KR101309389B1 - Polyethylene resin composition for Heat shrinkage film and Heat shrinkage film - Google Patents

Abstract

The present invention relates to a polyethylene resin composition for heat-shrinkable film and a heat-shrinkable film, more specifically, 20 to 80 parts by weight of metallocene linear low density polyethylene and 80 to 20 parts by weight of low density polyethylene with respect to 100 parts by weight of polyethylene resin composition for heat-shrinkable film. Including, the metallocene linear low density polyethylene is prepared using a metallocene catalyst comprising a cross-linked bisdenyl-based component, the polyethylene resin composition for heat shrink film having a DRI (Dow Rheology Index) index defined by the following formula 5 or more And a heat shrink film.
[Relation 1]
Doh Rheology Index (DRI) = [3.65x10 ⁶ (τ ₀ / η ₀ ) -1] / 10
τ ₀ : characteristic relaxation time, sec
η ₀ : zero-shear viscosity, poise

Description

Polyethylene resin composition for heat shrink film and heat shrink film

The present invention relates to a polyethylene resin composition for a heat shrinkable film and a heat shrinkable film prepared therefrom.

Heat-shrinkable film refers to a film used for the packaging of products by inducing shrinkage in one or both directions of the film by a constant temperature of heat, and for the protection of products, the protection of individual products during packaging and the identification of loaded products, manual and It is widely used for the convenience of automatic transfer. Such a shrink film is generally produced by a blown film forming method and stretched in the machine direction (MD) and transverse direction (TD) during cooling to produce a stress-cooled film. Such a film is used in a shrink wrapping process to package a product to be packaged, and then induce stress relaxation through heat treatment, and consequently shrinkage occurs. Shrinkage rate in MD and TD directions required for product packaging is different and accordingly, the desired shrinkage rate can be achieved by adjusting the draw down ratio (DDR) and blown up ratio (BUR) during blown film forming. have. DDR is a value obtained by dividing the die gap by the product of the film thickness and the expansion ratio, which affects the properties of the MD direction. As the DDR increases, the MD direction increases and the shrinkage in the MD direction increases. BUR is the value of blown bubble divided by die diameter, which affects the physical properties in the TD direction (horizontal direction). As the BUR increases, the shrinkage rate in the TD direction increases. BUR and DDR are the control parameters for blown film forming. Typically, BUR runs between 2.0 and 3.0 and DDR runs between 10 and 50.

Currently, the most widely used shrink film is Low Density Polyethylene (LDPE), which has a melt index of 0.4-0.7 g / 10 min for LDPE manufactured in an autoclave reactor, and a melt index for LDPE produced in a tubular reactor. Resin of 0.2-0.3 g / 10min is mainly used. Shrink films made from these LDPE resins exhibit very good shrinkage properties, enabling thermal shrinkage at low temperatures, high shrinkage rates, and high holding forces.

However, LDPE has a high frequency of pinholes during heat shrinkage, which makes it difficult to reduce the film thickness, and mechanical properties such as tensile force, puncture, and tear property are inferior to those of other resins. The industry manufactures shrink film using linear low density polyethylene (LLDPE) or high density polyethylene (HDPE) to compensate for these characteristics, but when LLDPE or HDPE is mixed with LDPE to improve mechanical properties In particular, in the case of the transverse direction (TD), the phenomenon occurs that expansion rather than contraction occurs. This swelling can lead to loose packaging, leading to product packaging defects, leading to downtime and reduced productivity of the continuous packaging process.

An object of the present invention for solving the above problems, while exhibiting excellent mechanical properties compared to the heat shrink film made of low-density polyethylene (LDPE) alone while preventing the expansion of the transverse direction (TD) in the heat shrink process and induces shrinkage excellent shrinkage characteristics It is providing the polyethylene resin composition for heat shrink films shown and the heat shrink film manufactured by this.

Aspects of the present invention for solving the above problems,

For 100 parts by weight of polyethylene resin composition,

20 to 80 parts by weight of metallocene linear low density polyethylene and

80 to 20 parts by weight of low density polyethylene,

The metallocene linear low density polyethylene is made of a metallocene catalyst and relates to a polyethylene resin composition for a heat shrinkable film having a DRI (Dow Rheological Index) index of 5 or more.

