KR102404680B1 - Resin compositions of polyethylene used agricultural film and film manufactured by using the same - Google Patents

Abstract

By providing an agricultural polyethylene resin composition comprising a linear low-density polyethylene resin prepared under a Ziegler-Natta catalyst and a linear low-density polyethylene resin prepared under a metallocene-based catalyst, a polyethylene resin with excellent film processability and transparency while having excellent rigidity and strength A composition and a film molded using the same are disclosed. The present invention consists of (A) ethylene and an α-olefin having 4 or more carbon atoms, a Ziegler-Natta system having a density of 0.910 to 0.930 g/cm 3 and a melt index (190° C., 2.16 kg) of 0.1 to 2.0 g/10 min. 70-95% by weight of a linear low-density polyethylene resin prepared under a catalyst; and (B) ethylene and an α-olefin having 6 or more carbon atoms, a density of 0.910 to 0.930 g/cm 3 , a melt index (190° C., 2.16 kg) of 0.1 to 2.0 g/10 min, and a weight average molecular weight of 70,000 ~150,000, molecular weight distribution (Mw / Mn) is 2.8 ~ 5, contains 1 to 3 LCB (Long chain branch) based on molecular weight 10 ⁶ , SCB (Short chain branch) is 10 per 1000 carbons in the main chain It is an agricultural polyethylene resin composition comprising; 5-30 wt% of a linear low-density polyethylene resin prepared under a metallocene-based catalyst containing ~ 30; ℃, 2.16 kg) provides an agricultural polyethylene resin composition of 0.1 to 2.0 g / 10 minutes.

Description

Polyethylene resin composition for manufacturing an agricultural film, and a film prepared using the same

The present invention relates to an agricultural polyethylene resin composition and a film prepared using the same, and more particularly, to a linear low-density polyethylene resin prepared under a Ziegler-Natta catalyst and a linear low-density polyethylene resin prepared under a metallocene-based catalyst. It relates to a polyethylene resin composition and a film prepared using the same.

Agricultural film is a generic term for films used in plastic houses, mulching, silage, and the like. Agricultural films require excellent mechanical strength, transparency and UV protection to accept harmful sunlight inside, and weather resistance to withstand external environmental changes.

Resins used in such agricultural films are mainly polyethylene, ethylene vinyl acetate copolymer, polyvinyl chloride, polycarbonate, and the like. In particular, polyethylene resin is the most used throughout the agricultural field because it has few harmful components for use in agriculture, and has the advantage of being inexpensive while satisfying basic physical properties.

Polyethylene is a general-purpose polymer widely used for various purposes, and is largely classified into high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE) according to its density. In particular, LLDPE is a resin that exhibits a relatively appropriate combination of the flexibility of LDPE and the rigidity of HDPE, and is most often used for film applications. It is used not only for agriculture but also throughout the film industry, such as for industrial use and lamination. In particular, the development of linear low-density polyethylene (mLLDPE) using a metallocene catalyst in the production of raw materials to increase the strength, rigidity, and transparency of the LLDPE film provided an opportunity to advance one step further in the development of the polyethylene film.

However, in the case of using mLLDPE alone, as the extruder load increases and the melt fracture on the film surface increases in film forming, the extrusion amount decreases and the film smoothness decreases. In order to solve this problem, prior patents show a technology of blending HDPE, LDPE, LLDPE and polyethylene using a metallocene catalyst. Although the characteristics are shown, additional improvement and supplementation are needed because the uniformity may be poor in the blending method, or the blending ratio may not be suitable for agricultural film applications.

Korean Patent Application Laid-Open No. 2016-0062727 discloses a technology for manufacturing a film for general packaging by blending mLLDPE and LLDPE. However, as the content of mLLDPE increases, the resin discharge amount and the film surface become unstable according to the extrusion load. There is the problem of additional mixing of LDPE.

Korean Patent Application Laid-Open No. 2015-0028210 discloses a technology for manufacturing a film for vacuum packaging by blending mLLDPE, LLDPE, and LDPE, but the uniformity is poor in the blending method, and molding stability is high because the mLLDPE ratio is high in terms of blending ratio This decreases, and there is a problem that the price competitiveness of the product decreases.

Korean Patent Publication No. 1424857 discloses a technology for manufacturing a film for heavy packaging bags by blending mLLDPE and LLDPE. However, as the content of mLLDPE increases, the resin discharge amount and the film surface become unstable according to the extrusion load. There is a problem of additional mixing.

Korea Patent Publication No. 1019656 discloses a polyolefin resin composition for a film comprising an elastomer, a linear low-density polyethylene prepared with a metallocene catalyst, a low-density polyethylene, an ethylene copolymer prepared with a Ziegler-Natta catalyst, etc. Including 40 to 60% by weight of linear low-density polyethylene prepared with a strong catalyst may cause problems in flowability and film smoothness.

Korean Patent Application Laid-Open No. 2003-0019454 discloses a resin composition blended with LLDPE and mVLDPE and a film using the same, but there is a limit to improving the molding stability and transparency of the film because the uniformity is poor in the blending method. .

