KR100189266B1 - Polypropylene mat film - Google Patents

Abstract

The present invention relates to a metalocene catalyst-based propylene copolymer resin with respect to 100 parts by weight of a resin composition composed of 40 to 80% by weight of polypropylene resin and 60 to 20% by weight of high density polyethylene resin having a density of 0.94 to 0.97 g / cm 3. The polypropylene-based matte film of the present invention is obtained by biaxially stretching a disc sheet extruded from a composition to which 20 parts by weight is added. The polypropylene-based matte film of the present invention is excellent in appearance and mechanical properties. Because of its high quality due to its matteness, it is suitable for use in adhesive tape materials, stationery covers and cases, fashion bags, and food packaging materials.

Description

Polypropylene Matte Film

The present invention relates to a polypropylene-based film having a matte effect, and more particularly, to a film such as a pressure-sensitive adhesive tape base material, a stationery cover or a case, a fashion bag, a food packaging material, etc., having excellent mechanical properties and high quality due to the mat property. It relates to a polypropylene-based matt film that can be effectively used.

As a method of manufacturing a matte film conventionally, the method of making a groove surface by grind | polishing the film surface with metal powder, the embossing method of processing a film into the uneven roll, etc. are known. However, this conventional method is difficult to produce a uniform film because of the rubbing of the surface of the film or the uneven size of the grooves because of rubbing the surface of the film already formed. Moreover, this method had the disadvantage of poor mechanical properties and easy tearing.

Another method for producing a matte film is a method of molding a composition of a thermoplastic material and a rubbery material into a sheet and then stretching the film to obtain a film. As a result, the impact strength is improved, but due to the fine holes on the surface of the film, the tensile strength is weak and easy to shrink, which is not suitable for film use. In order to improve this disadvantage, European Patent Application No. 622,186 uses a composition obtained through a kneading process by mixing a polypropylene resin with a high-density polypropylene resin that is not mutually usable, and then undergoes a translucent and To produce a matte film expressing quenching properties, Japanese Patent Publication No. 51-33150 discloses a biaxial stretching process using a resin composition in which polystyrene is added to a mixture of such a polypropylene resin and a high density polyethylene. A method of obtaining a matte film has been proposed.

However, the high density polyethylene or polystyrene added to the polypropylene resin does not have good compatibility with the polypropylene resin, so a large amount of fisheye (or polymer gel) is generated, resulting in poor film appearance, high quality matteness, and tensile strength. There is a defect such as poor mechanical properties, unstable thickness uniformity during film extrusion, and there is an urgent need for improvement.

Accordingly, the present inventors have intensively researched to improve the above problems, and as a result, by manufacturing a biaxially stretched polypropylene film using a novel polyolefin resin composition, defects in processing such as thickness unevenness during film forming are removed. In addition, the present invention was completed by developing a matte film having a good mechanical appearance such as tensile strength while having a good film appearance and excellent mat property.

An object of the present invention is to provide a novel polypropylene-based matt film having excellent appearance, matte and mechanical properties at the same time without problems in the processing process such as thickness non-uniformity.

The present invention relates to a metalocene catalyst-based propylene copolymer resin with respect to 100 parts by weight of a resin composition composed of 40 to 80% by weight of polypropylene resin and 60 to 20% by weight of high density polyethylene resin having a density of 0.94 to 0.97 g / cm 3. The present invention relates to a polypropylene mat-like film obtained by biaxially stretching a disc sheet extruded from a composition to which 20 parts by weight is added.

Hereinafter, the present invention will be described in more detail.

In the present invention, the polypropylene resin is a propylene homopolymer or propylene-α-olefin copolymer mainly composed of propylene polymerized using a conventional Ziegler-Natta catalyst, and as a copolymer, for example, a propylene-ethylene copolymer, Propylene-butene-1 copolymers, propylene-ethylene-butene-1 copolymers, and the like, or mixtures thereof. The content of α-olefin which is a comonomer is 15 mol% or less, preferably 10 mol% or less.