[Relationship 1]

Dow Rhythm Index (DRI) = [3.65x10 ⁶ (τ ₀ / η ₀ ) -1] / 10

τ ₀ : characteristic relaxation time, sec

η ₀ : zero-shear viscosity, poise

The metallocene linear low density polyethylene may have a shear thinning index value of 10 or more represented by the following formula.

[Relation 2]

Shear Thinning Index (STI) = η ₀ / η ₁₀₀

η ₀ : complex viscosity at frequency 0.1 rad / sec

η ₁₀₀ : complex viscosity at frequency 100 rad / sec

The metallocene catalyst may be represented by the following Chemical Formula 1.

[Formula 1]

(THI) ₂ RMQp

In Formula 1,

Two THI ligands are the same or different and are tetrahydroindenyl or a derivative thereof unsubstituted or substituted by a substituent,

The substituents are phenyl (Ph), benzyl (Bz), naphthyl (Naph), indenyl (Ind), benzindenyl (BzInd), methyl (Me), ethyl (Ethyl), n-propyl (n-Pr) , i-propyl (i-Pr), n-butyl (n-Bu), t-butyl (t-Bu), trimethylsilicon group (Me ₃ Si), alkoxy, cycloalkyl and halogen That's it,

R is a structural crosslink that imparts steric stiffness between two THI ligands, and is an alkylidene group, alkylenyl group, germanium group, silicon group, siloxane group, alkylphosphine group or amine group containing 1 to 20 carbon atoms. ,

M is a transition metal of group IIIB, IVB, VB or VIB,

Q is a hydrocarbyl group or halogen having 1 to 20 carbon atoms,

p is 1-4.

Another aspect of the present invention relates to a heat shrink film made of the polyethylene resin composition.

The present invention can apply a metallocene linear low density polyethylene resin having a high long chain branch to a heat shrink film to enhance the mechanical properties compared to a heat shrink film made of conventional LDPE to realize a thin film. In addition, it is possible to provide excellent shrinkage characteristics to prevent expansion in the TD direction and induce shrinkage in the heat shrink process.

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

The present invention provides a polyethylene resin composition for a heat shrink film. The polyethylene resin composition includes a metallocene linear low density polyethylene resin and low density polyethylene.

The metallocene linear low density polyethylene is prepared by copolymerizing ethylene and alpha-olefin in a gas phase polymerization reactor using a metallocene catalyst including a crosslinked bisdenyl group-based component, and a linear low density polyethylene prepared by a general Ziegler-Natta catalyst. In contrast, the long chain branch (LCB) has a high content of long chain branch (LCB) when mixed with low-density polyethylene can improve the mechanical properties and shrinkage properties while preventing the expansion of the TD direction in the heat shrink process of the film.

More specifically, the linear low density polyethylene is a fluidized bed of a composition for polymerization comprising ethylene, comonomer and hydrogen in the presence of a catalyst system comprising a metallocene catalyst comprising a crosslinked bisdenyl-based component represented by the following formula (1) It is prepared by gas phase polymerization by injection into a reactor.

 [Formula 1]

(THI) ₂ RMQp

(In the formula 1,

The two THI ligands are the same or different from each other and are tetrahydroindenyl or a derivative thereof unsubstituted or substituted by a substituent, the substituent being phenyl (Ph), benzyl (Bz), naphthyl (Naph), indenyl ( Ind), benzindenyl (BzInd), methyl (Me), ethyl (Ethyl), n-propyl (n-Pr), i-propyl (i-Pr), n-butyl (n-Bu), t-butyl (t-Bu), a trimethylsilicon group (Me ₃ Si), alkoxy, cycloalkyl, and at least one selected from the group consisting of halogen,

R is a structural bridge that imparts steric rigidity between the two THI ligands and is an alkylidene group, alkylenyl group, germanium group, silicon group, siloxane group, alkylphosphine group or amine group containing 1 to 20 carbon atoms ego,

M is a transition metal of group IIIB, IVB, VB or VIB,

Q is a hydrocarbyl group having from 1 to 20 carbon atoms or halogen,

P is 1 to 4.)