Japanese Laid-Open Patent Publication No. 1998-168244 discloses a sealant film for a white box in which LLDPE and mLLDPE are blended, but there is a limit in improving molding stability and transparency because the uniformity is also inferior in the blending method.

The present invention is a resin composition comprising a linear low-density polyethylene resin prepared with a Ziegler-Natta catalyst and a linear low-density polyethylene resin prepared with a metallocene-based catalyst when manufacturing an agricultural film, and has excellent workability and transparency while having excellent rigidity and strength , in particular, to provide a polyethylene resin composition suitable for an agricultural film, a method for manufacturing the same, and an agricultural film produced using the same.

In order to solve the above problems, the present invention is made of (A) ethylene and α-olefin having 4 or more carbon atoms, and has a density of 0.910 to 0.930 g/cm 3 and a melt index (190° C., 2.16 kg) of 0.1 to 2.0 g/ 70-95% by weight of a linear low-density polyethylene resin prepared under a Ziegler-Natta catalyst for 10 minutes; and (B) ethylene and an α-olefin having 6 or more carbon atoms, a density of 0.910 to 0.930 g/cm 3 , a melt index (190° C., 2.16 kg) of 0.1 to 2.0 g/10 min, and a weight average molecular weight of 70,000 ~150,000, molecular weight distribution (Mw / Mn) is 2.8 ~ 5, contains 1 to 3 LCB (Long chain branch) based on molecular weight 10 ⁶ , SCB (Short chain branch) is 10 per 1000 carbons in the main chain It is an agricultural polyethylene resin composition comprising; 5-30 wt% of a linear low-density polyethylene resin prepared under a metallocene-based catalyst containing ~ 30; ℃, 2.16 kg) provides an agricultural polyethylene resin composition of 0.1 to 2.0 g / 10 minutes.

In addition, the (A) linear low-density polyethylene resin contains 1 to 15% by weight of the α-olefin having 4 or more carbon atoms, and the (B) linear low-density polyethylene resin contains 1 to 15% by weight of the α-olefin having 6 or more carbon atoms. It provides an agricultural polyethylene resin composition, characterized in that it comprises a weight %.

In addition, the agricultural polyethylene resin composition (C) has a density of 0.910 ~ 0.930 g / ㎤, a melt index (190 ℃, 2.16 kg) of 0.5 ~ 5.0 g / 10 minutes, the molecular weight distribution curve has a unimodal distribution, high pressure tubular 1 to 15 parts by weight of the low-density polyethylene resin produced by the process based on 100 parts by weight of the resin including (A) and (B); It provides a polyethylene resin composition for agriculture, characterized in that it further comprises.

In addition, as a method for preparing the agricultural polyethylene resin composition of claim 1 by melt blending, the method comprising: (A) introducing a linear low-density polyethylene resin prepared under the Ziegler-Natta catalyst into an extruder; (B) adding the linear low-density polyethylene resin prepared under the metallocene-based catalyst to the side feeder of the extruder; And it provides a method for producing a polyethylene resin composition for agriculture, comprising a; and mixing in a molten state at a temperature of 150 ~ 240 ℃ of the extruder to prepare a polyethylene composition in the form of pellets.

In addition, (C) with the above (B), the density is 0.910 ~ 0.930 g / ㎤, the melt index (190 ℃, 2.16 kg) is 0.5 ~ 5.0 g / 10 minutes, the molecular weight distribution curve has a unimodal distribution, high pressure tubular It provides a method for producing a polyethylene resin composition for agriculture, characterized in that the low-density polyethylene resin produced by the process is put into a side feeder of the extruder.

In addition, it is molded by the air-cooling inflation method from the agricultural polyethylene resin composition, and the Elmendorf tear strength according to ASTM D1922 in the film thickness range of 20 to 80 μm is 5 g/μm or more in the machine direction (MD) and 10 g/μm in the transverse direction (TD) ㎛ or more, the dart impact strength according to ASTM D1709A is 130 g or more, the haze according to JIS K 7361 is 20% or less, and the following UV irradiation provides an agricultural film characterized in that it is 95% or more do.

[Material property retention (%) according to UV irradiation]

Using a weather resistance tester (Atlas, Ci4000), the film is irradiated with ultraviolet rays for 100 hours according to ISO 4892-2, and the tensile properties at break before and after UV irradiation according to ASTM D882 using a universal tensile tester (GALDABINI, QUASAR10) Measure and calculate the ratio as shown in the following formula.

Retention of physical properties = [Physical properties after UV irradiation / Physical properties before UV irradiation] × 100

According to the present invention, by providing an agricultural polyethylene resin composition comprising a linear low-density polyethylene resin prepared under a Ziegler-Natta catalyst and a linear low-density polyethylene resin prepared under a metallocene-based catalyst, film processability and transparency while having excellent rigidity and strength It is possible to provide this excellent polyethylene resin composition, a method for producing the same, and a film molded using the same.