The melt resin of the polypropylene resin suitable for the present invention is suitably in the range of 0.1 to 20 g / 10 minutes (measured at 230 ° C and 2.16 kg by ASTM D 1238-70), preferably 0.5 to 5.0 g / 10 minutes. to be. If the melt index is less than 0.1g / 10min, there is a possibility that polymer gel is formed due to poor compatibility, and a large amount of fisheye may occur.If it exceeds 20g / 10min, the thickness uniformity becomes poor and the strength is poor. have.

In the present invention, the high density polyethylene resin is an ethylene homopolymer or ethylene-α-olefin copolymer mainly composed of ethylene having a density of 0.94-0.97 g / cm 3 polymerized using a conventional Ziegler-Natta catalyst. Examples of the copolymers include ethylene-propylene copolymers, ethylene-butene-1 copolymers, ethylene-propylene-butene-1 copolymers and the like, or mixtures thereof. The content of α-olefin which is a comonomer is usually 10 mol% or less, Preferably it is 5 mol% or less.

The melt index of the high density polyethylene resin suitable for the present invention is suitably in the range of 0.02 to 20 g / 10 minutes (measured at 190 ° C and 2.16 kg by ASTM D 1238-70), preferably 0.04 to 2.0 g / 10 minutes. to be. If the melt index is less than 0.02 g / 10 minutes, the mat properties tend to be excellent, but the compatibility is poor, polymer gels are formed, which may cause a large amount of fisheye, and if it exceeds 20 g / 10 minutes, the mat properties may be poor. There is a disadvantage of falling out and poor strength.

In the present invention, in the mixture of the polypropylene resin and the high density polyethylene resin, the high density polyethylene resin is preferably added at 20 to 60% by weight, preferably in the range of 30 to 50% by weight. If the high-density polyethylene resin is less than 20% by weight, the mat property is poor, and if it exceeds 60% by weight, the tensile strength is poor, there is a fear that the thickness irregularity occurs or the drawability is poor.

In the present invention, the metalocene catalyst-based propylene copolymer resin is a propylene-α-olefin copolymer mainly composed of propylene polymerized using a metalocene-based catalyst as the isotactic propylene copolymer resin, and as a copolymer, for example, propylene- Ethylene copolymers, propylene-butene-1 copolymers, propylene-ethylene-butene-1 copolymers, and the like, or mixtures thereof. The content of α-olefin which is a comonomer is 15 mol% or less, preferably 10 mol%. It is as follows.

The propylene copolymer prepared using the metalocene catalyst has a stereoregular relationship in that the propylene copolymer resin prepared using a conventional Ziegler-Natta catalyst is polymerized at a single active point as compared to polymerized at a multiactive point. It has excellent properties and has a narrow molecular weight distribution, and its manufacturing method is edited by Katsuo Soga, for example. ELSEVIER, 1990, etc.), U.S. Patent No. 5,296,434, European Patent Application No. 518,237, etc., are now commercially produced by various emulsifiers (US EXXON, BASF, Germany, HOECHST, etc.) have.

Suitable in the range of the melt index of the metalocene catalyst-based propylene copolymer resin suitable for the present invention is 0.2 to 50 g / 10 minutes (measured at 230 DEG C, 2.16 kg by ASTM D 1238-70), preferably 1.0 to 20 g / 10 minutes. If the melt index is less than 0.2g / 10min, the compatibility is poor, and improvement effects on the desired film appearance, strength, and thickness non-uniformity cannot be expected.If it exceeds 50g / 10min, the usability is excellent but the strength of the resin itself is insufficient. As a result, the overall strength of the film may be poor.

The metalocene catalyst-based propylene copolymer resin according to the present invention has excellent mechanical properties and excellent adhesion to polyolefin-based resins, thereby improving compatibility of polypropylene-based resins with high-density polyethylene-based resins. It is thought that the object of the present invention has been reached by exhibiting the effect of reducing the occurrence to improve the appearance of the film, to improve the strength and to increase the mat properties.

