KR20140083910A - Polyolefin non-stretched multilayered film - Google Patents

Abstract

The present invention relates to a polyolefin-based non-stretched multilayered film comprising: a laminate layer containing polypropylene-based resin containing polypropylene-based resin with Mw/Mn of 4 or greater and MFR of 1 to 30 g/10min, and propylene-ethylene copolymers with Mw/Mn of 1.5 to 3.5 and MFR of 1 to 30g/10min; a middle layer containing polyethylene-based resin containing ethylene-α-olefin copolymers with density of 0.90 to 0.94 g/cm^3 and MFR of 0.5 to 20 g/10min; and a heat-sealing layer containing polypropylene-based resin containing propylene-ethylene copolymers with Mw/Mn of 1.5 to 3.5, MFR of 1 to 30g/10min and a melting point of 125 to 140°C.

Description

[0001] POLYOLEFIN NON-STRETCHED MULTILAYERED FILM [0002]

The present invention relates to a polyolefin-based non-drawn multilayer film. In particular, optical properties such as high transparency, high gloss and high image clarity; Blocking property; Low-temperature heat sealing property and the like, and at the same time,

A heat sealing strength in the case of joining with a base film to form a composite film; Tear openness of packaging; And a polyolefin-based non-oriented multilayered film excellent in the pin-hole property of the heat-sealed portion.

BACKGROUND ART Polyolefin-based resin films are widely used as materials for packaging various products. For food packaging applications; Packaging of daily necessities such as textiles and medical supplies; And packaging of industrial parts. Particularly, since the polypropylene resin film is excellent in rigidity and heat resistance and also has a high elastic feeling (waist feeling) of the film, it has been widely used because of its high suitability for the atmosphere. However, the polypropylene-based resin film does not have sufficient heat-sealability (particularly low-temperature heat-sealability), impact resistance and pinch-resistance of the heat-sealed portion. Therefore, attempts have been made to improve the heat sealability and the impact resistance by copolymerizing the polypropylene of the film material. However, the effect on impact resistance particularly at low temperature has not been obtained so much. In addition, when attempting to improve heat sealability, a problem of blocking occurs. Therefore, attempts to convert the copolymer into a copolymer have not been successful.

In this regard, in Japanese Patent Application Laid-Open (kokai) No. 5-147179, by laminating the intermediate layer and the polypropylene type resin layer as the both outer layers using a linear ethylene -? - olefin copolymer (LLDPE) A polyolefin-based multilayer film having improved impact resistance has been proposed. According to this method, improvement of the impact resistance is certainly confirmed, but optical properties (transparency, gloss, mattness, etc.) of the laminated film are impaired. Further, when the laminated film is bonded to a base film to form a composite film, the tear strength becomes extremely high, so that the tearing and sealing performance when the laminated film is used as a packaging material is remarkably impaired.

Japanese Patent Application Laid-Open No. 2004-276373 proposes a polyolefin-based multilayer film improved in low-temperature heat-sealability and anti-blocking property by laminating a specific polypropylene-based polymer as an outer layer and an LLDPE layer as an intermediate layer. Even with this technique, the obtained composite film has a very high tear strength, and the tearing and releasing property when it is used as a packaging material is not satisfactory.

The pinhole resistance of the above-mentioned heat-sealed portion is an index indicating that there is no fine conduction path in the heat-sealed region and the sealing property is complete. The presence of a fine conduction path in the heat-sealing portion deteriorates the sealability of the package, and is therefore not preferable from the viewpoints of maintaining the contents of the food, preserving the contents for a long period of time, and the like. The pinhole resistance of the heat-sealed portion is a concept that is completely different from the heat-sealing strength. In the prior art, there has been almost no attempt to improve the pinhole resistance of the heat-sealed portion with respect to the polypropylene-based resin film.

Therefore, optical properties such as high transparency, high gloss, and high image quality; Blocking property; Low-temperature heat sealing property and the like, and at the same time,

A heat sealing strength in the case of joining with a base film to form a composite film; Tear openness of packaging; A polyolefin-based non-smelting multilayer film which is excellent in the pin-hole property of the heat sealing portion and the like is not heretofore known.

The present invention has been made in view of the above circumstances.

Accordingly, an object of the present invention is to provide an optical film, which has optical properties such as high transparency, high gloss, and high image quality; Blocking property; Low-temperature heat-sealability, and the like, and at the same time, the heat-sealing strength when a composite film is formed by bonding to a base film; Tear openness of packaging; And to provide a polyolefin-based non-smelting multilayer film excellent in the pinhole resistance of the heat sealing portion.

According to the present invention, the above objects and advantages of the present invention

A non-oriented polyolefin multilayer film having a laminate layer as an outermost layer, an intermediate layer of at least one layer, and a heat-sealing layer as another outermost layer,

The laminate layer

A melt flow rate (MFR) measured at 230 占 폚 under a load of 2.16 kg in accordance with JIS K 7210 of not less than 4 and a molecular weight distribution Mw / Mn expressed by a ratio of a weight average molecular weight Mw and a number average molecular weight Mn, 10 to 50 parts by weight of a polypropylene resin (A1) having a melt flow rate of 30 g / 10 min, and

A melt flow rate MFR of 1 to 30 g / 10 min as measured at 230 占 폚 under a load of 2.16 kg in accordance with JIS K 7210 according to a molecular weight distribution Mw / Mn of 1.5 to 3.5, 50 to 90 parts by weight of the copolymer (A2)

(Provided that the total of the polypropylene resin (A1) and the propylene-ethylene copolymer (A2) is 100 parts by weight)

And a polypropylene resin,

The intermediate layer

? -Olefin copolymer (B) having a density of 0.90 to 0.94 g / cm ³ and a melt flow rate MFR of 0.5 to 20 g / 10 min as measured at 190 占 폚 under a load of 2.16 kg in accordance with JIS K 7210, % Or more of a polyethylene-based resin,

The heat-

A molecular weight distribution Mw / Mn of 1.5 to 3.5, a melt flow rate MFR of 1 to 30 g / 10 min measured at 230 캜 under a load of 2.16 kg in accordance with JIS K 7210, a melting point of 125 to 140 캜, Containing polypropylene resin containing 70% by weight or more of a propylene-ethylene copolymer (C)

≪ / RTI >

The polyolefin-based non-smelting multilayer film of the present invention has a laminate layer as an outermost layer, an intermediate layer of at least one layer, and a heat-sealing layer as another outermost layer.