Hereinafter, preferred embodiments of the present invention will be described in detail. In describing the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted. Throughout the specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

The present inventors face the fact that in the prior art to provide a resin composition excellent in film formability while having strength and rigidity when manufacturing an agricultural film using a linear low-density polyethylene resin, the above properties are still not satisfactory, and conduct intensive research As a result, in the case of an agricultural polyethylene resin composition comprising a linear low-density polyethylene resin prepared under a Ziegler-Natta catalyst having specific physical properties and content and a linear low-density polyethylene resin prepared under a metallocene-based catalyst, excellent rigidity and strength It has been found that film formability and transparency are dramatically improved while having the present invention.

Accordingly, according to one aspect of the present invention, (A) is made of ethylene and an α-olefin having 4 or more carbon atoms, and has a density of 0.910 to 0.930 g/cm 3 and a melt index (190° C., 2.16 kg) of 0.1 to 2.0 g/10 70-95% by weight of a linear low-density polyethylene resin prepared under a Bunin Ziegler-Natta catalyst; and (B) ethylene and an α-olefin having 6 or more carbon atoms, a density of 0.910 to 0.930 g/cm 3 , a melt index (190° C., 2.16 kg) of 0.1 to 2.0 g/10 min, and a weight average molecular weight of 70,000 ~150,000, molecular weight distribution (Mw / Mn) is 2.8 ~ 5, contains 1 ~ 3 LCB (Long chain branch) based on molecular weight 10 ⁶ , 10 ~ 30 SCB (Short chain branch) per 1000 carbons An agricultural polyethylene resin composition comprising; 5 to 30% by weight of a linear low-density polyethylene resin prepared under a metallocene-based catalyst containing kg) of 0.1 to 2.0 g/10 min. Disclosed is an agricultural polyethylene resin composition.

Hereinafter, each configuration of the polyethylene resin composition for agriculture according to the present invention will be described in detail.

(A) Linear low density polyethylene resin prepared under Ziegler-Natta system catalyst

The linear low-density polyethylene resin prepared under the Ziegler-Natta catalyst used in the present invention is a copolymer composed of ethylene and an α-olefin having 4 or more carbon atoms, preferably 4 to 20 carbon atoms. Here, in order to satisfy the purpose of maintaining strength and film molding processability and transparency according to the purpose of the agricultural polyethylene resin composition according to the present invention, the α-olefin is contained in an amount of 1 to 15% by weight with respect to the copolymer. Preferably, it is more preferable to contain 3 to 12% by weight.

Examples of the α-olefin include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene, etc. are mentioned.

In addition, when a linear low-density polyethylene resin prepared under a Ziegler-Natta catalyst having a density of 0.910 to 0.930 g/cm 3 is used, a polyethylene resin composition capable of providing a film having excellent strength and rigidity can be obtained. In this case, it is more preferable to use a linear low-density polyethylene resin prepared under a Ziegler-Natta catalyst having a density of 0.915 to 0.925 g/cm 3 .

In addition, when a linear low-density polyethylene resin prepared under a Ziegler-Natta catalyst having a melt index (190°C, 2.16 kg) of 0.1 to 2.0 g/10 min is used, the resin has good extrudability during film forming by the air-cooled inflation method and the film surface This non-rough film can be obtained. In this case, it is more preferable to use a linear low-density polyethylene resin prepared under a Ziegler-Natta catalyst having a melt index of 0.5 to 1.5 g/10 min.

The linear low-density polyethylene resin prepared under the Ziegler-Natta catalyst used in the resin composition of the present invention can be prepared by a conventional method. For example, copolymerization of ethylene with α-olefin having 4 or more carbon atoms under a Ziegler-Natta catalyst may be performed by a gas phase method, and may be prepared using a solution method, a slurry method, or the like.

The (A) linear low-density polyethylene resin prepared under the Ziegler-Natta catalyst is included in an amount of 70 to 95% by weight based on the total content of the linear low-density polyethylene resin prepared under the (B) metallocene catalyst, which will be described later, preferably 75 to 90% by weight may be included. In the above content range, a polyethylene resin composition having good extrudability of the resin and excellent film strength, rigidity, and transparency during film molding by the air cooling inflation method is obtained.

(B) a linear low-density polyethylene resin prepared under a metallocene-based catalyst

The linear low-density polyethylene resin prepared under the metallocene-based catalyst used in the present invention has improved processing characteristics, and has a molecular weight distribution compared to the linear low-density polyethylene resin prepared under the general metallocene catalyst used for conventional industrial and heavy packaging bags. It is wide and has the advantage of excellent processability because LCB (Long chain branch) is partially included in the molecule.

That is, the linear low-density polyethylene resin prepared under the (B) metallocene-based catalyst with improved processability used in the present invention has an LCB content of 1 to 3 based on a molecular weight of 10 ⁶ , and an SCB content of 1,000 carbons (C) It is preferable to include 10 to 30 per sugar.

The SCB (Short chain branch) is a branch attached to the main chain of the olefin-based polymer, and is a branch having 2 to 5 carbon atoms, usually as a comonomer, such as 1-butene, 1-hexene, 1-octene, etc. It means side branches made when an α-olefin having 4 or more carbon atoms is used, and the LCB means a branch having 6 or more carbon atoms.