The metalocene catalyst propylene copolymer resin may be added in an amount of 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the mixture of the polypropylene resin and the high density polyethylene resin. If the added amount is less than 0.1 part by weight, mechanical compatibility such as tensile strength is poor due to poor compatibility, and process defects such as uneven thickness are likely to occur, and if it is more than 20 parts by weight, mat property may be deteriorated.

It is also possible to add the usual additives, such as a lubricating agent, antioxidant, an antistatic agent, a processing aid, to the polyolefin resin composition mainly containing polypropylene in this invention.

Hereinafter, the method for producing a polypropylene-based matt film of the present invention will be described in more detail.

First, a polypropylene resin, a high density polyethylene resin, a metalocene catalyst-based propylene copolymer resin, and a conventional additive are added to a conventional blender or a mixer at an appropriate mixing ratio, and then mixed. As the mixer, a drum, a dumbler type mixer, a ribbon blender, a Henschel mixer, a super mixer, or the like can be used. Next, the mixed resin composition is introduced into a film forming extruder as it is through a hopper, or kneaded and pelletized through a conventional kneader. Kneading can be appropriately carried out by a conventionally known apparatus, for example, a conventional single screw extruder, a twin screw extruder, a mixing roll, a chestnut mixer, a twin screw kneader, and the like, of which a single screw extruder is preferable.

Film molding is carried out in accordance with a conventional method for producing a biaxially stretched polypropylene film. That is, the pelletized resin composition according to the present invention is introduced into an extruder through a hopper, and the melted resin melt is extruded through a T-die, and then cooled on a cooling roll in a range of about 10 to 60 ° C. to form a disc sheet, followed by forming a glass sheet. Advantageously Uniaxial stretching with a stretching roll in the traveling direction in a range of 2 to 7 times, preferably in a range of 3 to 5 times, at a temperature between the melting point and below the melting point, preferably between 50 ° C and 150 ° C. Is done. The uniaxially stretched film is then biaxially stretched in a range of 2 to 10 times, preferably 4 to 8 times while heating in a tenter under a hot air atmosphere in the range of 120 ° C to 180 ° C, and 100 ° C to 170 ° C for dimensional stability. Preferably, heat treatment is performed at a temperature in the range of 120 ° C. to 160 ° C. to produce a final biaxially stretched polypropylene film. On the other hand, it is also possible to manufacture by a normal simultaneous biaxial stretching method, not depending on a sequential biaxial stretching method as mentioned above.

The polypropylene-based matte film prepared according to the present invention is a breakthrough yarn having excellent appearance, matte and mechanical properties at the same time without any process problems such as thickness unevenness during extrusion processing.

Hereinafter, the present invention will be described in more detail with reference to Examples, and the following Examples are merely specific examples of the present invention, and do not limit or limit the protection scope of the present invention.

(Examples 1 to 7)

Density 0.956 g / cm 3, Melt index 0.04 g in a propylene homopolymer (HF20L, Resin A) of 2.2 g / 10 min (measured at 2.16 kg at 230 ° C. by ASTM D 1238-70). 7.6 g of high density ethylene homopolymer (measured at 190 ° C. and 2.16 kg by ASTM D 1238-70 at 2.16 kg) and melt index as a metalocene catalyst-based propylene copolymer resin The metalocene catalyst-based propylene-ethylene copolymer (trade name NOVOLEN, ethylene content 1.11 mol%, resin C) for 10 minutes (measured at 2.16 kg at 230 DEG C according to ASTM D 1238-70) It was added according to the composition, mixed in a Henschel mixer, and the mixture was kneaded with a single screw kneader and then pelletized.

The pellet-like resin composition was introduced into an extruder through a hopper, melt-extruded at 250 ° C., and cooled to melt the resin melt coming out through a T-die to prepare a disc sheet. The obtained original sheet was stretched 4.5 times at 110 ° C., biaxially stretched 8 times in a tenter under a 170 ° C. hot air, and then heat-treated at 150 ° C. to finally produce a polypropylene-based mat film having a thickness of 20 μm. Tensile strength, cloudyness, glossiness, appearance (degree of occurrence of piscia), processability (degree of defects in process such as thickness nonuniformity), etc. of the manufactured film were evaluated, and the results are shown in Table 2.

