JPWO2007049734A1 - Polyethylene resin composition and film thereof - Google Patents

Abstract

According to the present invention, linear low density polyethylene (A) having a melting point (Tm) of 110 ° C. or less by differential scanning calorimetry (DSC) is 20 to 99.85% by weight; modification having a polar functional group in the molecule Low density polyethylene (B) 0.05 to 40% by weight; and a polyethylene resin composition comprising 0.1 to 40% by weight of organically modified layered silicate (C) obtained by modifying layered silicate with a cationic surfactant Things are provided.

Description

  The present invention relates to a polyethylene resin composition having excellent physical properties such as elastic modulus and a film thereof. More specifically, the present invention relates to a multilayer film that has characteristics suitable for shrink packaging as a packaging material and is mainly used for food packaging applications.

  Polyolefin resins typified by polyethylene, polypropylene, and the like are used in various applications such as packaging materials, automotive materials, and household appliance materials. In order to improve the mechanical properties of these polyolefin resins, methods for mixing inorganic fillers such as talc and glass fibers have been studied. However, since these inorganic fillers aggregate in the polyolefin resin on the order of micrometers, it is necessary to add a large amount of inorganic fillers in order to obtain a sufficient effect of improving physical properties. Therefore, there has been a problem that it is not suitable for applications that require weight reduction and transparency. In particular, when the inorganic filler is present in a large amount and agglomerated as described above in a film having a thickness of about 10 μm, which is used for food packaging, the transparency is deteriorated and the contents to be packaged are visually recognized. There were problems such as difficulty.

  On the other hand, in a composite material obtained by melt-kneading a layered silicate organically treated with a cationic surfactant into a polar resin such as nylon, the layered silicate is dispersed in the resin on the nanometer order. Therefore, it has been reported that mechanical properties such as the elastic modulus of the resin can be improved with a relatively small addition amount. However, this method is limited to polar resins having a high affinity with the layered silicate, and cannot be applied to polyolefin resins such as polyethylene and polypropylene having poor polarity.

  In order to solve this problem, Patent Document 1 discloses a block copolymerization or graft copolymerization of a monomer (for example, styrene) whose unsaturated carboxylic acid or its derivative and the product of the reactivity ratio thereof are 1 or less. A method of melt-kneading a polymerized copolymer-modified polyolefin resin and a modified layered silicate is disclosed. According to this method, it is reported that the layered silicate as the filler can be uniformly dispersed in the polyolefin resin, and the obtained polyolefin composite material is excellent in elastic modulus and heat resistance. However, this method has no effect unless block copolymerization or graft copolymerization of two kinds of unsaturated carboxylic acid or a derivative thereof and a monomer such as styrene. Therefore, there is a problem that the manufacturing process is complicated. Furthermore, since the degree of modification in the modified polyolefin is high, there has been a problem that characteristics of the original polyolefin such as hydrophobicity are lost.

  On the other hand, Patent Document 2 discloses a nanocomposite based on clay, polymer matrix, and block copolymer or graft copolymer having a layered structure and a cation exchange capacity of 30 to 250 milliequivalent per 100 grams. Yes. The nanocomposite material comprises one or more first structural units in which the block copolymer or graft copolymer is miscible with the clay and one or more second structural units that are miscible with the polymer matrix. According to this method, clay can be mixed extremely uniformly into the matrix polymer, and the resulting composite material is said to have high heat resistance and mechanical strength.

  Further, Patent Document 3 discloses a polyolefin polymer (component A) having a molecular weight of 500 to 1,000,000 containing a functional group, an organized layered clay mineral (component B) hydrogen-bonded to the functional group, A clay composite material comprising a polyolefin resin matrix (C component) in which an A component and a B component are dispersed is disclosed. This clay composite material is characterized in that the content of the functional group is 0.001 mmol / g or more and 0.45 mmol / g or less with respect to the component A. In this composite material, the layered clay mineral is well dispersed in the matrix, and the mechanical properties of the matrix are remarkably improved.

  However, although these methods can be applied to polystyrene and polypropylene, the effect of improving mechanical properties is not sufficient in polyethylene resins such as low density polyethylene and linear low density polyethylene. Furthermore, there is a problem that the good stretchability inherent to these polyethylene resins is impaired.

Non-Patent Document 1 discloses a polyethylene-clay nanocomposite composition obtained by melt-kneading linear low-density polyethylene, maleic acid-modified linear low-density polyethylene, and organic montmorillonite. About the said composition, it is supposed that the outstanding mechanical characteristic, rheological characteristic, and gas permeability will be acquired by using the organic-ized montmorillonite which has a specific alkyl group chain | strand.
However, when this nanocomposite composition is used for a film having a thickness of about 10 μm, such as a film for food packaging, the aggregate resulting from the composite material becomes visible and the transparency is lowered, and the food packaging The commercial value as a film is impaired. In addition, it has been clarified by the present inventors that characteristics suitable for shrink packaging, that is, excellent heat-fusibility and low-temperature shrinkage cannot be obtained sufficiently.

  As described above, while having high mechanical properties, it does not impair the good stretchability and transparency inherent in polyethylene, and has a particularly excellent heat-fusibility and low-temperature shrinkability required for film packaging. The thing is not obtained. In recent years, from the viewpoint of saving resources, there has been an increasing demand for thinner molded products, that is, higher strength, and it has good heat fusion properties and low-temperature shrinkability in terms of significantly increasing the speed, as exemplified by automatic film packaging machines. Has become essential. There is a strong demand for compositions and films that satisfy these requirements comprehensively.

Japanese Patent Laid-Open No. 10-30039 JP-T-2001-512773 Japanese Patent No. 3489411 S. Hotta, D.H. R. Paul, Nanocomposites formed from linear low density polytheylene and organoclays, Polymer 45 (2004) 7639-7654.

  An object of the present invention is to provide a polyethylene resin composition having excellent mechanical properties such as elastic modulus and having film and sheet properties such as transparency and stretchability. A further object of the present invention is to provide a polyethylene-based resin film that has high strength even in a thin wall, is excellent in heat-fusibility and low-temperature shrinkability, exhibits practically sufficient transparency and gloss, and has good shrink wrapping suitability. Is to provide.

  The inventors of the present invention have intensively studied to solve the above problems. As a result, a polyethylene resin composition in which the layered silicate is uniformly dispersed can be obtained by combining a low-melting linear low-density polyethylene, a modified low-density polyethylene that satisfies specific conditions, and an organically modified layered silicate. In addition, the polyethylene resin composition has been found to have significantly improved mechanical properties, particularly elastic modulus, and excellent shrink wrapping film properties without impairing the transparency and stretch processability inherent in polyethylene. The invention has been completed.