≪ Laminate layer >

The laminate layer in the polyolefin non-oriented multilayered film of the present invention contains a polypropylene resin containing 10 to 50 parts by weight of a polypropylene resin (A1) and 50 to 90 parts by weight of a propylene-ethylene copolymer (A2) . However, the total amount of the polypropylene resin (A1) and the propylene-ethylene copolymer (A2) is 100 parts by weight.

[Polypropylene resin (A1)]

The polypropylene resin (A1) has a molecular weight distribution Mw / Mn expressed by the ratio of the weight average molecular weight Mw to the number average molecular weight Mn of 4 or more. The value of Mw / Mn is preferably 4.5 to 10, more preferably 5 to 8. When the Mw / Mn of the polypropylene resin (A1) is less than 4, the obtained multilayered film and the composite film produced using the multilayered film become excessively high in tear strength, so that the effect of improving the tearing-opening property of the packaging material is not exhibited do. This is considered to be due to the fact that when the Mw / Mn is smaller than 4, the melt orientation is hardly generated in the production of the multilayered film. On the other hand, Mw / Mn is preferably 10 or less from the viewpoint of suppressing the melt tension in an appropriate range when producing the multilayered film and ensuring the blocking resistance when the multilayered film is formed. The polypropylene resin (A1) preferably has an Mw of 450,000 to 100,000, more preferably 400,000 to 200,000.

The weight-average molecular weight Mw and the number-average molecular weight Mn are values in terms of polystyrene measured by gel permeation chromatography (GPC) (the same is applied hereinafter).

The polypropylene resin (A1) has a melt flow rate MFR of 1 to 30 g / 10 min as measured at 230 占 폚 under a load of 2.16 kg in accordance with JIS K 7210. This value is preferably 5 to 15 g / 10 min. When the MFR is less than 1 g / 10 min, the melt viscosity is excessively low, so that the pressure in the extruder (for example, an extruder) during the production of the multilayer film becomes excessively high, and the productivity may be lowered. Further, there are cases where defective appearance such as unevenness in film thickness and melt fracture occurs. On the other hand, when the MFR exceeds 30 g / 10 min, the difference in melt viscosity with the resin of the intermediate layer becomes excessive, and the film thickness of the outer layer may become uneven. In addition, there is a case where the anti-blocking property in the case of using a multilayer film is impaired.

The polypropylene resin (A1) preferably has a melting point of 120 to 150 캜, more preferably 130 to 145 캜. The polypropylene resin (A1) showing a melting point at a temperature within this range is preferable in that the heat resistance at the time of producing the multilayered film and the transparency at the time of forming the multilayered film and the composite film are excellent. Here, the melting point of the resin refers to the peak top temperature (Tm) of the maximum endothermic peak in the differential scanning calorimetry (DSC) chart (the same is applied hereinafter).

The polypropylene resin (A1) may be a homopolymer of propylene or a copolymer of propylene and a copolymerizable component. Examples of the copolymerization component to be used here are ethylene and? -Olefin, and specific examples thereof include ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, Decene, 4-methyl-1-pentene, and the like, and at least one selected from these may be used. The proportion of the copolymer component in the polypropylene resin (A1) is preferably 10 mol% or less, more preferably 5 mol% or less, and further preferably 3 mol% or less.

The polypropylene resin (A1) in the present invention is preferably a homopolymer of propylene, a copolymer of propylene and ethylene, and a copolymer of propylene and ethylene and butene, in view of securing the optical properties of the resulting multilayered film and composite film It is preferable to use at least one selected from the group consisting of

The polypropylene resin (A1) may be produced by any method as long as it satisfies the above-mentioned conditions. For example, a known Ziegler-Natta catalyst can be prepared, preferably using a suitable donor compound. The Ziegler Natta catalyst may be supported on a suitable inorganic material.

[Propylene-Ethylene Copolymer (A2)]

The propylene-ethylene copolymer (A2) has a molecular weight distribution Mw / Mn expressed as a ratio of a weight average molecular weight Mw to a number average molecular weight Mn of 1.5 to 3.5. The value of Mw / Mn is preferably 1.8 to 3.2, more preferably 2.0 to 3.0. When the Mw / Mn of the propylene-ethylene copolymer (A2) is less than 1.5, the melt tension is insufficient and the film-forming property is deteriorated. On the other hand, Mw / Mn is preferably 3.5 or less from the viewpoint of ensuring the blocking resistance in the case of a multilayered film and securing the optical characteristics in the multilayered film and the composite film. The propylene-ethylene copolymer (A2) preferably has an Mw of 450,000 to 100,000, more preferably 400,000 to 200,000.

The propylene-ethylene copolymer (A2) has a melt flow rate MFR of 1 to 30 g / 10 min as measured at 230 占 폚 under a load of 2.16 kg in accordance with JIS K 7210. This value is preferably 5 to 15 g / 10 min. When the MFR is less than 1 g / 10 min, the melt viscosity is excessively low, so that the pressure in the extruding stage (for example, an extruder) during the production of the multilayer film becomes excessively high and the productivity may be lowered. Further, there are cases where defective appearance such as unevenness in film thickness and melt breakage may occur. On the other hand, if the MFR exceeds 30 g / 10 min, the difference in melt viscosity with the resin of the intermediate layer becomes excessive, and the film thickness of the outer layer may become uneven. In addition, there is a case where the anti-blocking property in the case of using a multilayer film is impaired.