Always (B) The linear low-density polyethylene resin prepared under the metallocene catalyst is a copolymer composed of ethylene and an α-olefin having 6 or more carbon atoms, preferably 6 to 20 carbon atoms. Here, in order to satisfy the purpose of maintaining strength and film molding processability and transparency according to the purpose of the agricultural polyethylene resin composition according to the present invention, the α-olefin is contained in an amount of 1 to 15% by weight with respect to the copolymer. Preferably, it is more preferable to contain 3 to 12% by weight.

Examples of the α-olefin include 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eico. Sen and the like.

In addition, when a linear low-density polyethylene resin prepared under a metallocene-based catalyst having a density of 0.910 to 0.930 g/cm 3 is used, a polyethylene resin composition capable of providing a film having excellent strength and rigidity can be obtained. In this case, it is more preferable to use a linear low-density polyethylene resin prepared under a metallocene-based catalyst having a density of 0.915 to 0.925 g/cm 3 .

In addition, when a linear low-density polyethylene resin prepared under a metallocene-based catalyst having a melt index (190°C, 2.16 kg) of 0.1 to 2.0 g/10 min is used, the resin has good extrudability and the film is rigid during film forming by the air-cooling inflation method. This excellent film can be obtained. In this case, it is more preferable to use a linear low-density polyethylene resin prepared under a metallocene-based catalyst having a melt index of 0.5 to 1.5 g/10 min.

In addition, the ethylene and α-olefin copolymer preferably has a weight average molecular weight of 70,000 to 150,000, and a molecular weight distribution (Mw/Mn) of 2.8 to 5.0. In the above content range, weight average molecular weight, and molecular weight distribution range, a polyethylene resin composition having good extrudability of the resin and excellent film strength, rigidity, and transparency during film molding by the air cooling inflation method is obtained.

The linear low-density polyethylene resin prepared under the metallocene-based catalyst used in the resin composition of the present invention as described above can be prepared by a conventional method. For example, the copolymerization of ethylene with α-olefin having 6 or more carbon atoms under a metallocene catalyst may be performed as a solution method, and may be prepared using a gas phase method, a slurry method, or the like.

The linear low-density polyethylene resin prepared under the metallocene catalyst with improved processability in the molecular weight distribution and content range of LCB and SCB has superior processing characteristics such as bubble stability, extrusion load, and melt fracture compared to general resins. and excellent transparency.

The linear low-density polyethylene resin prepared under the metallocene-based catalyst is included in 5 to 30% by weight, preferably 10 to 25% by weight, based on the total weight of the linear low-density polyethylene resin prepared under the Ziegler-Natta-based catalyst. In the above content range, a polyethylene resin composition having good extrudability of the resin and excellent film strength, rigidity and transparency is obtained during film molding by the air-cooling inflation method.

(C) low density polyethylene

In the present invention, when applied as an agricultural film through an air-cooling inflation method using the polyethylene resin composition, a low-density polyethylene resin having predetermined physical properties may be further included in a specific content to maximize transparency and tear strength.

In the present invention, the density of the low-density polyethylene is preferably 0.910 to 0.930 g/cm 3 , and more preferably 0.915 to 0.925 g/cm 3 . When the density of the low-density polyethylene is less than 0.910 g/cm 3 , friction properties may be reduced due to excessive stickiness of the product, and if it exceeds 0.930 g/cm 3 , the transparency of the film may be reduced.

In addition, the low-density polyethylene resin may preferably have a melt index (temperature 190° C., 2.16 kg) of 0.5 to 5.0 g/10 min, more preferably 1.0 to 4.0 g/10 min. When the melt index of the low-density polyethylene is less than 0.5 g/10 min, the extrusion load of the film forming machine may be increased, and if the melt index exceeds 5.0 g/10 min, mechanical strength may be reduced.

In addition, the molecular weight distribution curve of the low-density polyethylene has a unimodal distribution. The unimodal molecular weight distribution means that, for the purpose of the present invention, the molecular weight distribution has no inflection point other than the maximum value. If the molecular weight distribution of the low density polyethylene has a distribution with many inflection points such as bimodal or trimodal other than a single rod, (A) the linear low density polyethylene prepared under the Ziegler-Natta catalyst and (B) the linear low density polyethylene resin prepared under the metallocene catalyst Transparency may decrease when blended with

In addition, the low-density polyethylene is preferably manufactured by a high-pressure tubular process, and the low-density polyethylene manufactured by the high-pressure autoclave process may have poor transparency when blended with linear low-density polyethylene.

In the present invention, the low-density polyethylene content ratio is 1 to 15 parts by weight based on 100 parts by weight of the total of (A) the linear low-density polyethylene prepared under the Ziegler-Natta catalyst and (B) the linear low-density polyethylene resin prepared under the metallocene catalyst. It is preferable, and it is more preferable that it is 2-12 weight part. When the content of the low-density polyethylene is less than 1 part by weight, the degree of improvement in transparency and mechanical strength may not be satisfactory, and when it exceeds 15 parts by weight, transparency is improved, but tear strength and impact strength may be rather reduced.