That is, the present invention is as follows.
(1). Linear low density polyethylene (A) having a melting point (T _m ) of 110 ° C. or less by differential scanning calorimetry 20 to 99.85% by weight; modified low density polyethylene (B) having a polar functional group in the molecule And a polyethylene-based resin composition comprising 0.1 to 40% by weight of an organized layered silicate (C) obtained by modifying a layered silicate with a cationic surfactant.
(2). The polyethylene type according to item (1), wherein the organic layered silicate (C) is obtained by organically modifying a synthetic fluorinated mica represented by the following formula (1) with an organic cationic surfactant. Resin composition.
_{NaMg 2.5 Si 4 O 10 (F} α OH (1-α)) 2 (0.8 ≦ α ≦ 1.0) (1)
(3). When the X-ray diffraction measurement of the organic layered silicate (C) is performed, the interlayer distance h0 calculated from the value of 2θ indicated by the main peak of the diffraction pattern in the range of 2θ = 0 to 10 ° using the formula (2) The polyethylene resin composition according to item (1) or (2), wherein is 19 to 35%.
h0 (Å) = 1.54 (Å) / 2sinθ (2)
(4). The melt viscosity parameter (V) represented by the formula (3) showing the relationship between the melt shear viscosity of the linear low density polyethylene (A) and the modified low density polyethylene (B) is 0.6 to 1.3. The polyethylene resin composition according to any one of items (1) to (3).
V = V _LDPE / V _LDPEm (3)
V _LDPE: melt shear viscosity of the linear low density polyethylene shear rate at 100sec ^-1 (A) V _LDPEm: melt shear viscosity of the modified shear rate at 100 sec ^-1 low density polyethylene (B) (5). The polyethylene resin composition according to any one of items (1) to (4), wherein a melting point (T _m ) by differential scanning calorimetry is 110 ° C. or less and a tensile elastic modulus is 150 MPa or more.
(6). When melt-kneading the linear low density polyethylene (A), the modified low density polyethylene (B), and the organically modified layered silicate (C) with a twin screw extruder, the organically modified layered silicate (C) is obtained by a side feed method. The manufacturing method of the polyethylene-type resin composition of any one of (1) term-(5) term including adding.
(7). A polyethylene resin single layer film comprising the polyethylene resin composition according to any one of items (1) to (5).
(8). A polyethylene-based resin multilayer film comprising one or more layers composed of a single layer of the polyethylene-based resin composition according to any one of items (1) to (5).
(9). A polyethylene-based resin multilayer film including one or more layers including the polyethylene-based resin composition according to any one of items (1) to (5) as one component.
(10). A stretched polyethylene resin film obtained by stretching the polyethylene resin film according to any one of Items (7) to (9).
(11). A polyethylene resin cross-linked stretched film obtained by cross-linking and stretching the polyethylene resin film according to any one of items (7) to (9).

  The polyethylene-based resin composition according to the present invention has a very high elastic modulus improving effect as compared with a polyolefin-based resin composition obtained by a conventional technique without impairing the elongation or transparency of the polyethylene-based film. . In addition, it has good heat-fusibility and shrinkage at low temperatures. Therefore, the thickness of the film can be reduced and the amount of filler added can be reduced, which is useful not only for various films but also for saving resources.

The present invention is described in detail below.
Examples of the linear low density polyethylene (A) in the present invention include ethylene homopolymers, ethylene and propylene, butene-1, pentene-1, 4-methyl-pentene-1, hexene-1, octene-1, and the like. Examples thereof include a copolymer with at least one monomer selected from α-olefins having 3 to 18 carbon atoms. The polymer may be polymerized with either a multi-site catalyst or a single-site catalyst, but a polymer polymerized with a single-site catalyst is more preferable because of its excellent transparency.

The melting point by differential scanning calorimetry (DSC) of linear low density polyethylene of the present invention (A) _{(T m)} is 110 ° C. or less. The melting point (T _m ) described here is a measurement of melting-crystallization-melting profile consisting of the following three steps using a differential scanning calorimeter Diamond DSC (trade name) manufactured by PerkinElmer Japan Co., Ltd. The peak temperature of the secondary melting curve in Step 3 was defined as the melting point (T _m ). When two or more melting peaks were observed, the lowest peak temperature having 20% or more of the total heat of fusion was defined as the melting point (T _m ).
Step 1: Hold at 30 ° C for 1 minute → Increase to 200 ° C at 10 ° C / minute (primary melting)
Step 2: Hold at 200 ° C for 1 minute → Decrease to 30 ° C at 10 ° C / min (crystallization)
Step 3: Hold at 30 ° C for 1 minute → Increase to 200 ° C at 10 ° C / min (secondary melting)

When the melting point (T _m ) is 110 ° C. or less, excellent heat-fusibility and low-temperature shrinkage necessary for films, particularly shrink wrapping films, can be obtained. That is, when the heat seal temperature and the shrink temperature are expanded or shifted to the low temperature side, the seal and shrink can be performed in a short time, and high-speed automatic continuous packaging can be handled. The melting point (T _m ) is more preferably 107 ° C. or lower, and further preferably 100 ° C. or lower, in order to obtain a tighter and more beautiful package while supporting continuous automatic packaging where the speed is increased. . These melting points are affected by the molecular weight of the polymer main chain, the molecular weight and branching degree of the side chain, and the molecular weight distribution.
Specific examples of the above-described linear low density polyethylene having a melting point (T _m ) of 110 ° C. or less include trade names, Sumikasen E FV101 (T _m = 107 ° C.), FV201 (T _m = 101 ° C.) manufactured by Sumitomo Chemical Co., Ltd. ), FV202 (T _m = 107 ° C.), manufactured by Mitsui Chemicals, trade name, Evolue SP0540 (T _m = 88 ° C.), manufactured by Ube Industries, trade name, Umerit 0540F (T _m = 87 ° C.), 1520F (T _m = 98 ° C.).

The modified low-density polyethylene (B) having a polar functional group in the molecule in the present invention is one in which a polar functional group is introduced into its side chain or main chain by modification of a low-density polyethylene resin. Examples of the polar functional group include a carboxylic acid group, an acid anhydride group, a hydroxyl group, a thiol group, a nitro group, an amide group, and an imide group.
The production method of the modified low density polyethylene (B) is not particularly limited, and there are a polymerization type in which the low density polyethylene is polymerized and then modified, or a method in which the polymer is modified when the high molecular weight polyethylene resin is decomposed. Of these, the polymerization type is preferred.

The content of the polar functional group contained in the modified low density polyethylene (B) is preferably 0.05 to 0.25 mmol / g with respect to the modified polyethylene. More preferably, it is the range of 0.08-0.2 mmol / g. When the polar functional group content is 0.05 mmol / g or more, intercalation of the organically modified layered silicate is likely to occur. Therefore, it is preferable because mechanical properties such as elastic modulus of the obtained polyethylene resin composition are improved. When the amount of the polar functional group is 0.25 mmol / g or less, intercalation occurs sufficiently and the compatibility with the low density polyethylene (A) as a matrix is high. For this reason, the dispersion of the organically modified layered silicate in the entire polyethylene resin composition is favorable, the agglomerates are hardly generated, and the transparency of the film is improved, which is preferable.
The modified low density polyethylene (B) that can be used in the present invention only needs to satisfy the above requirements. From the viewpoint of compatibility with the linear low density polyethylene resin (A), a modified linear low density polyethylene is preferred.

  Specific examples of the modified low density polyethylene (B) include, for example, Mitsui Chemicals, trade name, Admer LB548, modified low density polyethylene such as LF128, Mitsui DuPont Polychemicals, trade name, Fusabond E MB226D, Similarly, MB528D, MX110D, Mitsui Chemicals, trade name, Admer NB508, NF518, NF548, Crompton, trade name, Polybond 3109 modified linear low density polyethylene can be mentioned. Among these, Fusbond E MB226D and MB528D are also preferable. This is because the polar functional group amount is in a particularly suitable range, intercalation into the organically modified layered silicate is likely to occur, and the physical properties of the resulting polyethylene resin composition are further improved.