The propylene-ethylene copolymer (A2) preferably has a melting point of 120 to 145 占 폚, more preferably 120 to 140 占 폚, still more preferably 120 to 135 占 폚. The propylene-ethylene copolymer (A2) having a melting point in the range of the above range is preferable in that the heat resistance at the time of producing the multilayered film and the transparency at the time of forming the multilayered film or the composite film are excellent.

The content of the ethylene unit in the propylene-ethylene copolymer (A2) is preferably 1 to 10 mol%, and more preferably 2 to 5 mol%. By setting the content of the ethylene unit in this range, it is possible to exhibit excellent blocking resistance without impairing transparency in the resulting multilayer film, which is preferable.

The propylene-ethylene copolymer (A2) is obtained by polymerization using a metallocene catalyst. The propylene-ethylene copolymer (A2) polymerized by using the metallocene catalyst is preferable because the resulting multilayered film exhibits high blocking resistance and exhibits excellent optical properties when used as a multilayered film and a composite film.

The metallocene catalyst is a catalyst comprising a metallocene-type transition metal compound having at least one, preferably two, substituted or unsubstituted cyclopentadienyl ligands and a cocatalyst. As the co-catalyst, for example, an organoaluminum compound; A complex of an organic boron compound and a cation; Ion-exchangeable silicates, and the like, and at least one selected from these can be used. The metallocene catalyst may be carried on a suitable inorganic material. Metallocene catalysts are well known in the art, and a suitable metallocene catalyst can be appropriately selected and used according to the purpose of those skilled in the art.

[Optional ingredients]

The polypropylene resin in the laminate layer of the polyolefin-based non-smelting multilayer film of the present invention contains the above-mentioned polypropylene resin (A1) and propylene-ethylene copolymer (A2) as essential components, But may contain other polymers in addition to these insofar as the effect is not impaired. The other polymer used herein is a polymer other than the above-mentioned polypropylene resin (A1) and propylene-ethylene copolymer (A2). The content of other polymer is preferably 10% by weight or less, more preferably 5% by weight or less based on the total amount of the polypropylene resin (A1), the propylene-ethylene copolymer (A2) Most preferably it does not contain it.

The laminate layer of the polyolefin-based non-smelting multilayer film of the present invention may contain, in addition to the polypropylene-based resin as described above, optional additives such as heat stabilizers, processing stabilizers, lubricants, nucleating agents, antistatic agents, antifogging agents, Antioxidants, ultraviolet absorbers, pigments, and the like. These additives may be added directly to a polymer constituting the polypropylene resin, or may be added by a method of blending them into a master batch containing these additives at a high concentration. As the base resin of the master batch, one or more of the above-mentioned polypropylene resin (A1) and propylene-ethylene copolymer (A2) and, if used, other polymer may be used.

[Modes of Laminate Layer]

The polypropylene resin in the laminate layer of the polyolefin-based non-smelting multilayer film of the invention contains 10 to 50 parts by weight of the polypropylene resin (A1) and 50 to 90 parts by weight of the propylene-ethylene copolymer (A2). Preferably 20 to 40 parts by weight of the polypropylene resin (A1) and 60 to 80 parts by weight of the propylene-ethylene copolymer (A2). However, the total of the polypropylene resin (A1) and the propylene-ethylene copolymer (A2) is 100 parts by weight.

By blending the polypropylene resin (A1) with the polypropylene resin of the laminate layer, the tear strength of the obtained multilayered film and the composite film is set to an appropriate range, and the tearing and opening performance of the packaging material is improved. This is presumably because the molecular weight distribution of the polypropylene resin constituting the laminate layer (outer layer) is broadened by the blending of the polypropylene resin (A1), and thus the melt orientation tends to occur at the time of producing the multilayer film. For this reason, the laminate layer in the present invention needs to contain at least 10 parts by weight of the polypropylene resin (A1), and it is preferable that the laminate layer contains at least 20 parts by weight of the polypropylene resin (A1).

On the other hand, when the propylene-ethylene copolymer (A2) is blended with the polypropylene resin of the laminate layer, optical properties such as transparency, gloss and mattness are improved in the resulting multilayered film and composite film, and the anti- . Therefore, the laminate layer in the present invention needs to contain 50 parts by weight or more of the propylene-ethylene copolymer (A2), and it is preferable that the laminate layer contains 60 parts by weight or more of the propylene-ethylene copolymer (A2).

As the polymer to be blended with the polypropylene resin of the laminate layer, it is preferable that the polymer is composed solely of the polypropylene resin (A1) and the propylene-ethylene copolymer (A2).

The thickness of the laminate layer in the polyolefin-based non-oriented multilayered film of the present invention is preferably 1.0 to 30 탆, more preferably 2.5 to 25 탆. Setting the laminate layer to a thickness within this range is preferable in that a high impact resistance can be obtained without impairing heat resistance and tearing and sealing properties in the obtained multilayered film and composite film.

<Middle layer>

The intermediate layer in the polyolefin-based non-smelting multilayer film of the present invention contains a polyethylene-based resin containing 70% by weight or more of the ethylene -? - olefin copolymer (B). The polymer in the polyethylene-based resin in the intermediate layer may be composed only of the ethylene -? - olefin copolymer (B) or may contain other polymers together with the ethylene -? - olefin copolymer (B).

[Ethylene -? - olefin copolymer (B)]

The ethylene /? - olefin copolymer (B) has a density of 0.90 to 0.94 g / cm ³ . The density of the ethylene -? - olefin copolymer (B) is preferably 0.91 to 0.93 g / cm ³ . When the density is less than 0.90 g / cm ³ , the resulting multilayered film has insufficient rigidity, and handling properties for the atmosphere deteriorate when the multilayered film or the composite film is used as a packaging material. On the other hand, the density of the ethylene -? - olefin copolymer (B) is preferably 0.94 g / cm ³ or less in order to sufficiently exhibit the effect of improving the impact resistance of the resulting multilayered film and composite film.