Preferably, the metallocene catalyst is Et (THI) ₂ ZrCl ₂ , Me ₂ Si (THI) ₂ ZrCl ₂ , Me ₂ Si (2-MeTHI) ₂ ZrCl ₂ , Et (2-MeTHI) ₂ ZrCl ₂ , Me ₂ Si (2-Me, 4-PhTHI) ₂ ZrCl ₂ , Et (2-Me, 4-PhTHI) ₂ ZrCl ₂ , Me ₂ Si (2-Me, 4-NaphTHI) ₂ ZrCl ₂ , Et (2-Me , 4-NaphTHI) ₂ ZrCl ₂ , Me ₂ Si (2-Me, 4,5-BzIndTHI) ₂ ZrCl ₂ , and Et (2-Me, 4,5-BzIndTHI) ₂ ZrCl ₂ It may be one or more selected from the group consisting of, but is not limited thereto.

The metallocene catalyst may be used as a supported catalyst supported on a carrier. The carrier may be a solid particulate porous or inorganic material, for example an oxide of silicon or aluminum, preferably the carrier is an inorganic material of spherical particles, for example spherical particles obtained by a spray drying method. It may be a silica present in the form of.

The support of the metallocene catalyst is made by reacting a mixed solution of metallocene and methylaluminoxane on a carrier according to a general method known in the art. Preferably, the molar ratio of the transition metal in aluminum to metallocene is 100: 1 to 300: 1, the reaction temperature is 80 ° C to 120 ° C, and the reaction time may be 1 hour to 2 hours.

For example, to suspend silica in a hydrocarbon solution and to produce an activated catalyst, the metallocene catalyst component is reacted with a methylaluminoxane solution to prepare a solution of the corresponding metallocene cation and anionic methylaluminoxane oligomer. . The resulting solution is added dropwise to the silica suspension solution, and then the mixture is heated to heat for a predetermined time to carry out the supporting reaction. The reaction mixture is then cooled to room temperature and washed and dried three times with hydrocarbon solution under nitrogen to prepare a supported catalyst.

In the gas phase polymerization reaction using the supported catalyst, a promoter may be further used, and the promoter may be an alkylaluminum compound, aluminoxane, modified aluminoxane, aluminate salt, neutral ionizer, ionic ionizer, noncoordinating anion, or non-coordination. It may be at least one selected from the group consisting of Group 13 metal, metalloid anion, borane compound, and borate.

The promoter may be used in a molar ratio of 100 to 1000 with respect to the transition metal of the metallocene catalyst.

The hydrogen may be used in a molar ratio of 0.0001 to 0.001 for the ethylene to control the melt index of the polymer during polymerization. The comonomer may be used in a molar ratio of 0.001 to 0.02 relative to the ethylene to control density, and the comonomer may be an alpha-olefin monomer having 2 to 20 carbon atoms.

The gas phase polymerization temperature in the kerosene reactor is preferably 70 ~ 80 ℃, the operating pressure in the fluidized bed reactor may be preferably 10 to 30 atm.

The metallocene linear low density polyethylene contains a long chain branch, which can be measured by the DRI (Dow Rheology Index) method. The Doh Rheology Index (DRI) is defined as the degree of deviation of the rheological properties of polyolefins with a long chain branch (LCB) from the rheological behavior of linear polyolefins (S.Lai, Dow rheology index (DRI) for insite technology polyolefins (ITP): unique structure-processing relationship [ANTEC, p1814 (1994)].

More specifically, the rheology of the metallocene linear low density polyethylene resin is the following relationship is established.

[Relationship 1]

η ₀ = 3.65 x 10 ⁶ (τ ₀ )

Where τ ₀ is the characteristic relaxation time (sec) and η ₀ is the zero-shear viscosity (poise), which is the rheological characteristic of the individual resin.

The DRI means a degree deviating from the relation 1 and calculated from the relation 2 below.