Examples of the layered silicate used to obtain the organically modified layered silicate (C) in the present invention include smectite clay minerals such as montmorillonite, saponite, hectorite, beidellite, stevensite, nontronite, vermiculite, and swelling. Sex mica etc. are mentioned. These layered silicates may be those obtained by purifying natural products or synthetic products synthesized by a known method such as a hydrothermal method. Among them, montmorillonite and swellable mica are highly effective in improving physical properties. Synthetic fluorinated mica with a particularly large aspect ratio can be oriented by secondary (molding) processing such as injection molding or film stretching after being uniformly dispersed in the composition of the present invention, resulting in a higher elastic modulus improving effect. Is obtained. Furthermore, it is preferable in that reorganization of the organically modified layered silicate at the time of secondary processing is easily suppressed, that is, generation of aggregates is easily suppressed even in a thin food packaging film.
Specific examples of the montmorillonite include, for example, Southern Clay, trade name, Cloisite Na, Kunimine Kogyo Co., Ltd., trade name, Kunipia RG, synthetic fluorinated mica, Cope Chemical Co., trade name, Somasif ME100, etc. Can be mentioned.

  These layered silicates have a continuous layer structure, and cations such as sodium ions, potassium ions, and lithium ions exist between the layers, and are hydrophilic. For this reason, polar solvents such as water and alcohol enter the layers and swell, and partly peel and disperse. Swelling refers to a state in which the interlayer distance is expanded by interposing a third substance between layers. Moreover, peeling dispersion | distribution refers to the state which the layer mutually peeled when swelling further progressed and the layered structure collapsed and was disperse | distributed finely.

  The layered silicate preferably has a cation exchange capacity (CEC) of 50 to 150 meq / 100 g. Thereby, the interlayer of the layered silicate can be greatly swollen. When the amount is less than 50 meq / 100 g, cation exchange with the cationic surfactant is not sufficiently performed, and it may be difficult to swell the layers of the layered silicate. If it exceeds 150 meq / 100 g, the bonding between the layers of the layered silicate becomes strong and it may be difficult to swell.

（化学式中、Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４はそれぞれ独立して水素、あるいはメチル、エチル、プロピル、ラウリル、オレイル、ステアリル等に代表される飽和あるいは不飽和炭化水素鎖である。該炭化水素鎖は直鎖であっても分岐構造を有していてもよい。また炭化水素鎖は、牛脂やヤシ油に代表されるような天然物に由来するものでもよい。また、Ｒ_１〜Ｒ_４の炭化水素鎖のうち少なくとも１つは、炭素数が１０以上であることが好ましい。最長の炭化水素鎖を構成する炭素数が１０未満であると、有機化層状珪酸塩（Ｃ）と直鎖状低密度ポリエチレン（Ａ）との親和性が不十分となり、十分な物性改良効果が得られない場合がある。Ｘ⁻はアニオンを示し、特に限定されないが、主に塩化物イオンや臭化物イオンなどのハロゲン化物イオンがこれに該当する。
カチオン系界面活性剤の具体例としては、例えば、ジメチルジステアリルアンモニウムブロミド（あるいはクロリド）、オクタデシルトリメチルアンモニウムブロミド（あるいはクロリド）などの４級アンモニウム塩、オクタデシルトリメチルアミンなどのアミン類などが挙げられる。Moreover, the cationic surfactant used for obtaining the organically modified layered silicate (C) in the present invention refers to a salt produced by the coordination of an organic substance component and a Lewis base. For example, an organic amine compound that generates a cation when dissolved in a quaternary ammonium salt or an acidic polar solvent corresponds to this, and has a structure represented by the following chemical formula (4).

(In the chemical formula, R ₁ , R ₂ , R ₃ and R ₄ are each independently hydrogen, or a saturated or unsaturated hydrocarbon chain represented by methyl, ethyl, propyl, lauryl, oleyl, stearyl, etc.) the hydrocarbon chain may have a branched structure may be linear. the hydrocarbon chain may be derived from a natural product such as represented by beef tallow and coconut oil. in addition, R ₁ ~ At least one of the hydrocarbon chains of R ₄ preferably has 10 or more carbon atoms, and when the carbon number constituting the longest hydrocarbon chain is less than 10, the organically modified layered silicate (C) and affinity with linear low density polyethylene (a) becomes insufficient, sufficient physical property improving effect can not be obtained .X ^- it represents an anion, is not particularly limited, mainly chloride ions and bromide Halogenation of ions, etc. Ion corresponds to this.
Specific examples of the cationic surfactant include quaternary ammonium salts such as dimethyl distearyl ammonium bromide (or chloride) and octadecyltrimethylammonium bromide (or chloride), and amines such as octadecyltrimethylamine.

The organically modified layered silicate (C) in the present invention is treated by treating the layered silicate with a cationic surfactant, and is exchanged with a cation existing between the layers and a cation of the cationic surfactant to be organicated. Is. The presence of organic cations between layers improves the affinity with organic solvents and organic substances. That is, while the layered silicate swells with a polar solvent such as water, the organically modified layered silicate has a property of swelling when an organic substance is taken in between the layers. Organized layered silicate easily peels and disperses in organic materials such as thermoplastic resins because of such properties.
There is no particular limitation on the method for synthesizing the organically modified layered silicate from the cationic surfactant and the layered silicate. In the case of using an amine compound, it is possible to use a method in which a hydrophilic solvent is acidified with hydrochloric acid or the like, the layered silicate is dispersed, and the amine compound is cationized and then ion exchange is performed.

In the present invention, in order for the polyethylene resin composition to obtain a high effect of improving physical properties, the interlayer distance h0 of the organically modified layered silicate (C) is preferably 19 to 35 mm. More preferably, it is 24 to 35 mm, and most preferably 30 to 35 mm.
H0 described here is powder X-ray diffraction measured using an X-ray diffractometer RINT2000 (trade name) manufactured by Rigaku Corporation with an acceleration voltage of 40 kV, an acceleration current of 200 mA, a scanning speed of 1 ° / min, and Cu Kα rays. From the 2θ value indicated by the main peak in the range of 2θ = 0 to 10 ° of the pattern, calculation is performed using Equation (2).
h0 (Å) = 1.54 (Å) / 2sinθ (2)
The value of h0 can be controlled by a combination of the hydrocarbon chain of the cationic surfactant described above and the cation exchange amount (CEC) of the layered silicate.

Specific examples of the organically modified layered silicate that satisfies this requirement include a product name, Cloisite 15A (h0 = 31.5Å) manufactured by Southern Clay, in which montmorillonite is modified with a dimethyldialkylammonium salt, and Cloisite 20A (h0 = 24. 2)), and the product name, Somasif MAE (h0 = 34.0Å) manufactured by Co-op Chemical Co., Ltd., which is obtained by modifying the synthetic fluorinated mica represented by the formula (1) with a dimethyldialkylammonium salt.
NaMg _2.5 Si ₄ O ₁₀ (F _α OH _(1-α) ) ₂ (0.8 ≦ α ≦ 1.0) (1)
In particular, this Somasif MAE (trade name) has a large aspect ratio, and a higher elastic modulus improving effect can be obtained by orientation by secondary (molding) processing after being uniformly dispersed in the composition of the present invention. Moreover, since it is easy to suppress the re-aggregation of the organic layered silicate during the secondary processing, it is particularly preferably used in the present invention.

