KR101831530B1 - Resin composition of polyethylene for extrusion coating and lamination coating and the molded article by using the same - Google Patents

Abstract

Disclosed are a polyethylene resin composition for extrusion lamination coating which is applicable to a packing material and a paper container by having excellent heat resistance and adhesive strength and having an excellent balance of draw down properties and neck-in properties, and a molded article manufactured by using the polyethylene resin composition. The polyethylene resin composition of the present invention comprises: 70 to 90 wt% of a low density polyethylene polymer (A) having a melt index (190°C, 2.16 kg) of 5 to 10 g/10 min and a density of 0.915 to 0.924 g/cm^3; and 10 to 30 wt% of a high density polyethylene polymer (B) having a melt index (190°C, 2.16 kg) of 10 to 30 g/10 min and a density of 0.950 to 0.970 g/cm^3, wherein the low density polyethylene polymer is formed by primarily polymerizing raw materials in an autoclave reactor to obtain a primarily polymerized material and continuously injecting the primarily polymerized material into a tubular reactor, thereby additionally polymerizing the primarily polymerized material in the tubular reactor.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene resin composition for extrusion lamination coating and a molded article using the same.

More particularly, the present invention relates to a polyethylene resin composition for extrusion lamination coating excellent in heat resistance, adhesive strength and molding balance, and a molded article produced using the same. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene resin composition for extrusion lamination coating and a molded article produced using the same. will be.

The purpose of extrusion coating and lamination is to prepare new high-performance composite materials by integrating the coating resin and the substrate to be coated so as to complement each other.

Composite materials produced by extrusion coating and extrusion lamination are mainly used as packaging materials, paper containers, etc., and various resins and additives are used in order to impart characteristics suitable for their use. In case of release paper, paper cup, noodle container, etc., there is a possibility of exposure to high temperature when using finished products and finished products. If the heat resistance of coating resin is low, the coating resin may be softened or adhesive strength may be lowered do.

In recent years, extrusion coating and lamination processing are required to have high properties at the high speed of lamination molding machines. However, when the polyethylene composition for extrusion coating lamination used at the present time is molded at high speed, necking is increased and molding defects such as surging and drop- Lt; / RTI > In order to improve the high-speed processability, the content of the linear low-density polyethylene or the high-density polyethylene is increased. However, as the content of the linear low-density polyethylene or the high-density polyethylene is increased, the extrusion load is increased. Occurs.

Korean Patent No. 1180634 discloses a polyethylene resin composition having a low water permeability through an increase in the content of high-density polyethylene. However, there is a problem in that the adhesive strength and the toughness of the composition are deteriorated during the coating molding.

Korean Patent No. 0715612 discloses a polyethylene resin composition containing a high-density polyethylene resin and having excellent draw-down and neck tough balance control and excellent pinhole property and curl. However, when a resin having the composition is used, the adhesive strength and the neck toughness There is a problem.

Korean Patent No. 1237228 discloses a resin composition containing low-density polyethylene, linear low-density polyethylene and magnesium stearate, but has a low softening point of linear low-density polyethylene and thus has a problem in heat resistance.

Japanese Patent No. 2978387 discloses a resin composition for lamination which is improved in processability by addition of linear low density polyethylene and is excellent in low temperature heat sealability, heat bonding strength and hot tackiness. However, since the softening point of linear low density polyethylene is low, have.

DISCLOSURE OF THE INVENTION Accordingly, the present invention has been made to solve the above problems, and it is an object of the present invention to provide a polyethylene resin composition for extrusion lamination coating which is excellent in heat resistance and adhesive strength and excellent in balance of drawdown property and neck toughness, And to provide the molded article thus produced.