On the other hand, the polyethylene resin composition for agriculture according to the present invention does not impair the purpose of the present invention, as long as necessary, various additives such as antioxidants, antistatic agents, slip agents, antiblocking agents, lubricants, pigments, dyes, plasticizers, antioxidants , a hydrochloric acid absorbent, etc. may be additionally contained at least one type. The amount of each of these additives can be adjusted in consideration of the total production amount and the manufacturing process, etc. within a range known to be usable for manufacturing it without affecting the characteristics of the agricultural polyethylene resin composition according to the present invention. The additives may be additionally added in the step of mixing (A) the linear low-density polyethylene resin prepared under the Ziegler-Natta catalyst and (B) the linear low-density polyethylene resin prepared under the metallocene-based catalyst, a separate additional step It may be added by kneading in

In the present invention, a UV stabilizer may be further included to reinforce physical properties as an agricultural film use, and the UV stabilizer is, for example, among hindered amine-based, triazine-based, piperidine-based, salicylic acid-based, benzophenone-based and benzotriazole-based It may be one or more components selected. In addition, 0.01 to 0.3 parts by weight may be included with respect to 100 parts by weight of the composition including (A) and (B) or (A), (B) and (C). When it is less than 0.01 parts by weight, durability against UV cannot be greatly expressed, and when it exceeds 0.3 parts by weight, the physical properties and transparency of the processed film may be lower than the target required by the present invention.

Agricultural polyethylene resin composition according to the present invention is (A) a linear low-density polyethylene resin prepared under a Ziegler-Natta catalyst having the specific physical properties and content and (B) a linear low-density polyethylene resin prepared under a metallocene-based catalyst, or the above The components (A) and (B) and (C) low-density polyethylene resin can be produced using a conventional polymer mixing method. For example, dry blending may be performed using a tumbler mixer or a Henschel mixer. However, when the film is manufactured through simple dry mixing, it is not easy to express a desired level of physical properties because dispersibility between polyethylene compositions is deteriorated. Therefore, it is preferable to prepare the resin composition through melt blending in order to maximize the dispersion uniformity of the mixed state or the physical properties of the final product.

Therefore, according to another aspect of the present invention, there is provided a method for preparing the polyethylene resin composition by melt blending, the method comprising: (A) introducing a linear low-density polyethylene resin prepared under a Ziegler-Natta catalyst into an extruder; (B) adding the linear low-density polyethylene resin prepared under the metallocene-based catalyst to the side feeder of the extruder; and preparing a polyethylene composition in pellet form by mixing in a molten state at a temperature of 150 to 240° C. of the extruder; a method for producing a polyethylene resin composition for agriculture is disclosed, comprising a.

In addition, (C) with the above (B), the density is 0.910 ~ 0.930 g / ㎤, the melt index (190 ℃, 2.16 kg) is 0.5 ~ 5.0 g / 10 minutes, the molecular weight distribution curve has a unimodal distribution, high pressure tubular The low-density polyethylene resin produced by the process may be fed into a side feeder of the extruder.

In the case of an agricultural film molded by the air-cooling inflation method from the agricultural polyethylene resin composition according to the present invention constituted as described above, the Elmendorf tear strength according to ASTM D1922 in the film thickness range of 20 to 80 μm is 5 g/μm in the machine direction (MD) Above and in the transverse direction (TD) of 10 g / μm or more, the dart impact strength according to ASTM D1709A is 130 g or more, the haze according to JIS K 7361 is 20% or less, and the retention of physical properties according to the following UV irradiation is 95% may be more than

[Material property retention (%) according to UV irradiation]

Using a weather resistance tester (Atlas, Ci4000), the film is irradiated with ultraviolet rays for 100 hours according to ISO 4892-2, and the tensile properties at break before and after UV irradiation according to ASTM D882 using a universal tensile tester (GALDABINI, QUASAR10) Measure and calculate the ratio as shown in the following formula. Retention of physical properties = [Physical properties after UV irradiation / Physical properties before UV irradiation] × 100

Hereinafter, the present invention will be described in more detail through specific examples and comparative examples.

First, the specifications of the main components used in Examples and Comparative Examples of the present invention are as follows. The following SCB and LCB contents were measured using GPC-FTIR (Gel Permeation Chromatography-Fourier Transform Infrared) equipment.

(A) Linear low density polyethylene resin prepared under Ziegler-Natta catalyst

Melt index (190℃, 2.16kg) composed of ethylene and 1-butene (5-10% by weight) is 1.1g/10min, density is 0.921g/cm3, molecular weight distribution (Mw/Mn) is 3.7, SCB content ( EA/1000C) of 18 and LCB content (based on molecular weight of 10 ⁶ ) of 0 were used.

(B) a linear low-density polyethylene resin prepared under a metallocene-based catalyst

Ethylene and 1-hexene (5-10 wt%) prepared from a metallocene catalyst composition in which a metallocene-based catalyst compound that forms LCB on a support and a metallocene-based catalyst compound that does not form LCB on a support are co-supported ) of melt index (190℃, 2.16kg) of 1g/10min, density 0.918g/cm3, molecular weight distribution (Mw/Mn) 3, SCB content (SCB/1000C) 15, LCB content (molecular weight 10 ⁶ standard) of 1 was used.