The proportion of each component in the polyethylene resin composition of the present invention is 20 to 99.85 weights of linear low density polyethylene (A) having a melting point ( _Tm ) of 110 ° C. or less by differential scanning calorimetry (DSC). %, The modified low density polyethylene (B) having a polar functional group in the molecule is 0.05 to 40% by weight, and the organically modified layered silicate (C) obtained by modifying the layered silicate with a cationic surfactant is 0.1. -40% by weight. Preferably, the linear low density polyethylene (A) is 30 to 99.775% by weight, the modified low density polyethylene (B) is 0.075 to 35% by weight, and the organic layered silicate (C) is 0.15 to 0.15%. 35% by weight. More preferably, the linear low density polyethylene (A) is 40 to 99.7% by weight, the modified low density polyethylene (B) is 0.1 to 30% by weight, and the organically modified layered silicate (C) is 0.2. ~ 30% by weight.
If the ratio of the organic layered silicate (C) is less than 0.1% by weight, physical properties such as the elastic modulus of the polyethylene resin composition cannot be improved. On the other hand, if it exceeds 40% by weight, the melt viscosity of the polyethylene-based resin composition becomes too high, and the moldability may be impaired. Moreover, it is preferable that the ratio of the modified low density polyethylene (B) having a polar functional group in the molecule is 0.5 times or more by weight ratio with respect to the organically modified layered silicate (C). If it is 0.5 times or more, the modified low density polyethylene is easily intercalated between the layers of the organically modified layered silicate. This increases the interface between the layered silicate and the low-density polyethylene, and the effect of the layered silicate reinforcing the polyethylene resin increases.

  The polyethylene resin composition of the present invention may be prepared by mixing and dispersing linear low density polyethylene (A), modified low density polyethylene (B), and organically modified layered silicate (C) with a melt kneader. Examples of the melt-kneader include kneaders such as Banbury mixers and roll mixers, and twin-screw extruders (screw rotational speeds are in the same direction and different directions). The order of mixing may be the simultaneous mixing of the linear low density polyethylene (A), the modified low density polyethylene (B) having a polar functional group in the molecule, and the organically modified layered silicate (C). You may mix in order. When using a kneader, the modified low density polyethylene (B) and the organically modified layered silicate (C) are mixed and kneaded for about 5 to 10 minutes, and then the linear low density polyethylene (A) is added. A method of further mixing for about 5 to 10 minutes; or the modified low density polyethylene (B) and the organically modified layered silicate (C) are melt-kneaded into a master batch in advance, and then the linear low density polyethylene (A) and A mixing method in which, after mixing, melt kneading is preferred. When using an extruder, a mixture of linear low-density polyethylene (A), modified low-density polyethylene (B), and organically modified layered silicate (C) mixed in a dry state in a single-screw extruder is charged from the hopper. And a melt kneading method (top feed method). Kneading by a twin screw extruder that can enhance dispersibility by efficiently applying shear stress during kneading is more preferable. When using a twin screw extruder, the top feed method can also be used like a single screw extruder. Further, after mixing the linear low density polyethylene (A) and the modified low density polyethylene (B), adding them from a hopper and melt-kneading them, the organic layered silicate (C ) And then melt-kneading (side feed method) may be employed. By such a method, it is possible to obtain a high mechanical property improving effect such as an elastic modulus by minimizing breakage of the organically modified layered silicate due to shear stress.

In the present invention, the value of the melt viscosity parameter (V) indicating the relationship between the melt shear viscosity of the linear low density polyethylene (A) and the melt shear viscosity of the modified low density polyethylene (B) is 0.3 to 1. The range of 3 is preferable, and the range of 0.6 to 1.2 is more preferable.
The melt viscosity parameter (V) described here is calculated as follows. Capillograph 1C (trade name) manufactured by Toyo Seiki Seisakusho Co., Ltd. is attached with a capillary having a length of 10 mm and a nozzle diameter of 1.0 mm, the barrel temperature is set to 190 ° C., linear low density polyethylene (A) Alternatively, the pellets of the modified low density polyethylene (B) are divided into several times and filled in the barrel while being sufficiently evacuated to melt. The piston speed is increased stepwise to 0.5, 1, 2, 5, 10, 20, 50, 100 mm / min and extruded from the capillary while changing the shear rate, and the apparent melt shear viscosity at each shear rate is calculated. . From the curve of the resulting melt shear viscosity, melt shear viscosity of the apparent apparent melt shear viscosity _{V LDPE} linear low density polyethylene shear rate at 100 sec ^-1 (A), modified low-density polyethylene (B) _{V LDPEm} V is obtained from the following equation (3).
V = V _LDPE / V _LDPEm (3)

When the melt viscosity parameter (V) is 0.3 to 1.3, the compatibility of the linear low density polyethylene (A) and the modified low density polyethylene (B) is sufficient, and the modified low density polyethylene (B ) Is well dispersed, and the organically modified layered silicate having an affinity for the modified low density polyethylene (B) is less likely to aggregate. As a result, the physical properties of the molded product are uniform, and even in the case of a food packaging film having a thickness of about 10 micrometers, the aggregates are hardly visible and the commercial value is not impaired.
The melt viscosity parameter can be within the preferable range of the present invention by selecting each resin so that the melt shear viscosity values of the linear low density polyethylene (A) and the modified low density polyethylene (B) are close to each other. Is possible.

  In the polyethylene resin composition of the present invention, an antioxidant, an ultraviolet absorber, a heat stabilizer, and a light stabilizer, which are usually used in the art, in an amount that does not adversely affect the desired physical properties of the resin composition. Various additives such as an agent, a flame retardant, a plasticizer, a nucleating agent, a colorant, a lubricant, and a surface gloss improving agent can be added.

  The polyethylene resin composition in the present invention is formed into a film or sheet by extrusion molding such as water-cooled or air-cooled inflation molding, simultaneous biaxial stretching, sequential biaxial stretching, T-die extrusion molding, extrusion lamination molding, or the like. It is possible. In addition, it can also be used for molded products by injection molding, blow molding, etc., bead foam molded products by in-mold foaming, and extrusion foam molded products using chemical foaming agents or physical foaming agents.

  In order to further enhance the improvement effect such as the elastic modulus of a molded article using the polyethylene resin composition of the present invention, the resin composition is oriented in the molding process, and the organically modified layered silicic acid is contained in the resin composition. It is preferable to arrange the salts. In particular, when stretching is performed in film forming, the degree of orientation of the organically modified layered silicate is increased, and the resulting elastic modulus of the molded product is further increased. Also, in the injection molding, when the resin composition is filled into the mold as slowly as possible so as not to clog in the cavity and the mold, the resin composition is cooled and fixed at the contact surface with the mold, A fountain-like resin flow called a fountain flow that flows while the resin composition is stretched between the front ends is generated. Therefore, the degree of orientation of the organically modified layered silicate in the surface layer of the obtained molded product is increased, and a high elastic modulus improving effect can be obtained.

The melting point (T _m ) by differential scanning calorimetry (DSC) of the polyethylene resin composition in the present invention is 110 ° C. or less. The tensile elastic modulus is preferably 150 MPa or more.
The tensile elastic modulus described here was obtained by pulling a dumbbell test piece (JIS K7113 type 2) of a polyethylene resin composition at a test speed of 5 mm / min using an autograph AG5000D (trade name) manufactured by Shimadzu Corporation. It is calculated from the initial slope (less than 1% strain rate) of the obtained stress-strain curve diagram. A dumbbell test piece (JIS K7112 type) used for this tensile test was obtained by injecting a dry pellet of the polyethylene resin composition of the present invention at 190 ° C. with a KLOCKNER F85 (trade name) injection molding machine manufactured by Klockner Ferromatic Desma GmbH. It is obtained by molding at a pressure of 127.1 MPa, a holding pressure of 101.2 MPa, a holding time of 4 seconds, and a cooling time of 30 seconds.