(A) 70 to 90% by weight of a low density polyethylene polymer having a melt index (190 占 폚, 2.16 kg) of 5 to 10 g / 10 min and a density of 0.915 to 0.924 g / cm3; And 10 to 30% by weight of a high density polyethylene polymer having a melt index (190 占 폚, 2.16 kg) of 10 to 30 g / 10 min and a density of 0.950 to 0.970 g / cm3, wherein the low density polyethylene polymer is an autoclave Polymerized into a reactor, continuously fed into a tubular reactor, and further polymerized to provide a polyethylene resin composition for extrusion lamination coating.

And the low-density polyethylene polymer has a Z-average molecular weight of 400,000 to 700,000. The present invention also provides a polyethylene resin composition for extrusion lamination coating.

And the low density polyethylene polymer has a molecular weight distribution (Mw / Mn) of 8 to 13. The present invention also provides a polyethylene resin composition for extrusion lamination coating.

Also, there is provided a polyethylene resin composition for extrusion lamination coating characterized by having a neck toughness of 50 mm or less and a draw-down property of 150 m / min or more as measured by the following method at the time of extrusion coating according to the following method using the polyethylene resin composition .

[Extrusion coating molding method]

The polyethylene resin composition was coated on the biaxially stretched polypropylene film at a die temperature of 310 占 폚 using a die 450 mm uniaxial extrusion laminator.

[Measuring method of neck toughness]

The difference between the die width and the width of the coating film when the coating thickness is 20 μm is measured in an extrusion laminator under the conditions of a screw speed of 35 rpm and a coating line speed of 60 m / min.

[Measuring method of drawdown property]

The maximum line speed at 35 rpm of the screw of the extrusion laminator was measured.

The polyethylene resin composition for extrusion lamination coating is characterized in that the molded article molded by the extrusion coating has a heat bonding temperature of 110 캜 or less and a heat resistance of 95 캜 or more, measured according to the following method.

[Measurement method of heat bonding temperature]

The polyethylene resin composition was coated on a biaxially stretched polypropylene film using an extrusion laminator at a die temperature of 310 DEG C, and then the two film specimens were heat-sealed at 2 kgf / cm < 2 > for 1 second using a heat seal temperature meter. Measures temperatures in excess of 1,000 gf.

In order to solve the above-described problems, the present invention provides a molded article which is extrusion-laminated using the resin composition.

According to the present invention, it is possible to provide a resin composition excellent in balance of high-speed processability (draw-down property) and neck toughness and excellent in heat resistance by containing an optimal content of a low density polyethylene polymer and a high density polyethylene polymer continuously polymerized by an autoclave reactor and a tubular reactor .

Also, by using extrusion coating, lamination coating molding or the like, it is possible to produce a plastic coating product having excellent adhesive strength and excellent heat resistance.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. It is to be understood that various equivalents and modifications may be substituted for those at the time of the present application.

(A) 70 to 90% by weight of a low density polyethylene polymer having a melt index (190 占 폚, 2.16 kg) of 5 to 10 g / 10 min and a density of 0.915 to 0.924 g / cm3; And 10 to 30% by weight of a high density polyethylene polymer having a melt index (190 占 폚, 2.16 kg) of 10 to 30 g / 10 min and a density of 0.950 to 0.970 g / cm3, wherein the low density polyethylene polymer is an autoclave Polymerized into a reactor, continuously fed into a tubular reactor, and then further polymerized, thereby producing a polyethylene resin composition for extrusion lamination coating.

Hereinafter, each constitution of the polyethylene resin composition for extrusion lamination coating according to the present invention will be described in detail.

(A) a low density polyethylene polymer

In the present invention, the low density polyethylene polymer is characterized by continuous polymerization with an autoclave reactor and a tubular reactor.

The use of the low density polyethylene polymer produced by using the autoclave reactor and the tubular reactor simultaneously in the present invention is effective in balancing the high coatability (drawdown property) and the neck toughness and improving the yield, It is expected that the molding balance can be remarkably improved, particularly when compared with the case of using the low-density polyethylene polymer.