The ethylene /? - olefin copolymer (B) has a melt flow rate MFR of 0.5 to 20 g / 10 min as measured at 190 占 폚 under a load of 2.16 kg in accordance with JIS K 7210. The MFR is preferably 1 to 10 g / 10 min. When the MFR is less than 0.5 g / 10 min, the melt viscosity is excessively high, so that the pressure in the extruder (for example, an extruder) during the production of the multilayer film becomes excessively high and the productivity may be lowered. In addition, there are cases where the film thickness is uneven. On the other hand, if the MFR exceeds 20 g / 10 min, the difference in melt viscosity with the resin of the outer layer becomes excessive, and the film thickness of the outer layer may become uneven. In addition, the thickness of the multilayer film may be uneven.

The ethylene /? - olefin copolymer (B) preferably has an Mw of 250,000 to 30,000, and more preferably 200,000 to 50,000.

The ethylene /? - olefin copolymer (B) preferably has a melting point of 90 to 135 占 폚, more preferably 100 to 125 占 폚. The ethylene /? - olefin copolymer (B) exhibiting a melting point at a temperature within this range is preferable in that the obtained multilayer film and composite film have excellent balance between impact resistance and rigidity.

The ethylene -? - olefin copolymer (B) is a copolymer of ethylene and an? -Olefin. Examples of the? -Olefin to be used herein include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, And at least one selected from these can be used. The proportion of the? -Olefin component in the ethylene -? - olefin copolymer (B) is preferably 1 to 25 mol%, more preferably 5 to 20 mol%.

The ethylene -? - olefin copolymer (B) may be produced by any method as long as it satisfies the above conditions. For example, by using a known Ziegler Natta catalyst, preferably with a suitable donor compound; A method using a Phillips catalyst, or the like. These catalysts may be supported on suitable inorganic materials.

[Other Polymers]

The polyethylene resin of the intermediate layer in the polyolefin-based non-oriented multilayered film of the present invention contains the above-mentioned ethylene -? - olefin copolymer (B), but the ethylene -? - olefin copolymer (B) . &Lt; / RTI &gt; Examples of other polymers usable herein include a polypropylene resin, a homopolymer of ethylene, and a thermoplastic elastomer. As the other polymer, it is preferable to use a homopolymer of ethylene which exhibits a lower MFR than that of the ethylene -? - olefin copolymer (B) among the above, so that the obtained tear strength of the multilayered film and the composite film is in a suitable range, It is preferable from the viewpoint that the balance of the tear openability is excellent. This phenomenon is considered to be due to the fact that the melt orientation becomes stronger when the multilayer film is produced by using the ethylene-a-olefin copolymer (B) and a homopolymer of ethylene as described above in combination. The melt flow rate MFR of the homopolymer of ethylene measured according to JIS K 7210 at 190 占 폚 under a load of 2.16 kg is preferably 0.1 to 5 g / 10 min, more preferably 0.5 to 2.5 g / 10 min . The MFR is preferably 50% or less of the MFR value of the ethylene -? - olefin copolymer (B).

[additive]

The intermediate layer in the polyolefin-based non-smelting multilayer film of the present invention may further contain an additive in addition to the polyethylene-based resin as described above.

Examples of additives usable herein include heat stabilizers, processing stabilizers, lubricants, nucleating agents, antistatic agents, anti-fogging agents, anti-blocking agents, antioxidants, ultraviolet absorbers and pigments. These additives may be added directly to each resin or may be added in a master batch containing these additives at a high concentration. As the base resin of the master batch, one or more of the above-mentioned ethylene -? - olefin copolymer (B) and, if used, other polymers may be used.

[Modes of intermediate layer]

The blending of the ethylene-α-olefin copolymer (B) in the polyethylene resin of the intermediate layer contributes to the improvement of the impact resistance and the mattness in the resulting multilayered film and composite film. If the ratio of the ethylene-? -Olefin copolymer (B) in the polyethylene-based resin in the intermediate layer is less than 70% by weight, the degree of the above-described effect may be insufficient. The proportion of the ethylene /? - olefin copolymer (B) in the polyethylene-based resin in the intermediate layer is preferably 75% by weight or more, and more preferably 85% by weight or more.

In addition, in the polyolefin-based non-oriented multilayered film of the present invention, the polyethylene-based resin in the intermediate layer is composed of at least 70% by weight of the majority of the ethylene -? - olefin copolymer (B) as described above. Therefore, even if a resin other than a polyethylene-based resin (for example, a polypropylene-based resin) is blended in addition to the ethylene-? -Olefin copolymer (B), those skilled in the art can call the entirety thereof as polyethylene-based resin.

The polymer to be blended with the polyethylene-based resin in the intermediate layer is preferably a polymer composed only of the ethylene-? -Olefin copolymer (B) or the ethylene? -Olefin copolymer (B) and the other polymer And a homopolymer of ethylene exhibiting a lower MFR than that of the copolymer (B)).

The thickness of the intermediate layer in the polyolefin-based non-oriented multilayer film of the present invention is preferably 5 to 80 탆, more preferably 10 to 50 탆. By setting the thickness of the intermediate layer within this range, it is preferable that the multilayered film and the composite film to be obtained have high impact resistance and excellent mismatch without compromising the rigidity of the multilayered film.

The intermediate layer may be composed of only one layer, or may be a laminate of two or more layers. In the latter case, each layer constituting the intermediate layer is selected from the above-mentioned polyethylene resin. The polyethylene-based resin constituting each layer may be the same as or different from the polyethylene-based resin, and may or may not have all of the type and the optional proportion (other polymer and additive) of the polyethylene-based resin, It is possible.

When the intermediate layer contains a laminate of a polyethylene-based resin, the number of laminated layers is preferably 2 to 4, more preferably 2 to 3. It is preferable that the thickness of the laminate is within the above-mentioned range as the thickness of the intermediate layer. The thickness of each layer constituting the laminate is preferably 2 to 40 탆, more preferably 5 to 25 탆.

<Heat Sealing Layer>

The heat-sealing layer in the polyolefin-based non-smelting multilayer film of the present invention contains a polypropylene-based resin containing 70% by weight or more of the propylene-ethylene copolymer (C). The polymer in the polypropylene resin of the heat-sealing layer may be composed only of propylene-ethylene copolymer (C) or may contain other polymer together with propylene-ethylene copolymer (C).