In order to increase the tensile elastic modulus to 150 MPa or more, the organic compound having a large aspect ratio (L / D) obtained by organic modification of the synthetic fluorinated mica suitably used in the present invention with an organic cationic surfactant is used. By using a layered silicate; and by side-feeding the organically modified layered silicate, the decrease in L due to shear fracture is minimized, while promoting the exfoliation of the organicated layered silicate and increasing dispersibility This can be achieved by increasing L / D as much as possible.
When the polyethylene-based resin composition satisfying the above requirements of the present invention is formed into a film, it has excellent heat-fusibility, low-temperature shrinkage and rigidity such as elasticity and stiffness.

  The polyethylene-based resin film in the present invention is a single-layer film comprising the polyethylene-based resin composition of the present invention; a multilayer film in which the polyethylene-based resin of the present invention forms a single layer, and at least one layer is included. The polyethylene-based resin composition of the present invention constitutes one component of the layer, and at least one of the layers is a multilayer film containing one or more layers.

  The polyolefin-based resin film in the present invention is stretched by a roll stretching method, a tenter stretching method, a bubble inflation method (including a double bubble method), etc., in order to further enhance the effect of improving the elastic modulus and the like by applying orientation as described above. It is preferable to do this. Although there are various stretching methods, a method of forming a film by the simultaneous biaxial stretching method is preferable from the viewpoint of stretchability and other rationality. Further, the stretching is preferably performed at least in one direction at an area stretching ratio of 3 to 50 times, more preferably 4 to 40 times, and is appropriately selected depending on the application.

  Furthermore, at least one layer of the film of the present invention may be crosslinked. When the degree of cross-linking in the thickness direction is almost uniform, when a specific layer is mainly cross-linked, when the degree of cross-linking gradually changes from the surface layer to the thickness direction, both surface layers are mainly cross-linked and appropriately in the thickness direction Any of cases having a distribution may be used. This cross-linking treatment is performed before or after the stretched film is formed by single-sided or double-sided irradiation with an electron beam (for example, energy of 50 to 1000 kV), ultraviolet rays, X-rays, α-rays, and γ-rays, or in the thickness direction A method of performing irradiation such that a distribution of cross-linking is generated; or a method of performing a heat treatment after addition of peroxide or the like (in some cases, a cross-linking aid may be used in a specific layer and a cross-linking retarder may be used in a specific layer); or A combination of both methods; or other known methods may be used for the modification treatment. Preferably, a method using an electron beam (for example, by controlling the transmission depth to a predetermined level with an energy of 50 to 1000 kV) may be clean. The cross-linking treatment can improve heat-fusibility, heat resistance, stretching film formation stability (suppression of necking, uniformity of thickness, improvement of stretching ratio, expansion of stretching temperature condition range, etc.), if necessary Used.

Examples of suitable configurations of the multilayer stretched film in the present invention include, for example, 10 to 60% by weight of both surface layers made of an ethylene-vinyl acetate copolymer as a thickness ratio of each layer in all layers, and the polyethylene resin of the present invention. Three layers (surface layer) in which both intermediate layers composed of the composition and ethylene-vinyl acetate copolymer are 15 to 80% by weight, and the core layer composed of polypropylene and polypropylene / polybutene-1 copolymer is 10 to 60% by weight. A multilayer stretched film composed of (intermediate layer-core layer-intermediate layer-surface layer).
Moreover, the polyethylene-type resin composition of this invention which comprises the intermediate | middle layer of this multilayer stretched film is 20-99.85 weight% of linear low density polyethylene, 0.05-40 of maleic acid modified linear polyethylene, for example. It can be adjusted at a ratio of wt%, organic layered silicate 0.1-40 wt%. The proportion of the polyethylene resin composition of the present invention in the intermediate layer is preferably 10 to 50% by weight.

Examples of a suitable composition of the crosslinked multilayer stretched film in the present invention include, for example, 5 to 40% by weight of both surface layers composed of low-density polyethylene and linear low-density polyethylene as the thickness ratio of each layer occupying in all layers. Crosslinked multilayer stretched film comprising a core layer composed of a polyethylene resin composition of 60 to 95% by weight and two types and three layers (surface layer-core layer-surface layer); or low density polyethylene and linear low Both surface layers made of high-density polyethylene are 5 to 40% by weight, both intermediate layers made of the polyethylene resin composition of the present invention are 20 to 50% by weight, and the core layer made of low-density polyethylene and linear low-density polyethylene is 10 It is a cross-linked multilayer stretched film composed of 3 types and 5 layers (surface layer-intermediate layer-core layer-intermediate layer-surface layer) of -75 wt%.
In addition, the thickness of the film in the present invention is preferably 100 μm or less, more preferably in order to obtain a high improvement effect such as elastic modulus while maintaining high transparency and excellent heat-fusibility and low-temperature shrinkage. Is 20 μm or less, more preferably 10 μm or less.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.
The measurement and calculation and evaluation methods of the indicators and physical properties used in the present invention are as follows.

(1) Melting point: T _m
Using a differential scanning calorimeter Diamond DSC (trade name) manufactured by PerkinElmer Japan, Inc., the melting-crystallization-melting profile consisting of the following three steps was measured, and the peak of the secondary melting curve in step 3 The temperature was defined as the melting point (T _m ) (unit: ° C.). When two or more melting peaks were observed, the lowest peak temperature having 20% or more of the total heat of fusion was defined as the melting point (T _m ).
Step 1: Hold at 30 ° C for 1 minute → Increase to 200 ° C at 10 ° C / minute (primary melting)
Step 2: Hold at 200 ° C for 1 minute → Decrease to 30 ° C at 10 ° C / min (crystallization)
Step 3: Hold at 30 ° C for 1 minute → Increase to 200 ° C at 10 ° C / min (secondary melting)

(2) X-ray diffraction measurement of organic layered silicate Using an X-ray diffractometer RINT2000 (trade name) manufactured by Rigaku Corporation, acceleration voltage 40 kV, acceleration current 200 mA, scanning speed 1 ° / min, Cu Kα ray A powder X-ray diffraction pattern was obtained by powder X-ray diffraction. Based on this, ho (Å) was calculated using the above formula (2).

(3) Melt viscosity parameter: V
A capillary having a length of 10 mm and a nozzle diameter of 1.0 mm was attached to the barrel tip of Capillograph 1C (trade name) manufactured by Toyo Seiki Seisakusho, and the barrel temperature was set to 190 ° C. The pellets of linear low-density polyethylene (A) or modified low-density polyethylene (B) were divided into several times and filled in a barrel while being sufficiently deflated. The piston speed was increased stepwise to 0.5, 1, 2, 5, 10, 20, 50, 100 mm / min and extruded from the capillary while changing the shear rate, and the apparent melt shear viscosity at each shear rate was calculated. . From the obtained curve of the melt shear viscosity, the apparent melt shear viscosity V _{LDPE of} the linear low density polyethylene (A) at a shear rate of 100 sec ^{−1 and} the apparent melt shear viscosity V _{LDPEm of the} modified low density polyethylene (B) are _shown. V was calculated from V = V _LDPE / V _LDPEm .

(4) Tensile modulus and relative tensile modulus of polyethylene resin composition Using autograph AG5000D (trade name) manufactured by Shimadzu Corporation, dumbbell test piece (JIS K7113 type 2) of polyethylene resin composition Was pulled at a test speed of 5 mm / min to obtain a stress-strain curve diagram. The tensile modulus E (MPa) was calculated from the initial slope (less than 1% strain rate) of the stress-strain curve diagram. The tensile modulus E ₀ (MPa) of an injection-molded product molded only with the linear low-density polyethylene resin (A) used for the polyethylene resin composition was calculated in the same manner. And the value E / E ₀ obtained by dividing the E ₀ and E relative tensile modulus.