[Relation 2]

DRI = [3.65x10 ⁶ (τ ₀ / η ₀ ) ^-1 ] / 10

τ ₀ : characteristic relaxation time, sec)

η ₀ : zero-shear viscosity, poise

From the above equation, the DRI value of the linear polyolefin without LDB is "0", and the DRI value increases with increasing LCB.

The metallocene linear low density polyethylene resin according to the present invention may exhibit a DRI value of 5 or higher than a general linear polyethylene resin, and the higher the DRI value, the higher the LDB content, and the higher the LDB content, the larger the shrinkage of the film. Properties can be improved. When the DRI value is 5 or more, the LCB content is high, and thus, when mixed with LDPE, it may prevent the expansion of the heat shrinkable film in the TD direction and exhibit high shrinkage rate while improving mechanical properties.

In the metallocene linear low density polyethylene, the shear thinning index value represented by the following Equation 3 may be 10 or more. The shear thinning index is an index for indirectly measuring whether or not LCB is contained. The higher the value, the higher the LCB content. If the shear thinning index is 10 or more, the TD direction of the heat shrinkable film is improved while improving the mechanical properties of the heat shrinkable film. To prevent swelling and exhibit high shrinkage.

[Relation 3]

Shear Thinning Index (SHI) = η ₀ / η ₁₀₀

η ₀ : complex viscosity at frequency 0.1 rad / sec

η ₁₀₀ : complex viscosity at frequency 100 rad / sec

The melt index (ASTM D1238) of the metallocene linear low density polyethylene may be 0.3 to 1.2, and the density (ASTM D1505) may be 0.923 to 0.932.

In the polyethylene resin composition, the metallocene linear low density polyethylene is included in an amount of 20 to 80 parts by weight based on 100 parts by weight of the polyethylene resin composition, and the low density polyethylene is included in an amount of 80 to 20 parts by weight based on 100 parts by weight of the polyethylene resin composition. When the metallocene linear low density polyethylene and the low density polyethylene are included in the above range, it is possible to provide a heat shrinkable polyethylene film that provides excellent mechanical properties and shrinkage rate and that can be performed without expansion in the transverse direction (TD) direction in the heat shrink process.

Low-density polyethylene in the polyethylene resin composition can be used without limitation as long as it is applied to the heat-shrinkable polyethylene film, it is not particularly limited in the present invention.

The present invention provides a heat shrinkable polyethylene film made of the polyethylene resin composition.

The polyethylene film may use a metallocene linear low density polyethylene resin having high long chain branching to improve shrinkage reduction and TD direction expansion of the film generated when the existing linear low density polyethylene is applied.

The polyethylene film has a coefficient of expansion in the transverse direction (TD) direction of less than 7% during the heat shrink process.

Hereinafter, the present invention will be described in more detail with reference to the following examples and comparative examples so that those skilled in the art can easily practice the present invention. The following examples are merely examples for illustrating the present invention, and do not limit the protection scope of the present invention.

 [ Manufacturing example  1] activated Metallocene  Preparation of the catalyst

The carrier used Grace's XPO-2402 (average particle size 50 microns, surface area 300 m ² / g, micropore volume 1.6 cc / g, OH concentration 1 mmol / g) dehydrated silica. 5 g of the silica was suspended in 25 ml of toluene in a round bottom flask equipped with a magnetic stirrer, nitrogen inlet and dropping funnel.

To produce an activated metallocene catalyst, about 0.3 g of Et (THI) ₂ ZrCl ₂ (manufactured by mCAT, Germany) and 75 ml of methylaluminoxane (10% by weight of MAO in toluene) were added at a temperature of 25 ° C. The reaction was carried out for a minute to yield a solution of the metallocene cation and anionic methylaluminoxane oligomer. The molar ratio of metallocene catalyst to methyl aluminoxane is 164.