[Propylene-Ethylene Copolymer (C)]

The propylene-ethylene copolymer (C) is obtained by polymerization using a metallocene catalyst. The propylene-ethylene copolymer (C) has the same properties as those described for the propylene-ethylene copolymer (A2) except that the propylene-ethylene copolymer (C) has a melting point of 125 to 140 ° C as an essential requirement. A detailed description of the metallocene catalyst is also the same as that described in the production process of the propylene-ethylene copolymer (A2).

The melting point of the propylene-ethylene copolymer (C) is preferably 120 to 140 占 폚, more preferably 120 to 135 占 폚.

The propylene-ethylene copolymer (C) in the heat-sealing layer may be the same as the propylene-ethylene copolymer (A2) compounded in the laminate layer, or may be of a different kind with different parameters.

[Other Polymers]

The other polymer can be selected and used without particular limitation as long as the effect of the present invention is not impaired. However, when considering improvement of the tear openability of the packaging material, which is one of the main features of the present invention, it is preferable to use a polypropylene resin other than the propylene-ethylene copolymer (C) as the other polymer, It is preferable to use the same one as the polypropylene resin (A1) blended in the layer. That is, it is a polypropylene type resin having a molecular weight distribution Mw / Mn of 4 or more and a melt flow rate MFR of 1 to 30 g / 10 min as measured according to JIS K 7210 at 230 占 폚 under a load of 2.16 kg. The melting point of the polypropylene resin is preferably 120 to 150 ° C, more preferably 130 to 145 ° C.

[additive]

The polypropylene resin of the heat-sealing layer in the polyolefin-based non-smelting multilayer film of the present invention may further contain an additive in addition to the above-mentioned propylene-ethylene copolymer (C) and optionally other polypropylene- It is possible.

Examples of additives usable herein include heat stabilizers, processing stabilizers, lubricants, nucleating agents, antistatic agents, anti-fogging agents, anti-blocking agents, antioxidants, ultraviolet absorbers and pigments. These additives may be added by a method directly blended to each resin, or may be added by a method of blending them as a master batch containing these additives at a high concentration. As the base resin for the master batch, one or more of the above-mentioned propylene-ethylene copolymer (C) and, if used, other polymers may be used.

[Modes of heat-sealing layer]

The blending of the propylene-ethylene copolymer (C) with the polypropylene resin of the heat-sealing layer is effective in improving the blocking resistance, the low-temperature heat-sealing property, the strength of the heat-sealed portion, and the pinhole resistance of the heat- . When the proportion of the propylene-ethylene copolymer (C) in the polypropylene resin of the heat-sealing layer is less than 70% by weight, the degree of the above-described effect is not sufficient. The proportion of the propylene-ethylene copolymer (C) in the polypropylene resin of the heat-sealing layer is preferably 80% by weight or more, and more preferably 90% by weight or more.

It is preferable that the polymer to be blended with the polypropylene resin of the heat-sealing layer is made of only the propylene-ethylene copolymer (C) or only the propylene-ethylene copolymer (C) and the polypropylene resin.

The thickness of the heat-sealing layer in the polyolefin-based non-smelting multilayer film of the present invention is preferably 2 to 30 μm, more preferably 2.5 to 25 μm. By setting the thickness of the heat-sealing layer to this range, it is preferable that the resulting multilayered film and composite film have high impact resistance without deteriorating the low-temperature heat-sealability and pinhole resistance.

&Lt; Thickness of Polyolefin-Based Smooth Multilayer Film >

The thickness of the polyolefin-based non-smelting multilayer film of the present invention can be suitably set in accordance with its use and its use. Here, the use mode is a choice of using the multilayer film of the present invention as a packaging material or bonding to a film substrate to use as a composite film;

Usage refers to the type, weight, etc. of the contents of the packaging material.

The thickness of the polyolefin non-oriented multilayered film of the present invention may be, for example, 10 to 100 탆, preferably 15 to 80 탆, further preferably 20 to 75 탆.

&Lt; Process for producing a polyolefin-based non-smelting multilayer film >

The polyolefin-based non-smelting multilayer film of the present invention can be produced by any method as long as it is a method substantially not involving stretching. Here, &quot; substantially not accompanied by stretching &quot; means that even a slight degree of orientation is not prohibited in the course of production of the film, which means that the film does not pass through an explicit stretching process. Therefore, for example, when an extrusion process under the generally adopted conditions is employed, it is permitted that slight orientation occurs in the extrusion direction.

As a method of producing the polyolefin-based non-oriented multilayered film of the present invention, an appropriate method such as extrusion or casting can be employed. Since resins constituting each layer of the multilayered film of the present invention all have appropriate MFRs and are highly compatible with the molten mold stopper, the use of the extrusion method described above maximizes the effects of the present invention It is preferable. As the die of the extrusion method, a T-die, a ring-shaped die, or the like can be used. However, from the viewpoint of precisely controlling the thickness of the layer and obtaining excellent optical characteristics, it is not preferable to use a ring-shaped die, and it is preferable to use a T-die or the like.

Since the polyolefin-based non-smelting multilayer film of the present invention has a laminate layer, at least one intermediate layer and a heat-sealing layer, it has a multilayer structure including at least three layers. As a method of multilayering the film, known methods such as a coextrusion method and an in-line lamination method can be employed. Examples of the co-extrusion method include a multi-manifold method and a feed block method. Among them, the co-extrusion method is preferably used because it is possible to uniformly control the thickness of each layer in the width direction.

The polyolefin-based non-smelting multilayer film of the present invention is intended to be applied as a packaging material in the form of a composite film obtained by directly laminating it or a film substrate. Therefore, in the case of the former, printing may be carried out for expressing the origin of the product or manifesting the design effect on the outermost layer surface; In the latter case, the film base is pasted on the outermost layer surface (usually the surface of the laminate layer). In this case, for the purpose of improving the affinity or adhesiveness with the ink or the adhesive, the surface treatment may be carried out in-line or off-line on the outermost layer surface (usually the surface of the laminate layer). Examples of the surface treatment include corona discharge treatment, frame (flame) treatment, and the like.