(B-1) Linear low-density polyethylene resin prepared under a metallocene-based catalyst

Melt index (190°C, 2.16 kg) of ethylene and 1-hexene (5-10 wt%) prepared from a metallocene catalyst composition in which only a metallocene-based catalyst compound that does not form LCB on a support is supported is 1.1 g A copolymer having a /10 min, density of 0.918 g/cm 3 , molecular weight distribution (Mw/Mn) of 2.3, SCB content (EA/1000C) of 15, and LCB content (based on molecular weight of 10 ⁶ ) of 0 was used.

(B-2) Linear low-density polyethylene resin prepared under a metallocene-based catalyst

Melt index (190°C, 2.16 kg) of ethylene and 1-octene (5-10 wt%) prepared from a metallocene catalyst composition in which only a metallocene-based catalyst compound that does not form LCB on a support is supported is 1 g/ For 10 minutes, a copolymer having a density of 0.916 g/cm 3 , a molecular weight distribution (Mw/Mn) of 2.9, an SCB content (EA/1000C) of 15, and an LCB content (based on a molecular weight of 10 ⁶ ) of 0 was used.

(C) low density polyethylene resin

LDPE prepared by a high-pressure tubular process having a melt index (190° C., 2.16 kg) of 3 g/10 min, a density of 0.922 g/cm 3 , and a molecular weight distribution (Mw/Mn) of 4.8 was used.

(D) UV stabilizer

A hindered amine-based UV stabilizer (C944FD, Chimassorb) was used.

Example 1

(A) 90% by weight of linear low-density polyethylene prepared with Ziegler-Natta catalyst, (B) 10% by weight of linear low-density polyethylene resin prepared with metallocene catalyst, (D) UV stabilizer component (A) and (B) mixed resin After adding 0.08 parts by weight based on 100 parts by weight and mixing with a Henschel mixer for 5 minutes, the composition was solidified by extrusion cooling at 210° C. with a 40 mm twin screw extruder to obtain a pellet-like composition. Using the composition, a film was manufactured under the conditions of a molding temperature of 175° C., a die gap of 2.2 mm, an expansion ratio of 2.1 times, and an ice line height of 32 cm through a blown film extrusion molding machine (Φ 50 mm) using the composition.

Example 2

The same method as in Example 1, except that in Example 1 (A) 80 wt% of a linear low-density polyethylene prepared with a Ziegler-Natta catalyst, and (B) 20 wt% of a linear low-density polyethylene resin prepared with a metallocene catalyst was adjusted to prepare a film.

Example 3

The same method as in Example 1, except that in Example 1 (A) 75 wt% of a linear low-density polyethylene prepared with a Ziegler-Natta catalyst, and (B) 25 wt% of a linear low-density polyethylene resin prepared with a metallocene catalyst was adjusted to prepare a film.

Example 4

In Example 1 (A) 80% by weight of a linear low-density polyethylene prepared with a Ziegler-Natta catalyst, (B) 20% by weight of a linear low-density polyethylene resin prepared with a metallocene catalyst, (C) 2% by weight of a low-density polyethylene resin A film was prepared in the same manner as in Example 1, except that parts were further added.

Example 5

In Example 1, (A) 80% by weight of a linear low-density polyethylene prepared with a Ziegler-Natta catalyst, (B) 20% by weight of a linear low-density polyethylene resin prepared with a metallocene catalyst, (C) 5% by weight of a low-density polyethylene resin A film was prepared in the same manner as in Example 1, except that parts were further added.

Example 6

In Example 1 (A) 80% by weight of a linear low-density polyethylene prepared with a Ziegler-Natta catalyst, (B) 20% by weight of a linear low-density polyethylene resin prepared with a metallocene catalyst, (C) 8% by weight of a low-density polyethylene resin A film was prepared in the same manner as in Example 1, except that parts were further added.

Example 7

In Example 1 (A) 80% by weight of a linear low-density polyethylene prepared with a Ziegler-Natta catalyst, (B) 20% by weight of a linear low-density polyethylene resin prepared with a metallocene catalyst, (D) a UV stabilizer component (A) and ( B) A film was prepared in the same manner as in Example 1, except that it was adjusted to 0.3 parts by weight based on 100 parts by weight of the mixed resin, and (C) 5 parts by weight of the low-density polyethylene resin was further added.

Example 8

In Example 1 (A) 80% by weight of a linear low-density polyethylene prepared with a Ziegler-Natta catalyst, (B) 20% by weight of a linear low-density polyethylene resin prepared under a metallocene-based catalyst, (D) 0 parts by weight of a UV stabilizer, (C) A film was prepared in the same manner as in Example 1, except that 5 parts by weight of a low-density polyethylene resin was added.

Example 9

In Example 1 (A) 80% by weight of a linear low-density polyethylene prepared with a Ziegler-Natta catalyst, (B) 20% by weight of a linear low-density polyethylene resin prepared under a metallocene-based catalyst, (D) 0.5 parts by weight of a UV stabilizer, (C) A film was prepared in the same manner as in Example 1, except that 5 parts by weight of a low-density polyethylene resin was added.