(Examples 8 to 10)

As a metalocene catalyst propylene copolymer resin, it is 8.0 g / 10 minutes of metalocene catalyst propylene ethylene copolymers (made by BASF Germany, brand name NOVOLEN, ethylene content 1.49 mol%, resin D), 5.3 g / 10 minutes of meta Rosene catalyst-based propylene-butene-1 copolymer (manufactured by BASF, Germany, trade name NOVOLEN, butene-1 content 1.50 mol%, resin E), metalocene catalyst-based propylene-butene-1 copolymer (Germany BASF) A commercially available product, trade name NOVOLEN, butene-1 content 2.50 mol%, and resin F) were used in the same manner as in Example 3 to prepare a polypropylene-based matt film, and the evaluation results are shown in Table 2.

(Comparative Examples 1 to 3)

The resin composition was added to the above propylene homopolymer (resin A) of 2.20 g / 10 minutes, except that only the high density ethylene homopolymer (resin B) of 0.04 g / 10 minutes of melt index was added in the formulation shown in Table 1. A polypropylene-based mat-like film having a thickness of 20 µm was prepared under the same film forming processing conditions as in Example 1. The evaluation results are shown in Table 2.

The tensile strength, cloudiness, glossiness, appearance (degree of occurrence of piscia), and workability (degree of defects in the process such as thickness nonuniformity) of the polypropylene-based matte films prepared according to the examples and comparative examples are specified as follows. The results are shown in Table 2 below.

(The tensile strength)

According to ASTM D 882, the strength (kg / cm 3) at the time of fracture of the sample was measured in the traveling direction (MD) and in the width direction (TD) perpendicular to the traveling direction (sample size: 150 mm length × 15 mm width, Grip Spacing: 100mm, Tensile Speed: 500mm / min, Measuring Temperature: 23 ± 1 ℃)

(Blur)

As one of the evaluation methods of the matteness, the haze (%) was measured using a haze meter according to ASTM D 1003.

(Glossiness)

As one of the evaluation methods of the matteness, the glossiness (%) was measured under the incident angle of 75 degrees using a glossiness meter in accordance with ASTM D 523.

(Exterior)

The number of fisheye per unit area of the film was relatively evaluated by comparison with that value of a general transparent biaxially oriented polypropylene film.

(Processability)

The extent of defects in processing such as thickness uniformity of the film during extrusion was measured.

TABLE 1

TABLE 2

Claims (4)

0.1 to 20 weight percent of a metalocene catalyst-based propylene copolymer resin based on 100 parts by weight of a resin composition composed of 40 to 80% by weight of polypropylene resin and 60 to 20% by weight of high density polyethylene resin having a density of 0.94 to 0.97 g / cm 3 A polypropylene-based matte film, which is obtained by biaxially stretching an original sheet obtained by extruding a composition to be added. The polypropylene resin according to claim 1, wherein the polypropylene resin is a propylene homopolymer mainly composed of propylene polymerized using a Ziegler-Natta catalyst or a propylene-α-olefin copolymer having a content of 15 mol% or less, An index of 0.01 to 20 g / 10 minutes is polypropylene-based matt film. The ethylene polymer according to claim 1, wherein the high density polyethylene resin has an ethylene homopolymer or α-olefin content of 10 mol% or less mainly based on ethylene polymerized using a Ziegler-Natta catalyst in a density range of 0.94-0.97 g / cm 3. It is a -alpha-olefin copolymer, The polypropylene-type matte film characterized by the melt index of 0.02-20g / 10min. The method of claim 1, wherein the metalocene catalyst-based propylene copolymer resin is a copolymer of propylene and α-olefin polymerized using a metalocene catalyst, the content of α-olefin is 15 mol% or less, the melt index is 0.2 It is -50 g / 10min. Polypropylene-type matte film characterized by the above-mentioned.