<Composite film>

The composite film of the present invention is obtained by pasting a multilayer film as described above on a film substrate with the laminate layer side of the multilayer film as a patch face. INDUSTRIAL APPLICABILITY The composite film of the present invention is excellent in low-temperature heat-sealing ability, heat-sealing strength, and pinhole resistance of a heat-sealed portion, and is also excellent in tearing and opening performance when used as a packaging material.

[Film substrate]

The material constituting the film base in the composite film of the present invention can be appropriately determined depending on the use of the packaging material. For example, a resin selected from the group consisting of a polypropylene resin, a polyethylene resin, a polyethylene terephthalate resin and a polyamide resin, or a metal. The film substrate may be a layer containing at least one material selected from the above, or may be a laminate including a plurality of such layers.

The thickness of the film base material is arbitrary depending on the use of the packaging material, but may be, for example, 5 to 75 mu m, preferably 10 to 50 mu m.

[Thickness of Composite Film]

The total thickness of the composite film of the present invention can be set arbitrarily according to the use of the packaging material, but can be, for example, 15 to 180 탆, preferably 20 to 130 탆, more preferably 30 to 120 탆 .

&Lt; Method for producing composite film &

The method for producing a composite film is not particularly limited as long as it is a method capable of attaching the multilayer film of the present invention on the film substrate with the laminate layer side thereof as a patch.

Adhesion between the film base material and the laminate layer of the multi-layer film can be performed by a suitable adhesive or by thermocompression bonding. As the adhesive used herein, a commercially available adhesive may be used, or a molten resin (for example, a molten polyethylene resin) may be used. Examples of the application method of the adhesive include transfer means such as gravure, gravure reverse, and offset; A scraping means such as a bar and a comma bar, and the like.

Examples of the method for laminating the film base material and the multilayer film (through the adhesive layer as necessary) include a dry lamination method and a thermal lamination method.

Example

Hereinafter, the present invention will be described by way of examples and comparative examples, but the present invention is not limited to these examples.

Each evaluation in the following Examples and Comparative Examples was carried out by the following procedures.

&Lt; Evaluation of multi-layer film &

(1) Hayes

As an index of transparency, the haze was measured in accordance with JIS K 7136 using a haze meter (model number: NDH5000) manufactured by Nippon Denshoku Kogyo Co., Ltd.

(2) Gloss

Gloss was measured according to JIS K 7105 using a gloss meter (model number: UGV-5D) manufactured by Suga Shikoku Co., Ltd. as an index of glossiness.

(3) Phase definition

The slit width of the optical comb was set to 0.125 mm in accordance with JIS K 7105 using an image quality measuring instrument (model number: ICM-IDP) manufactured by Suga Shikki K.K. to measure the image clarity .

(4) Blocking strength

The blocking strength as an index of the blocking resistance was examined by the following tensile test.

A multilayer film cut into a square of 120 mm x 120 mm was laminated in such a manner that the laminate layer and the heat sealing layer were in contact with each other so that the laminate layer and the heat sealing layer were in contact with each other and a load of 10 kg was applied to the entire upper surface thereof. (72 hours) for 3 days. Of the multilayered films after storage, two sheets of the upper layer and two sheets of the lower layer were removed to take six sheets in the middle, and two sheets of the adjacent sheets were peeled off to obtain three pairs of sheets. In each pair, two multilayered films are contacted with the laminate layer and the heat-sealing layer and pressed under the above-described conditions. Each pair was cut into a 30 mm x 120 mm rectangle to obtain three test pieces. The test piece was peeled off from one end of the short side so that the pressed portion was left to have a length of 40 mm. The pressed portion 30 mm x 40 mm remaining on each test piece is the measurement area for blocking resistance.

The layer of the part where the test piece was peeled off was sandwiched between two chucks using an Autograph (model number: AG-500D) manufactured by Shimadzu Seisakusho Co., Tensile test was carried out under the condition of 50 mm / min to examine the maximum value of the stress until the test piece was completely peeled off. The average value (kPa) of the maximum value was taken as the number of n, and this was regarded as the blocking strength.

(5) Impact strength

As an index of impact resistance, the impact strength was measured under the following conditions using a Film Impact Tester manufactured by Toyo Seiki Co., Ltd.

Specimen dimensions: 120mm × 120mm

Measuring temperature: 23 占 폚 atmosphere and 0 占 폚 atmosphere

(6) Tear strength (tracer heat method)

The tear strength was measured under the following conditions using an Autograph (model number: AG-500D), manufactured by Shimadzu Corporation, in accordance with JIS K 7128-1 as an index of the thermostability.

Specimen dimensions: 150 mm long, 50 mm wide

Slit: Cutting depth of 75 mm in length at the center of the short side of the test piece (transverse direction)

Tensile speed: 200 mm / min

Measuring temperature: 23 ° C Atmosphere

&Lt; Evaluation of composite film &

(7) Heat sealing strength

As the index of the heat sealability, the heat sealing layers of the two composite films were brought into contact with each other, and the strength at the time of heat sealing at each temperature was examined by the following tensile test.

The composite film was cut into a rectangle having a size of 15 mm x 200 mm and the two sheets were stacked one over the other so that the heat sealing layers were brought into contact with each other. Using a YSS heat sealer manufactured by Yasuda Seiki Seisakusho Co., Ltd., And a test piece was obtained by sealing.

Sealing bar width: 5mm

Sealing pressure: 0.1 MPa

Sealing time: 1.0 second

Sealing temperature: Variation to 150 ℃, 160 ℃ and 170 ℃

A region of 5 mm x 15 mm, which is the sheet-sealed portion of the test piece obtained above, is a measurement region of the respective heat-sealing strengths. Here, the case where the longer side of the rectangle corresponds to the extrusion direction of the film is referred to as a test piece in the &quot; longitudinal &quot; direction, and the case where the longer side of the rectangle is orthogonal to the extrusion direction of the film is referred to as &quot; Test pieces were prepared for each film in two directions x 3 temperature = 6 kinds.