(5) Tensile Breaking Elongation of Polyethylene Resin Composition Using the same dumbbell test piece as the above tensile modulus, the tensile breaking elongation (%) was calculated from the breaking point when pulled at a test speed of 50 mm / min.
(6) Evaluation of Aggregate of Film A single cast film (thickness of about 100 μm) of the polyethylene resin composition was produced with a single screw extruder equipped with a T die, and the obtained film was visually evaluated as follows.
◎: Agglomerates are not confirmed at all and transparency is also good. ○: Some aggregates are present, but transparency is good. Δ: There are many aggregates and there is a problem with transparency. There are so many things that film formation is difficult

(7) Evaluation of tensile elastic modulus improvement effect of multilayer stretched film and crosslinked multilayer stretched film From a multilayer stretched film and a crosslinked multilayer stretched film comprising the polyethylene resin composition of the present invention as a constituent component, a 10 mm wide × 150 mm long strip Were cut out in the MD direction (film extrusion direction) and TD direction (direction perpendicular to the film extrusion direction), respectively, to obtain test pieces. Using an autograph AG-IS (trade name) manufactured by Shimadzu Corporation, the test piece was pulled at a chuck distance of 100 mm and a test speed of 5 mm / min to obtain a stress-strain curve diagram. Stress - than the slope of the initial distortion diagram (distortion less than 1%), the extrusion direction (MD direction) of the film, tensile modulus _M MD in the width direction (TD _direction), M TD (MPa), respectively n = 5 The average was calculated. Further, M _MD and M _TD were averaged to obtain a tensile elastic modulus M (MPa). In the same manner, the tensile elastic modulus M ₀ (MPa) of the multilayer stretched film using only the linear low-density polyethylene resin (A) used in the polyethylene resin composition instead of the polyethylene resin composition is determined. It was measured. The value M / M ₀ obtained by dividing the M ₀ to M as the relative tensile modulus was evaluated tensile modulus improving effect as follows.
A: The tensile modulus improvement effect is very high, and it can cope with 30% thinning (relative tensile modulus 1.3 or more)
○: High tensile modulus improvement effect (relative tensile modulus 1.1 or more and less than 1.3)
Δ: Low tensile modulus improvement effect (relative tensile modulus 1.0 to less than 1.1)
X: Tensile modulus improvement effect is not recognized (relative tensile modulus less than 1.0)

(8) Transparency Evaluation of Multilayer Stretched Film and Crosslinked Multilayer Stretched Film Using Nippon Denshoku Co., Ltd., trade name, NDH-300A, at room temperature of 27 ° C., according to ASTM-D-1003, the multilayer stretched film and crosslink of the present invention The haze of the multilayer stretched film was measured.
A: Visibility of contents is good (haze is 2.5 or less)
○: The contents are easily visible (haze is more than 2.5 and 5.0 or less)
Δ: Difficult to see contents (haze is over 5.0)

(9) Evaluation of heat-fusibility and low-temperature shrinkage of multilayer stretched film and multilayer cross-linked stretched film General commercial PP tray with a 100 g metal plate attached to the bottom inside (approximate dimensions: length 150 mm, width 115 mm, high The film was folded into a cylindrical shape along the vertical direction of 23 mm). Wrap the tray so that about half the area overlaps at the bottom of the tray without overlapping both ends of this film, and then do not fold along the lateral direction of the tray and do not bump both ends of the remaining film And folded at the bottom of the tray. At this time, three or five overlapping portions are formed at the bottom of the tray. The tray thus prepared was placed on a hot plate adjusted to 130 ° C. for 2 seconds to perform bottom sealing. Thereafter, the film was shrunk by passing through a hot air heating type tunnel at 90 to 110 ° C. in about 1 second, and the finished state was evaluated according to the following criteria.
◎: Good seal state (does not peel even if the end of the seal is pulled lightly) and good shrinkage over the entire range of 90 to 110 ° C ○: Good seal state but slightly insufficient shrinkage △: Partially sealed Not contracted, insufficient shrinkage ×: Not sealed at the bottom

(10) Overall evaluation of multilayer stretched film A: Elasticity improvement effect, transparency, heat-fusibility / cold shrinkage, all are A,
Level that can be suitably used as a packaging film ○: All are ◎ or ○, practical level as packaging film △: There is a level that is difficult to use as packaging film ×: There is ×, as packaging film Not practical

(11) Bareness and stiffness evaluation of multilayer cross-linked stretched film The film was fixed with double-sided tape so that there was no slack at the edge of a wooden frame with an outer dimension of 180 mm x 180 mm. Next, in this state, the film was shrunk by passing through a hot air tunnel at 90 ° C. for 3 seconds, and left at room temperature (about 23 ° C.) for about 3 minutes. Thereafter, the center of the film was pulled out about 10 mm vertically with a metal rod having a diameter of 15 mmφ and a hemispherical tip. One minute later, the surface of the film was observed and evaluated according to the following criteria.
◎: Sufficient elasticity, no slack, wrinkles or local dents ○: Elasticity, almost no slack, wrinkles or local dents △: No elasticity, slacks, wrinkles or local dents ×: There is no elasticity, there is clearly slack, wrinkles, and local dents

(12) Overall evaluation of multilayer cross-linked stretched film ◎: Elasticity improvement effect, elasticity, transparency, heat-fusibility / cold shrinkage,
All are ◎ and can be used suitably as packaging films ○: All are ◎ or ○, practical level as packaging film △: There is a level that is difficult to use as packaging film ×: × Yes, not practical level as packaging film

[Example 1]
Metallocene linear low density polyethylene (“Evolue SP0540” (trade name), melting point 88 ° C.) 90.0% by weight as linear low density polyethylene, maleic acid modified straight as modified low density polyethylene A linear low density polyethylene ("Fusabondo E MB226D" (trade name) manufactured by Mitsui DuPont Polychemical Co., Ltd., name of polar functional group = 0.09 mmol / g) of 5.0% by weight was twin screw extruder (Nippon Steel Works ( It was put in from a hopper of TEX30α (trade name) manufactured by Co., Ltd. and melt kneaded at a barrel temperature of 150 to 200 ° C. and a screw rotation speed of 300 rpm. Next, 5.0% by weight of dimethyldialkylammonium montmorillonite (“Cloisite 15A” (trade name): h0 = 31.5 mm) manufactured by Southern Clay Product, Inc.) is added as an organic layered silicate from a side feeder provided in the middle of the extruder. Then, further kneading was performed (side feed method). A strand was extruded from a multi-nozzle die attached to the tip of the extruder, and cut after cooling in a cold water bath. Then, it dried at 80 degreeC for 24 hours or more, and obtained the pellet of the polyethylene-type resin composition. The obtained pellets were measured for melting point (T _m ). Also, molding was performed with a KLOCKNER F85 (trade name) injection molding machine at 190 ° C., injection pressure 127.1 MPa, holding pressure 101.2 MPa, holding time 4 seconds, and cooling time 30 seconds to obtain a JIS K7113 type 2 test piece. It was. Table 1 shows the melting point of the polyethylene resin composition and the evaluation results of tensile properties using the test piece.

[Example 2]
A polyethylene resin under the same conditions as in Example 1 except that 83.4% by weight of linear low density polyethylene, 8.3% by weight of modified low density polyethylene, and 8.3% by weight of organic layered silicate were used. Composition pellets and specimens were obtained. Table 1 shows the melting point of the obtained polyethylene resin composition and the evaluation results of the tensile properties using the test piece.