The solution containing the resulting metallocene cation and anionic methylaluminoxane oligomer was immediately replaced by a reflux condenser under nitrogen and then added dropwise with a funnel to the suspended silica. The mixtures were each heated to 110 ° C. for 90 minutes. The reaction mixture was then cooled to room temperature, filtered under nitrogen and washed with toluene. The resulting catalyst system was then washed with pentane and then dried under mild vacuum to give an activated metallocene catalyst.

 [ Manufacturing example  2] Preparation of Linear Low Density Polyethylene Resin

Inserting the metallocene catalyst prepared in the fluidized bed reactor, and the polymerization composition containing ethylene, comonomer and hydrogen under the polymerization conditions of Table 1 is injected into the fluidized bed reactor and then gas phase polymerization to prepare a linear low density polyethylene resin , Physical properties were measured. The results are shown in Table 2.

Item unit Resin1 Resin2 Resin3 polymerization
Condition Polymerization temperature ℃ 80 80 80 Polymerization pressure kg / cm ² 19.2 19.2 19.2 Flow line velocity cm / sec 25 25 25 Residence time hr 10 10 10 Ethylene (C ₂ ) mol% 50 50 50 Hydrogen (H ₂ ) mol% 0.01 0.02 0.04 1-Hexene mol% 0.15 0.15 0.15 basic
Properties MI g / 10 min 0.35 0.5 0.7  Density g / cc 0.928 0.928 0.928

Item unit Resin1 Resin2 Resin3 HS1100 ¹⁾ 5301 ²⁾ Melt Index (MI) g / 10 min 0.35 0.5 0.7 0.7 0.3 density g / cm ³ 0.928 0.928 0.928 0.928 0.921 MFRR (MI ₂₁ / MI ₂ ) - 38 36 39 29 27 Molecular weight distribution - 3.1 3.4 3.4 3.8 9.0 η ₀ poise 5.0 x 10 ⁶ 1.4 x 10 ⁶ 6.7 x 10 ⁶ 1.4x10 ⁵ 5.3 x 10 ⁴  STI - 16.1 12.8 11.9 6.0 8.8 DRI - 7.8 10.5 10.4 0.5 2.7 ³⁾

1): Hanwha LLDPE Co., Ltd. (product name HS1100) is a 1-Hexene / Ethylene copolymer prepared using Ziegler catalyst.

2): Hanwha LDPE Co., Ltd. (Product Name 5301).

3): The DRI value is an index comparing the long chain content characteristics of linear polyethylene (LLDPE), so the LDPE value is not comparable.

Referring to Table 2, it can be seen that the linear low density polyethylene prepared with the metallocene catalyst of the present invention exhibits higher SHI and DRI values than that of Ziegler-Natta based linear low density polyethylene. This is a characteristic factor that helps to express good shrinkage properties similar to LDPE in shrinkage heat treatment processes.

Example  One

(1) polyethylene resin composition

Hanwha 5301 was used as low density polyethylene (LDPE) and Resin 1 was used as linear low density polyethylene. Resin 1 is a linear low density polyethylene made of a metallocene catalyst as mentioned above with a MI of 0.35 and a density of 0.928. The two resins were blended at a mixing ratio of 80:20.

(2) Blown  Manufacture of film

A blown film was produced at a processing temperature of 190 ° C. and a screw rotation speed of 50 rpm using a 50 mmΦ screw, a die diameter of 100 mm, and a die gap of 2.5 mm. The BUR was 2.0, the film thickness was 60 μm, and the DDR was 20.8. After preparing the film, physical properties were measured by the following method, and shrinkage was measured at 100 ° C., 110 ° C., 120 ° C., 125 ° C., and 130 ° C. using an oil bath. The results are shown in Tables 3-5.

Example  2 to 6

A polyethylene resin composition and a film were prepared in the same manner as in Example 1 except that the components as shown in Table 3 were prepared, and the physical properties thereof were measured. The results are shown in Tables 3-5.

Comparative example  One

As shown in Table 3, except that the HS1100 was used, a polyethylene resin composition and a film were prepared in the same manner as in Example 1, and physical properties were measured. The results are shown in Tables 3-5.

Resin  And measuring properties of the film

(1) melt index ( Melt flow Index )

Melt index was measured at 230 ° C. and 2.16 kg under the conditions of ASTM D1238.