The non-heat sealed portion of the test piece after heat sealing at each temperature was opened using an autograph (model number: AG-500D) manufactured by Shimadzu Corporation, and was put on each of two chucks, The tensile test was carried out under the condition of 300 mm / min to investigate the maximum value of the stress.

If the maximum value of the above stress is 3N / 15 mm or more, it can be estimated that sufficient heat sealing strength is obtained at the temperature.

(8) Immunity

A flaw detection test of the heat sealing portion was performed as an index of the pinhole resistance of the heat sealing portion.

The composite film was cut into a rectangle of 150 mm x 100 mm and folded in two at the center of the short side so that the heat sealing layer was inward. And one side of the short side portion was left as an opening, and heat sealing was performed using the YSS heat sealer manufactured by Yasuda Seiki Seisakusho Co., Ltd. for the remaining two sides (one side portion and the long side in the short side) under the following conditions Similar substitution of the envelope shape was obtained.

Heat sealing temperature: 160 ℃

Sealing pressure: 0.1 MPa

Heat sealing time: 1.0 sec

Sealing Width: 5mm

The penetration liquid FP-S standard type, manufactured by TASETO Co., Ltd., dye penetrant tester, "Penetration liquid FP-S standard type" was sprayed from the opening of the similar substitute, and the state of liquid leakage from the sealed part was visually observed and evaluated according to the following criteria.

No liquid leakage from the heat sealing part: Good (Good pinhole resistance)

With liquid leakage from the heat sealing portion: x (poor pinhole resistance)

(9) Openness

As an index of the openability of the packaging material, the heat sealing properties of the two heat sealing layers of the two composite films were examined after heat sealing.

The composite film was cut into a rectangle of 150 mm x 100 mm, and two sheets were cut into a set, and the heat sealing layers were overlapped to be in contact with each other. Using a YSS heat sealer manufactured by Yasuda Seiki Seisakusho Co., The sides were heat sealed to obtain similar substitution. The four sides of this substitute are heat sealed to the end.

Heat sealing temperature: 160 ℃

Sealing pressure: 0.1 MPa

Heat sealing time: 1.0 sec

Sealing Width: 5mm

A nick of 10 mm in the vertical direction was inserted from one end of the obtained heat seal part in place of the similar heat seal part using a cutter, and the above-mentioned notched part was cut in the transverse direction (parallel to the surface of the similar material, ), And the force required for the above-mentioned phosphorus and the state of the phosphorus portion were examined, and evaluated according to the following criteria.

It is cut linearly from the cuts with light force, and there is no film elongation or fluffing: A (very good)

It feels a bit heavier when tearing up, but it ends up straight: B (good)

When tearing up, it feels very heavy, the broken film stretches and the fluff is rising: C (bad)

The film stretches from the nick and does not break: D (very bad)

Example 1

(Production of polyolefin-based non-oriented multilayered film)

(Manufactured by NIPPON POLYPROPYLENE CO., LTD., Model number: FW3GT, melting point = 148 占 폚, MFR = 7.0 g / 10 minutes at 230 占 폚, Mw / Mn = ) And PE-1 (manufactured by Ube Maruzen Polyethylene Co., Ltd., model number: 2040FC, manufactured by Ube Maruzen Polyethylene Co., Ltd., melting point: 126 캜, MFR = 7.0 g / 10 min melting point = 118 ℃, using a MFR = 4.6g / 10 bun (190 ℃), density = 0.919g / cm ^3), a multi-layer film was prepared by the following method.

A three-layer three-layered T-die system comprising three single-screw extruders having a screw diameter of 75 mm for the intermediate layer and two single-screw extruders having a screw diameter of 50 mm for both outer layers (laminate layer and heat- Using a film-forming apparatus, 100 parts by weight of PE-1 as an intermediate layer extruder,

30 parts by weight of PP-1 and 70 parts by weight of PP-2 were mixed in an extruder for a laminate layer,

To the extruder for the heat sealing layer, 100 parts by weight of PP-2

Respectively. Further, all three extruders were extruded from respective T-dies under the conditions of a resin temperature of 250 占 폚, a residence time of 1 minute and a T-die temperature of 240 占 폚, and the three layers were combined to obtain a multilayer film through a cooling roll at 25 占 폚. This multi-layer film had a three-layer structure with a total thickness of 50 mu m and a thickness composition of three layers of approximately 1: 2: 1.

Then, corona discharge treatment was carried out so that the surface of the multilayer film on the side of the laminate layer had a wetting index of 42 mN / m, and further aging was carried out at 40 占 폚 for 24 hours to obtain a polyolefin non-oriented multilayered film.

The evaluation of the above (1) to (6) was carried out using the polyolefin-based non-oriented multilayered film. The evaluation results are shown in Table 2.

(Preparation of composite film)

The laminate layer side of the above polyolefin-based non-smelting multilayer film was attached to a biaxially stretched polypropylene film to prepare a composite film.

(Manufactured by TOYOTO MOTON CO., LTD. (Trade name, manufactured by TOYOTO MOTOR CO., LTD.) On the corona-treated side of a biaxially stretched polypropylene film (model number: Suntox-OP PA20, thickness: 25 탆, 15 g of a main agent (model number: TM-595) for the preparation of a thermosetting resin (manufactured by Nippon Polyurethane Industry Co., Ltd.), 2.7 g of a curing agent (model number: CAT-56 manufactured by the same company) and 36.8 g of ethyl acetate were mixed by means of an applicator , And dried at 80 DEG C for 1 minute. Next, the laminate layer of the polyolefin-based non-smelting multilayer film obtained above was laminated on the adhesive layer while being pressed with a hand roller, followed by aging at 40 DEG C for 3 days to obtain a composite film. Further, the unit "mill" means 0.001 inch, and 1 mil corresponds to about 25.3995 μm.