[Example 3]
Polyethylene resin composition under the same conditions as in Example 2 except that synthetic fluorinated mica (“Somasif MAE” (trade name): h0 = 34.0 mm) manufactured by Corp Chemical Co., Ltd. was used as the organic layered silicate. Product pellets and specimens were obtained. Table 1 shows the melting point of the obtained polyethylene resin composition and the evaluation results of the tensile properties using the test piece.

[Example 4]
The organic resin layered silicate was mixed with linear low density polyethylene and modified low density polyethylene and charged into the extruder from the hopper (top feed method). A pellet and a test piece were obtained. Table 1 shows the melting point of the obtained polyethylene resin composition and the evaluation results of the tensile properties using the test piece.

[Example 5]
Polyethylene resin composition under the same conditions as in Example 4 except that dimethyldialkylammonium montmorillonite (“Cloisite 20A” (trade name): h0 = 24.2 製 manufactured by Southern Clay Product) was used as the organic layered silicate. Product pellets and specimens were obtained. Table 1 shows the melting point of the obtained polyethylene resin composition and the evaluation results of the tensile properties using the test piece.

[Example 6]
A pellet of a polyethylene resin composition and a test piece were obtained under the same conditions as in Example 5 except that the organically modified layered silicate was side-fed. Table 1 shows the melting point of the obtained polyethylene resin composition and the evaluation results of the tensile properties using the test piece.

[Example 7]
A pellet of a polyethylene resin composition and a test piece were obtained under the same conditions as in Example 3 except that the organic layered silicate was top-fed. Table 1 shows the melting point of the obtained polyethylene resin composition and the evaluation results of the tensile properties using the test piece.

[Example 8]
Example except that maleic acid-modified linear low-density polyethylene (“Fusabondo MB528D” (trade name), polar functional group amount = 0.13 mmol / g, manufactured by Mitsui DuPont Polychemical Co., Ltd.) was used as the modified low-density polyethylene. Under the same conditions as in No. 3, pellets of a polyethylene resin composition and test pieces were obtained. Table 1 shows the melting point of the obtained polyethylene resin composition and the evaluation results of the tensile properties using the test piece.

[Example 9]
Polyethylene resin composition under the same conditions as in Example 4 except that dimethyldialkylammonium montmorillonite (“Cloisite 25A” (trade name): h0 = 18.6 製 manufactured by Southern Clay Product) was used as the organic layered silicate. Product pellets and specimens were obtained. Table 1 shows the melting point of the obtained polyethylene resin composition and the evaluation results of the tensile properties using the test piece.

[Example 10]
The same conditions as in Example 3 were used except that metallocene linear low density polyethylene ("Umerit 1520F" (trade name), melting point 98 ° C, manufactured by Ube Maruzen Polyethylene Co., Ltd.) was used as the linear low density polyethylene. Polyethylene resin composition pellets and test pieces were obtained. Table 1 shows the melting point of the obtained polyethylene resin composition and the evaluation results of the tensile properties using the test piece.

[Example 11]
The same conditions as in Example 3 were used except that metallocene linear low density polyethylene (“Sumikasen E FV101” (trade name), melting point 107 ° C., manufactured by Sumitomo Chemical Co., Ltd.) was used as the linear low density polyethylene. Polyethylene resin composition pellets and test pieces were obtained. Table 1 shows the melting point of the obtained polyethylene resin composition and the evaluation results of the tensile properties using the test piece.

[Example 12]
The same conditions as in Example 3 were used except that metallocene linear low density polyethylene (“Sumikasen E FV201” (trade name), melting point 101 ° C., manufactured by Sumitomo Chemical Co., Ltd.) was used as the linear low density polyethylene. Polyethylene resin composition pellets and test pieces were obtained. Table 1 shows the melting point of the obtained polyethylene resin composition and the evaluation results of the tensile properties using the test piece.

[Comparative Example 1]
An injection-molded article test piece of metallocene linear low-density polyethylene (“Evolue SP0540” (trade name), melting point 88 ° C., manufactured by Prime Polymer Co., Ltd.) was obtained under the same conditions as in Example 1. Table 1 shows the evaluation results of the tensile properties using the obtained test pieces.

[Comparative Example 2]
An injection molded product test piece of linear low density polyethylene (“Dowlex 2032” (trade name), melting point 122 ° C., manufactured by Dow Chemical Co., Ltd.) was obtained under the same conditions as in Example 1. Table 1 shows the evaluation results of the tensile properties using the obtained test pieces.

[Comparative Example 3]
A polyethylene resin composition pellet and a test piece were prepared under the same conditions as in Example 9, except that (Dow Chemical's “Dowlex 2032” (trade name), melting point 122 ° C.) was used as the linear low density polyethylene. Obtained. Table 1 shows the melting point of the obtained polyethylene resin composition and the evaluation results of the tensile properties using the test piece.

[Comparative Example 4]
An injection molded product test piece of metallocene linear low density polyethylene ("Umerit 1520F" (trade name), melting point 98 ° C, manufactured by Ube Maruzen Polyethylene Co., Ltd.) was obtained under the same conditions as in Example 1. Table 1 shows the evaluation results of the tensile properties using the obtained test pieces.

[Comparative Example 5]
An injection molded product test piece of metallocene linear low density polyethylene (“Sumikasen E FV101” (trade name), melting point 107 ° C., manufactured by Sumitomo Chemical Co., Ltd.) was obtained under the same conditions as in Example 1. Table 1 shows the evaluation results of the tensile properties using the obtained test pieces.

[Comparative Example 6]
An injection-molded product test piece of metallocene linear low-density polyethylene (“Sumikasen E FV201” (trade name), melting point 101 ° C., manufactured by Sumitomo Chemical Co., Ltd.) was obtained under the same conditions as in Example 1. Table 1 shows the evaluation results of the tensile properties using the obtained test pieces.
As can be seen from the results in Table 1, the polyethylene-based resin composition of the present invention is very high without substantially changing the melting point of the linear low-density polyethylene (A) used and without greatly reducing the elongation. The effect of improving the tensile modulus is obtained.

[Example 13]
A single-screw extruder equipped with the polyolefin resin composition obtained in Example 8 (melt viscosity parameter of linear low-density polyethylene and modified low-density polyethylene: V = 0.9) and a T-die at the tip. It was used and melt kneaded at a barrel temperature of 150 to 200 ° C. and a screw rotation speed of 50 rpm to obtain a cast film having a thickness of about 100 μm. Table 2 shows the aggregate evaluation results of the obtained film.

[Example 14]
Cast under the same conditions as in Example 13, except that the polyolefin resin composition obtained in Example 3 (melt viscosity parameter of linear low density polyethylene and modified low density polyethylene: V = 0.4) was used. A film was obtained. Table 2 shows the aggregate evaluation results of the obtained film.

[Example 15]
Cast under the same conditions as in Example 13 except that the polyolefin-based resin composition obtained in Example 10 (melt viscosity parameter of linear low-density polyethylene and modified low-density polyethylene: V = 0.6) was used. A film was obtained. Table 2 shows the aggregate evaluation results of the obtained film.

[Example 16]
Cast under the same conditions as in Example 13 except that the polyolefin resin composition obtained in Example 11 (melt viscosity parameter of linear low-density polyethylene and modified low-density polyethylene: V = 0.8) was used. A film was obtained. Table 2 shows the aggregate evaluation results of the obtained film.

[Example 17]
Cast under the same conditions as in Example 13 except that the polyolefin resin composition obtained in Example 12 (melt viscosity parameter of linear low density polyethylene and modified low density polyethylene: V = 0.6) was used. A film was obtained. Table 2 shows the aggregate evaluation results of the obtained film.