As the low-density polyethylene polymer obtained through such secondary polymerization, a low-density polyethylene polymer having a melt index of 5 to 10 g / 10 min, preferably 6 to 8 g / min, can be used. If the melt index is less than 5 g / 10 min, the draw-down property of the resin composition for extrusion coating is deteriorated, and if it exceeds 10 g / 10 min, the neck toughness of the resin composition for extrusion coating is lowered.

The density of the low density polyethylene polymer may be 0.915 to 0924 g / cm3, preferably 0.917 to 0.922 g / cm3. If the density is less than 0.910 g / cm 3, the long chain branch of the low density polyethylene is increased and the drawdown property is lowered. If the density is more than 0.924 g / cm 3, the long chain branch of the low density polyethylene is decreased and the neck toughness is lowered.

On the other hand, low density polyethylene polymers can be characterized by molecular weight and molecular weight distribution. Molecular weight distribution is a measure of the molecular weight range within a given polymer sample. The width of the molecular weight distribution can be characterized by a ratio of various molecular weight averages, for example, a ratio (Mw / Mn) of the weight average molecular weight to a number average molecular weight or a ratio (Mz / Mn) of the Z- . The average molecular weight M can be calculated from the following equation (1).

[Equation 1]

In Equation (1), N _i is the number of molecules having a molecular weight M _i . When n is 0, M is a number average molecular weight (Mn), M is a weight average molecular weight (Mw) when n is 1, and M is a Z-average molecular weight (Mz) when n is 2. The desired MWD function is the ratio of the corresponding M values. M and MWD are well known in the art and are described, for example, in Slade, PEEd., Polymer Molecular Weights Part II, Marcel Dekker, Inc., NY, (1975) 287-368; Rodriquez, F , Principles of Polymer Systems 3rd ed., Hemisphere Pub. Cor., NY, (1989) 155-160).

In the present invention, the low density polyethylene polymer preferably has a molecular weight distribution (Mw / Mn) of 8 to 13, more preferably 9 to 11. If the molecular weight distribution is less than 8, the neck toughness of the resin composition for extrusion coating may be lowered, and if it exceeds 13, the drawdown of the resin composition for extrusion coating may be lowered.

In the present invention, the low-density polyethylene polymer preferably has a Z-average molecular weight of 400,000 to 700,000, more preferably 500,000 to 600,000. If the Z-average molecular weight is less than 400,000, the long chain branch may be too small to reduce the neck toughness. If the Z-average molecular weight is more than 700,000, the long chain branch may be too large to reduce the drawdown speed.

The low density polyethylene polymer is preferably subjected to first polymerization with an autoclave reactor in which the reactor pressure is 1,500 to 1,600 kgf / cm 2, the reactor top temperature is 220 to 240 ° C and the reactor bottom temperature is 265 to 275 ° C, And then put into a secondary tubular reactor to further polymerize the low density polyethylene polymer. At this time, in the autoclave reactor, t-butyl peroxybenzoate as a polymerization initiator and di-t-butyl peroxide as a polymerization initiator are placed in the upper part of the reactor, Respectively.

If the pressure of the autoclave reactor is less than 1,500 kgf / cm 2, the long-chain branch of the low-density polyethylene becomes too large to increase the Z-average molecular weight. If the reactor pressure exceeds 1,600 kgf / cm 2, It may be difficult to obtain a desired coating property because the average molecular weight is small. If the temperature of the upper portion of the reactor is less than 220 ° C, the long chain branch of the low-density polyethylene may be reduced to increase the neck of the resin composition for extrusion coating. If the temperature of the upper portion of the reactor exceeds 240 ° C, The draw-down property of the composition may be lowered. If the temperature is lower than 265 ° C, the yield of the low-density polyethylene polymer may be lowered. If the temperature is higher than 275 ° C, the risk of explosion of the reactor is increased.