Evaluation of the above-mentioned (7) to (9) was carried out using the composite film obtained above. The evaluation results are shown in Table 2.

Examples 2 to 10 and Comparative Examples 1 to 6

A polyolefin-based non-smelting multilayered film and a composite film were produced in the same manner as in Example 1 except that the type and amount of the resin to be fed to the extruder for each layer were changed as shown in Table 1 Respectively.

The evaluation results are shown in Table 2.

Further, in Examples 4 and 5, two kinds of resins were mixed and used as the resin for the heat-sealing layer;

In Examples 9 and 10, two kinds of resins were mixed and used as the resin for the intermediate layer;

In Comparative Example 2, the polypropylene resin (A1) was not blended with the polypropylene resin for the laminate layer;

In Comparative Example 5, the propylene-ethylene copolymer (A2) was not blended with the polypropylene resin for the laminate layer;

In Comparative Example 6, polypropylene (PP-3) was used instead of the polyethylene resin as the resin for the intermediate layer, without using the propylene-ethylene copolymer (A2) as the resin for the laminate layer.

The abbreviations of the resin materials in Table 1 are as follows.

Mw / Mn = 5.3 (melting point = 148 占 폚, MFR = 7.0 g / 10 min (230 占 폚), manufactured by Nippon Polypropylene Co.,

Mw / Mn = 3.0 (MFR = 7.0 g / 10 min (230 占 폚), melting point = 126 占 폚, PP-2: manufactured by Nippon Polypropylene Co.,

Mw / Mn = 4.5 (melting point = 139 占 폚, MFR = 7.0 g / 10 min (230 占 폚), manufactured by Nippon Polypropylene Co.,

PP-4: manufactured by Nippon Polypropylene, Model No .: WFW4, melting point = 134 占 폚, MFR = 7.5 g / 10 min (230 占 폚), Mw / Mn = 2.9

PE-1: Ube Maruzen Polyethylene Co., Ltd., model number: 2040FC, melting point = 118 ℃, MFR = 4.6g / 10 bun (190 ℃), density = 0.919g / cm ³

PE-2: Ube Maruzen Polyethylene Co., Ltd., model number: 1540F, melting point = 113 ℃, MFR = 3.6g / 10 bun (190 ℃), density = 0.913g / cm ³

PE-3: manufactured by Ube Maruzen Polyethylene Co., model number: R500, MFR = 0.5 g / 10 min (190 캜)

PE-4: Ube Maruzen Polyethylene Co., Ltd., Model No: Z372, melting point = 119 ℃, MFR = 5.3g / 10 bun (190 ℃), density = 0.934g / cm ³

PE-5: Sumitomo Chemical Co., Ltd., model number: FV402, melting point = 109 ℃, MFR = 3.6g / 10 bun (190 ℃), density = 0.913g / cm ³

Effects of the Invention

The polyolefin-based non-smelting multilayered film of the present invention is excellent in optical properties such as high transparency, high gloss, and high image quality, and therefore has excellent visibility and designability when used as a packaging material. Since the multilayered film of the present invention is excellent in blocking resistance, it can be stored as a winding for a long period of time. The multilayered film of the present invention is excellent in low-temperature heat-sealing property, heat-sealing property and pin-hole property of the heat-sealed portion even when the film is used as a single film or when it is bonded to a film substrate to form a composite film. Can be stored. Further, since the multilayered film of the present invention has an appropriate tear strength, it is excellent in balance between durability as a packaging material and tearing and opening performance.

Therefore, the polyolefin-based non-smelting multilayer film of the present invention can be very preferably used as a sealant in packaging materials and packaging materials.

Claims (5)

A non-oriented polyolefin multilayer film having a laminate layer as an outermost layer, an intermediate layer of at least one layer, and a heat-sealing layer as another outermost layer,
The laminate layer
A melt flow rate (MFR) measured at 230 占 폚 under a load of 2.16 kg in accordance with JIS K 7210 of not less than 4 and a molecular weight distribution Mw / Mn expressed by a ratio of a weight average molecular weight Mw and a number average molecular weight Mn, 10 to 50 parts by weight of a polypropylene resin (A1) having a melt flow rate of 30 g / 10 min, and
A melt flow rate MFR of 1 to 30 g / 10 min as measured at 230 占 폚 under a load of 2.16 kg in accordance with JIS K 7210 according to a molecular weight distribution Mw / Mn of 1.5 to 3.5, 50 to 90 parts by weight of the copolymer (A2)
(Provided that the total of the polypropylene resin (A1) and the propylene-ethylene copolymer (A2) is 100 parts by weight)
And a polypropylene resin,
The intermediate layer
? -Olefin copolymer (B) having a density of 0.90 to 0.94 g / cm ³ and a melt flow rate MFR of 0.5 to 20 g / 10 min as measured at 190 占 폚 under a load of 2.16 kg in accordance with JIS K 7210, % Or more of a polyethylene-based resin,
The heat-
A molecular weight distribution Mw / Mn of 1.5 to 3.5, a melt flow rate MFR of 1 to 30 g / 10 min measured at 230 캜 under a load of 2.16 kg in accordance with JIS K 7210, a melting point of 125 to 140 캜, Containing polypropylene resin containing 70% by weight or more of a propylene-ethylene copolymer (C)
Lt; / RTI &gt; film. The multilayer film according to claim 1, wherein the polymer in the polypropylene resin of the heat-sealing layer is made of only the propylene-ethylene copolymer (C). 3. The multilayer film according to claim 1 or 2, wherein the laminate layer, the intermediate layer and the heat-sealing layer are laminated by a co-extrusion method. A composite film obtained by bonding a multilayer film according to any one of claims 1 to 3 on a film substrate with the laminate side of the multilayer film as a bonding face. The composite film according to claim 4, wherein the film base has at least a layer made of a resin or metal selected from the group consisting of a polypropylene resin, a polyethylene resin, a polyethylene terephthalate resin and a polyamide resin.