(2) density

Density was measured in the measurements in the Density Gradient Column by ASTM D1505 method.

(3) MFRR ( Melt flow rate ratio )

MFRR was calculated as the ratio of the melt index (MI ₂₁ / MI ₂ ) under 190 ° C, 21.6 kg (MI ₂₁ ) and 2.16 kg (MI ₂ ) loads.

(4) Molecular weight distribution

Molecular weight distribution is the weight average molecular weight measured from GPC (Gel Permeation Chromatography). It was calculated as the ratio (Mw / Mn) of (Mw) and number average molecular weight (Mn).

(5) Zero shear viscosity

Zero shear viscosity was calculated by measuring dynamic fluidity data using a frequency sweep (Frequency Sweep) method at a temperature of 190 ℃ using a rheometric ARES rheometer. The spacing in the parallel plate structure is 2 mm, the plate diameter is 25 mm and the strain amplitude is 10%. Frequency was measured in the range 0.05 ~ 300 rad / sec. Zero shear viscosity was calculated using the Carraeu Model.

 (6) Shear thinning index ( STI )

The shear thinning index was calculated from the ratio of complex viscosity at frequency 0.1 rad / sec and complex viscosity at frequency 100 rad / sec measured from ARES.

 (7) DRI ( Dow Rheology  index)

DRI calculates τ ₀ (characteristic relaxation time, sec) and η ₀ (zero-shear viscosity, poise) using the cross model from the data measured from ARES, and then DRI = [3.65x10 ⁶ (τ _0). / η ₀ ) -1] / 10.

(8) Contraction ratio  Measure

10 cm X 10 cm was taken from the prepared film, the film was immersed in an oil bath at a constant temperature, and then taken out after 20 seconds, and then the lengths of the MD and TD directions were measured after cooling to room temperature. Shrinkage was calculated as follows.

Shrinkage (%) = 100-(Lo Lt) / Lo

Lo: Length before contraction

Lt: length after shrink

Configuration
Comparative example Example One One 2 3 4 5 6
Suzy LLDPE Kinds HS1100 Resin1 Resin2 Resin3 Resin1 Resin2 Resin3 content 20% 20% 20% 20% 50% 50% 50% LDPE content 80% 80% 80% 80% 50% 50% 50% Film properties Motor load Ampere 50 rpm 35 35 35 35 40 45 37 Resin pressure kg / cm ² 513 520 512 496 580 540 518 Extrusion amount g / 4min 1496 1486 1506 1521 1486 1484 1536 Seal kgf / cm ² MD 341 344 338 327 406 393 349 TD 283 286 264 263 359 329 325 Elongation % MD 250 285 295 330 450 355 480 TD 250 710 700 680 785 750 750 Tear kgf / cm MD 118 113 100 108 121 133 114 TD 131 131 116 125 159 150 149 Modulus kgf / cm ² MD 613 1116 654 759 824 784 620 TD 1451 1357 1483 1471 1570 1499 1488 Puncture N 72 71 70 72 71 72 73 F.D.I. g 161 206 176 206 206 176 236

Referring to the results of Table 3, the comparative example of mixing 20% of the linear low density polyethylene prepared with the metallocene catalyst of the present invention and the comparative example of mixing the general linear low density polyethylene at 20% ratio with LDPE Mechanical properties are shown. In addition, when the content of the linear low density polyethylene prepared by the metallocene catalyst is increased to 50%, it can be seen that the physical properties are greatly improved.

MD direction shrinkage Temperature Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 100 1.3 1.0 1.3 0.7 0.0 0.0 0.0 110 17.0 12.0 11.3 10.3 4.5 1.5 2.0 120 40.8 51.0 55.8 36.0 30.5 26.0 40.0 125 57.1 63.5 66.2 58.0 53.4 50.7 57.7 130 73.5 76.0 76.7 76.0 76.3 75.3 75.3

TD direction shrinkage Temperature Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 100 -1.0 0.0 -1.0 -0.8 0.0 0.0 0.0 110 -1.0 -0.5 -1.0 0.0 0.0 0.0 0.0 120 -6.5 -6.5 -6.0 0.7 -0.5 0.0 0.0 125 -2.8 0.2 -1.4 5.6 2.7 1.7 4.3 130 1.0 9.5 6.7 10.5 6.0 3.3 8.7

Note: A negative value indicates expansion.