Comparative Example 1

(A) 100% by weight of linear low-density polyethylene prepared with a Ziegler-Natta catalyst and 0.08 parts by weight of (D) UV stabilizer component with respect to 100 parts by weight of (A) resin, mixed with a Henschel mixer for 5 minutes, and then 40mm 2 It solidified by extrusion cooling at 210 degreeC with a screw extruder, and the pellet-form composition was obtained. Using the composition, a film was manufactured under the conditions of a molding temperature of 175° C., a die gap of 2.2 mm, an expansion ratio of 2.1 times, and an ice line height of 32 cm through a blown film extrusion molding machine (Φ 50 mm) using the composition.

Comparative Example 2

(C) A film was prepared in the same manner as in Comparative Example 1, except that 5 parts by weight of the low-density polyethylene resin was added in Comparative Example 1.

Comparative Example 3

In Comparative Example 1, (A) adjusted to 80% by weight of the linear low-density polyethylene prepared with the Ziegler-Natta catalyst, (B-1) compared with the exception of adding 20% by weight of the linear low-density polyethylene resin prepared under the metallocene-based catalyst A film was prepared in the same manner as in Example 1.

Comparative Example 4

In Comparative Example 1, (A) adjusted to 80% by weight of the linear low-density polyethylene prepared by the Ziegler-Natta catalyst, and (B-2) compared with the exception of adding 20% by weight of the linear low-density polyethylene resin prepared under the metallocene-based catalyst A film was prepared in the same manner as in Example 1.

Comparative Example 5

In Comparative Example 1, (A) adjusted to 80% by weight of linear low-density polyethylene prepared with a Ziegler-Natta catalyst, (B-2) 20% by weight of a linear low-density polyethylene resin prepared under a metallocene-based catalyst, and (C) low-density polyethylene resin A film was prepared in the same manner as in Comparative Example 1, except that 5 parts by weight was added.

Comparative Example 6

In Comparative Example 1 (A) adjusted to 80% by weight of a linear low-density polyethylene prepared with a Ziegler-Natta catalyst, (B-1) 20% by weight of a linear low-density polyethylene resin prepared under a metallocene-based catalyst, and (C) a low-density polyethylene resin A film was prepared in the same manner as in Comparative Example 1, except that 5 parts by weight was added.

test example

The polyethylene resin compositions and films prepared according to the Examples and Comparative Examples were evaluated by the following method, and the results are shown in Tables 1 and 2 below.

(1) Haze: The haze of each polyethylene film was measured using a haze meter (NDH5000, Nippon Denshi Co., Ltd.) according to JIS K 7361.

(2) Elmendorf tear strength: It was calculated by dividing the value measured according to ASTM D1922 by the thickness of the film.

(3) Dart impact strength: It was calculated by dividing the value measured according to ASTM D1709A by the thickness of the film.

(4) Retention of properties (%) according to UV irradiation: Using a weather resistance tester (Atlas, Ci4000), irradiate the film with ultraviolet rays for 100 hours according to ISO 4892-2, and use a universal tensile tester (GALDABINI, QUASAR10). According to ASTM D882, the tensile properties at break before and after UV irradiation were measured to calculate the ratio as shown in the following formula.

Retention of physical properties = [Physical properties after UV irradiation / Physical properties before UV irradiation] × 100

(5) Processability: When the film is manufactured using a blown film extrusion molding machine (Φ50mm) at a molding temperature of 175°C, a die gap of 2.2mm, an expansion ratio of 2.1 times, and an ice line height of 32cm, bubble stability, die Processability such as line occurrence was sensory evaluated. (Very good: ◎, Excellent: ○, Normal: △, Poor: X)

Referring to Tables 1 and 2, when (A) the linear low-density polyethylene resin prepared under the Ziegler-Natta catalyst includes the linear low-density polyethylene resin prepared under the metallocene-based catalyst (B) with improved processability (Examples 1 to 3) (B) It can be seen that as the content increases, the haze decreases and the strength increases.

In addition, when (C) low-density polyethylene resin is added to the resin including (A) and (B) (see Examples 4 to 7) (C) As the content increases, the strength decreases, but the haze decreases and processability is improved it can be seen that

In addition, (D) looking at the effect of the addition of the UV stabilizer (see Examples 7 to 9) (D) when the content increases, the retention (%) of physical properties after UV exposure is improved, but it can be seen that other physical properties are lowered.

On the other hand, (A) when (C) was added alone to the linear low-density polyethylene resin prepared under the Ziegler-Natta catalyst (Comparative Example 2), although the haze was somewhat reduced, it can be seen that there is little effect of improving the strength.

In addition, it can be seen that (A) when (B-1) was added alone to the linear low-density polyethylene resin prepared under the Ziegler-Natta catalyst (Comparative Example 3), the strength was improved, but the haze increased and the workability was reduced.

In addition, it can be seen that (A) when (B-2) was added alone to the linear low-density polyethylene resin prepared under the Ziegler-Natta catalyst (Comparative Example 4), the strength was improved, but the haze increased and the workability was reduced.