[Comparative Example 7]
As a linear low density polyethylene (“Dowlex 2032” (trade name) manufactured by Dow Chemical, melting point: 122 ° C.), a dimethyldialkylammonium montmorillonite (“Cloite 20A” (trade name) manufactured by Southern Clay Products) as an organic layered silicate: Except that h0 = 24.2２４ was used, pellets of a polyethylene resin composition were obtained under the same conditions as in Example 8 (melt viscosity parameters of linear low-density polyethylene and modified low-density polyethylene: V = 16 .4). Using this pellet, a cast film was obtained under the same conditions as in Example 13. Table 2 shows the aggregate evaluation results of the obtained film.
As is clear from Table 2, the polyethylene resin composition of the present invention can suppress the generation of aggregates when formed into a film, and good transparency is obtained.

[Examples 18 to 20, Comparative Example 8]
With the composition shown in Table 3, three extruders were used, and a five-layer tube consisting of both surface layers, core layers, and both intermediate layers was melt-extruded from three types of five-layer annular dies, and a water-cooled ring was used. It was used and rapidly cooled to obtain an unstretched tube (parison). Each extrusion amount was adjusted so that each layer had a predetermined ratio, and the layer configuration was confirmed by cross-sectional observation. The temperature setting of the extruder has six temperature adjustment zones in the longitudinal direction. For the surface layer and intermediate layer extruders in order from the resin supply hopper, 180 ° C, 200 ° C, 210 ° C, 220 ° C, 230 ° C, 230 ° C. The core layer was formed at 200 ° C., 200 ° C., 200 ° C., 190 ° C., 190 ° C., and 190 ° C.

The obtained unstretched tube was sent to the stretched part and heated by hot air heating using an infrared heater. The zone was stretched in the longitudinal direction, and the stretch ratio was adjusted by the speed ratio of the heated pinch roller and the winder. While cooling with an air cooling ring, air was injected to form bubbles and stretched at 55 ° C. Then, a slight heat set was performed at 50 ° C. as a folding double film in the deflator part, and the film was wound up by a winder. The draw ratio in the transverse direction was adjusted by the width of the film and the width of the parison at this time. About the draw ratio, the amount of extrusion was adjusted so that it might become predetermined | prescribed thickness using the magnification which a bubble is most stable. Using a slitter, slitting was performed while peeling the double film original into a single film, and multilayer stretched films of Examples 18 to 20 and Comparative Example 8 were obtained. Table 3 shows the tensile elastic modulus improvement effect, transparency, heat-fusibility, and low-temperature shrinkage evaluation results of the obtained film.
As can be seen from the results in Table 3, the multilayer stretched film using the polyethylene resin composition of the present invention is a film having both a high tensile elastic modulus improving effect and transparency, excellent heat-fusibility and low-temperature shrinkage. .

[Examples 21 to 23, Comparative Examples 9 to 12]
With the composition shown in Table 4, three extruders were used, a three-layer tube consisting of two surface layers and a core layer was melt-extruded from two types of three-layer annular dies, and rapidly cooled using a water-cooled ring Thus, an unstretched tube (parison) having a thickness of about 560 μm was obtained. Each extrusion amount was adjusted so that each layer had a predetermined ratio, and the layer configuration was confirmed by cross-sectional observation. The temperature setting of the extruder has six temperature adjustment zones in the longitudinal direction, and was performed at 180 ° C., 200 ° C., 220 ° C., 230 ° C., 245 ° C., and 245 ° C. in order from the resin supply hopper. The resulting unstretched tube having a thickness of about 560 μm was subjected to a crosslinking treatment by irradiating an electron beam of 500 kV with 85 kGy. Subsequently, the unstretched tube is heated to 140 ° C. by radiant heating with an infrastructure heater, and the width direction (machine) is injected by injecting air into the tube approximately 8 to 9 times in the flow direction by the speed ratio between the two nip rolls. The film was stretched about 6 to 7 times in the direction perpendicular to the flow direction of the water and cooled by applying cold air to the bubble maximum diameter portion from the air ring. Thereafter, the film was folded and wound up with a winder while slitting both ends into a single film to obtain a film original having a thickness of about 9 to 11 μm. Table 4 shows the tensile modulus improvement effect, transparency, heat-fusibility and low-temperature shrinkage evaluation results of the obtained film.
As can be seen from the results in Table 4, the cross-linked multilayer stretched film using the polyethylene resin composition of the present invention has a high tensile elastic modulus improving effect, and can maintain sufficient elasticity and stiffness even when it is thinned. It is a film that combines transparency, excellent heat-fusibility, and low-temperature shrinkage.

  The polyethylene resin composition of the present invention has excellent mechanical properties, transparency, stretch processability, heat-fusibility, and low-temperature shrinkage, and is suitable as a shrink wrapping film.

Claims (11)

Linear low density polyethylene (A) having a melting point (T _m ) of 110 ° C. or less by differential scanning calorimetry 20 to 99.85% by weight; modified low density polyethylene (B) having a polar functional group in the molecule And a polyethylene-based resin composition comprising 0.1 to 40% by weight of an organized layered silicate (C) obtained by modifying a layered silicate with a cationic surfactant. The polyethylene resin composition according to claim 1, wherein the organically modified layered silicate (C) is obtained by organically modifying a synthetic fluorinated mica represented by the following formula (1) with an organic cationic surfactant. object.
NaMg _2.5 Si ₄ O ₁₀ (F _α OH _(1-α) ) ₂ (0.8 ≦ α ≦ 1.0) (1) When the X-ray diffraction measurement of the organic layered silicate (C) is performed, the interlayer distance h0 calculated from the value of 2θ indicated by the main peak of the diffraction pattern in the range of 2θ = 0 to 10 ° using the formula (2) The polyethylene-based resin composition according to claim 1, wherein is 19 to 35%.
h0 (Å) = 1.54 (Å) / 2sinθ (2) The melt viscosity parameter (V) represented by the formula (3) showing the relationship between the melt shear viscosity of the linear low density polyethylene (A) and the modified low density polyethylene (B) is 0.3 to 1.3. The polyethylene resin composition according to any one of claims 1 to 3.
V = V _LDPE / V _LDPEm (3)
V _LDPE: melt shear viscosity of the linear low density polyethylene shear rate at 100sec ^-1 (A) V _LDPEm: melt shear viscosity of the modified shear rate at 100 sec ^-1 low density polyethylene (B) The polyethylene-type resin composition of any one of Claims 1-4 whose melting | fusing point ( _Tm ) by differential scanning calorimetry is 110 degrees C or less, and whose tensile elasticity modulus is 150 Mpa or more.   When melt-kneading the linear low density polyethylene (A), the modified low density polyethylene (B), and the organically modified layered silicate (C) with a twin screw extruder, the organically modified layered silicate (C) is obtained by a side feed method. The manufacturing method of the polyethylene-type resin composition of any one of Claims 1-5 including adding.   The polyethylene-type resin single layer film which consists of a polyethylene-type resin composition of any one of Claims 1-5.   A polyethylene-based resin multilayer film comprising at least one layer composed of the polyethylene-based resin composition according to any one of claims 1 to 5.   The polyethylene-type resin multilayer film containing 1 or more layers which contain the polyethylene-type resin composition of any one of Claims 1-5 as one component.   The polyethylene-type resin stretched film obtained by extending | stretching the polyethylene-type resin film of any one of Claims 7-9.   A polyethylene resin cross-linked stretched film obtained by cross-linking and stretching the polyethylene resin film according to claim 7.