Tables 4 and 5 show the shrinkage values of the Examples and Comparative Examples. In the shrinkage ratio in the MD direction, in Examples 1, 2, and 3, in which the same ratios were mixed, in Examples 4, 5, and 6, which exhibited the same or higher shrinkage ratios and mixed 50%, the levels similar to those of the comparative examples were obtained. The shrinkage rate is shown. In the shrinkage rate in the TD direction, all the examples showed a higher shrinkage rate than the comparative example, and in particular, in the case of Example 3 and 50% of the mixture, all of them showed only shrinkage without expansion in the contraction temperature section, thereby confirming that the object of the present invention was achieved.

The present invention improves the mechanical properties compared to the existing low density polyethylene film by applying a metallocene linear low density polyethylene to the low density polyethylene, while maintaining the shrinkage in the MD direction during the heat shrinkage process to prevent expansion in the TD direction and induces shrinkage It can provide shrinkage characteristics.

Claims (7)

About 100 weight part of polyethylene resin compositions for heat shrink films,
20 to 80 parts by weight of metallocene linear low density polyethylene and
80 to 20 parts by weight of low density polyethylene,
The metallocene linear low density polyethylene is manufactured using a metallocene catalyst including a crosslinked bisdenyl group-based component, and has a DRI (Dow Rheology Index) index defined by the following formula: Composition:
[Relation 1]
Doh Rheology Index (DRI) = [3.65x10 ⁶ (τ ₀ / η ₀ ) -1] / 10
τ ₀ : characteristic relaxation time, sec
η ₀ : zero-shear viscosity, poise
The method of claim 1,
The metallocene linear low density polyethylene is a polyethylene resin composition for a heat shrinkable film, characterized in that the shear thinning index value is 10 or more:
[Relationship 2]
Shear Thinning Index (STI) = η ₀ / η ₁₀₀
η ₀ : complex viscosity at frequency 0.1 rad / sec
η ₁₀₀ : complex viscosity at frequency 100 rad / sec
The method of claim 1,
The metallocene catalyst is a polyethylene resin composition for a heat shrinkable film, characterized in that represented by the following formula (1):
[Formula 1]
(THI) ₂ RMQp
In Chemical Formula 1,
The two THI ligands are the same or different from each other and are tetrahydroindenyl or a derivative thereof substituted or unsubstituted by a substituent,
The substituent may be selected from the group consisting of phenyl (Ph), benzyl (Bz), naphthyl, indenyl, benzindenyl, methyl, ethyl, n- (i-Pr), n-butyl, t-butyl, trimethylsilicon group (Me ₃ Si), alkoxy, cycloalkyl and halogen Or more,
R is a structural crosslink that imparts steric stiffness between two THI ligands, and is an alkylidene group, alkylenyl group, germanium group, silicon group, siloxane group, alkylphosphine group or amine group containing 1 to 20 carbon atoms. ,
M is a transition metal of group IIIB, IVB, VB or VIB,
Q is a hydrocarbyl group or halogen having 1 to 20 carbon atoms,
p is 1 to 4;
The method of claim 1,
Melt index (ASTM D1238, 230 ℃, 2.16kg) of the metallocene linear low density polyethylene is 0.3 to 1.2 g / 10min polyethylene resin composition for heat shrink film.
The method of claim 1,
Polyethylene resin composition for heat shrink film, characterized in that the density of the metallocene linear low density polyethylene (ASTM D1505, 23 ℃) is 0.923 to 0.932 g / cc.
A heat shrink film produced from the polyethylene resin composition according to any one of claims 1 to 5.
The method according to claim 6,
The heat shrink film, characterized in that the expansion rate in the transverse direction (TD) direction less than 7% during the heat shrink process of the heat shrink film.