In addition, (A) when (B-1) and (C) were added in combination to the linear low-density polyethylene resin prepared under the Ziegler-Natta catalyst (Comparative Example 5), the strength was improved, but the haze increased and the workability was reduced Able to know.

In addition, (A) when (B-2) and (C) were added in combination to the linear low-density polyethylene resin prepared under the Ziegler-Natta catalyst (Comparative Example 6), the balance of physical properties including haze and processability showed that the processability according to the present invention was It can be seen that it is inferior to Example 5 in which the improved (B) is combined.

The preferred embodiment of the present invention has been described in detail above. The description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains will understand that other specific forms can be easily modified without changing the technical spirit or essential features of the present invention.

Accordingly, the scope of the present invention is indicated by the following claims rather than the description of the invention, and all changes or modifications derived from the meaning, scope, and equivalent concept of the claims are interpreted as being included in the scope of the present invention. should be

Claims (6)

(A) prepared under a Ziegler-Natta catalyst consisting of ethylene and an α-olefin having 4 or more carbon atoms, a density of 0.910 to 0.930 g/cm 3 and a melt index (190 ° C. 2.16 kg) of 0.1 to 2.0 g/10 min. 70-95% by weight of a linear low-density polyethylene resin;
(B) Consists of ethylene and α-olefin having 6 or more carbon atoms, has a density of 0.910 to 0.930 g/cm 3 , a melt index (2.16 kg at 190° C.) of 0.1 to 2.0 g/10 min, and a weight average molecular weight of 70,000 to 150,000 , molecular weight distribution (Mw/Mn) is 2.8 to 5, and contains 1 to 3 LCB (Long chain branch) based on molecular weight of 106, and 10 to 30 SCB (Short chain branch) per 1000 carbons in the main chain 5-30 wt% of a linear low-density polyethylene resin prepared under a metallocene-based catalyst comprising; and
(C) A low density polyethylene resin having a density of 0.910 to 0.930 g/cm 3 , a melt index (190° C. 2.16 kg) of 0.5 to 5.0 g/10 min, a molecular weight distribution curve having a unimodal distribution, and a high pressure tubular process 1 to 15 parts by weight based on 100 parts by weight of the resin containing (A) and (B);
It is an agricultural polyethylene resin composition comprising a,
The agricultural polyethylene resin composition has a density of 0.910 to 0.930 g/cm 3 and a melt index (190° C. 2.16 kg) of 0.1 to 2.0 g/10 min,
The agricultural use is for a plastic house, mulching or silage film,
Films with a thickness ranging from 20 to 80 μm formed by the air cooling inflation method from the agricultural polyethylene resin composition have an Elmendorf tear strength according to ASTM D1922 of 5 g/μm or more in the machine direction (MD) and 10 g/μm in the transverse direction (TD) ㎛ or more, the dart impact strength according to ASTM D1709A, characterized in that 130g or more agricultural polyethylene resin composition. The method of claim 1,
The (A) linear low-density polyethylene resin comprises 1 to 15% by weight of the α-olefin having 4 or more carbon atoms,
The (B) linear low-density polyethylene resin is an agricultural polyethylene resin composition, characterized in that it contains 1 to 15% by weight of the α-olefin having 6 or more carbon atoms. The method of claim 1,
The resin composition further comprises (D) 0.01 to 0.3 parts by weight of the UV stabilizer based on 100 parts by weight of the resin including (A) and (B);
The film having a thickness of 20 to 80 μm molded by the air cooling inflation method from the agricultural polyethylene resin composition has a haze according to JIS K 7361 of 20% or less, and the retention of physical properties according to the following UV irradiation is 95% or more Agricultural polyethylene resin composition characterized by:
[Material property retention (%) according to UV irradiation]
Using a weather resistance tester (Atlas, Ci4000), the film is irradiated with ultraviolet rays for 100 hours according to ISO 4892-2, and the tensile properties at break before and after UV irradiation according to ASTM D882 using a universal tensile tester (GALDABINI, QUASAR10) Measure and calculate the ratio as shown in the following formula.
Retention of physical properties = [Physical properties after UV irradiation / Physical properties before UV irradiation] × 100 As a method for producing the polyethylene resin composition for agriculture of claim 1 by melt mixing (Melt Blend),
(A) introducing the linear low-density polyethylene resin prepared under the Ziegler-Natta catalyst into an extruder; (B) adding the linear low-density polyethylene resin prepared under the metallocene-based catalyst to the side feeder of the extruder; and preparing a polyethylene composition in pellet form by mixing in a molten state at a temperature of 150 to 240° C. of the extruder. 5. The method of claim 4,
(C) with the above (B), the density is 0.910 ~ 0.930 g / ㎤, the melt index (190 ℃, 2.16 kg) is 0.5 ~ 5.0 g / 10 min, the molecular weight distribution curve has a unimodal distribution, high pressure tubular process A method for producing a polyethylene resin composition for agriculture, characterized in that the low-density polyethylene resin produced by the input to the side feeder (Side feeder) of the extruder. An agricultural film molded by the air cooling inflation method from the agricultural polyethylene resin composition of any one of claims 1 to 3.