect〕

As described above, the composition according to the present invention is excellent in extrudability and heat sealability, impact strength properties, tensile strength properties, transparency and the like.

In particular, the composition of the present invention has excellent properties at the same time, which are usually contradictory properties such as waist strength and impact strength of a molded product,
It is very useful as a composition for a wide range of plastic molding and processing fields, especially for sheet and film molding.

Claims (1)

(57) [Claims] 1. Low density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-methacrylic acid copolymer At least one polymer selected from the group consisting of a polymer and an ionomer resin (A) 15 to 45 wt%, and a soft elastomer (B) 5 having a Vicat softening point of 60 ° C. or less.
15wt%, density at 23 ℃ is 0.880 ~ 0.920g / cm ³ , melt index is 0.5 ~ 5g / 10min, maximum melting point by differential scanning calorimeter (DSC) is 110 ℃ ~ 130 ℃, and Vicat softening point But
20 to 55 wt% of a copolymer (C) of ethylene and an α-olefin having 4 to 10 carbon atoms at 60 to 95 ° C., and either crystalline polypropylene or crystalline polybutene-1 or a mixed polymer thereof ( D) A polyolefin resin composition comprising 10 to 40% by weight.