(B) High density polyethylene polymer

The high density polyethylene which is another component of the resin composition of the present invention can be produced by copolymerizing ethylene with an alpha olefin such as propylene, butene-1, hexene-1, octene-1 or the like using a Ziegler-Natta catalyst And preferably those produced by copolymerization of ethylene with propylene, butene-1 or hexene-1 can be used. The polymerization method is not particularly limited, and can be produced by any method such as a solution method or a slurry method.

In the present invention, the high-density polyethylene may have a melt index of 10 to 30 g / 10 min, preferably 15 to 25 g / 10 min. When the melt index of the high-density polyethylene is less than 10 g / 10 min, the formation of high-strength properties is deteriorated. When the melt index exceeds 30 g / 10 min, the neck toughness is lowered during the coating molding. It is not preferable because defects occur.

The density of the high-density polyethylene may be 0.950 to 0.970 g / cm3, preferably 0.955 to 0.965 g / cm3. When the density of the high-density polyethylene is less than 0.950 g / cm 3, the heat resistance is deteriorated.

The content of the high density polyethylene in the polyethylene resin composition of the present invention is 10 to 30% by weight, preferably 10 to 20% by weight based on the total amount of the low density polyethylene and the high density polyethylene. When the content of the high-density polyethylene is less than 10% by weight, the heat resistance is deteriorated. When the content of the high-density polyethylene is more than 30% by weight,

The polyethylene resin composition for extrusion lamination coating according to the present invention can be produced by a conventional polymer blending method using the (A) low-density polyethylene polymer and the (B) high-density polyethylene polymer having the above specific properties and content. For example, dry blending using a tumbler mixer or a Henschel mixer, and the dry mixed mixture may be subjected to additional melt mixing using a kneader such as an extruder, a mixing roll, a kneader, a roll mill, a Banbury mixer, have. At this time, it is preferable that the temperature during the melt-mixing of the polyethylene resin composition is maintained at 150 to 230 캜.

The polyethylene resin composition for extrusion lamination coating according to the present invention may contain various additives such as antioxidants, antistatic agents, slip agents, antiblocking agents, lubricants, pigments, dyes, plasticizers, aging agents An inhibitor, a hydrochloric acid absorbent, and the like. The amount of these additives to be used can be adjusted to the optimum range in consideration of the total production amount and the manufacturing process within the range known to be usable for manufacturing the polyethylene resin composition for extrusion lamination coating according to the present invention . The additives may be added in the step of mixing the (A) low density polyethylene polymer and (B) the high density polyethylene polymer, or may be added by kneading in a separate additional step.

The polyethylene resin composition according to the present invention can achieve remarkably improved forming balance in extrusion lamination coating. Specifically, when the extrusion coating according to the method described later is used, the measured value of the neck toughness is 50 mm or less, The durability can be more than 150 m / min.

Further, the molded product molded by the extrusion lamination coating using the polyethylene resin composition according to the present invention can realize excellent adhesive strength and heat resistance, and more specifically, the heat bonding temperature measured according to the method described below is 110 ° C or less, the heat resistance is 95 Lt; / RTI >

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. First, the physical properties of the low-density polyethylene and the high-density polyethylene used in Examples and Comparative Examples are shown in Tables 1 and 2. Measurement and evaluation of various physical properties were carried out by the following methods.

[Measurement and evaluation of physical properties]

1) Melt index: Measured by the ASTM D1238 method.

2) Density: Measured by ASTM D1505 method.

3) Molecular weight: measured by ASTM D3536 method.

4) Extrusion coating molding: The biaxially stretched polypropylene film was coated at a die temperature of 310 DEG C using a polyethylene resin composition according to the example of the present invention and a comparative example, using a die width 450 mm uniaxial extrusion laminator.

5) Neck Toughness: The die width and the width of the coating film were measured when the coating thickness of 20 탆 was formed at a screw speed of 35 rpm and a coating line speed of 60 m / min in an extrusion laminator.

6) Drawdown property: The maximum line speed at 35 rpm of the screw of the extrusion laminator was measured.

7) Thermal Adhesion Temperature: The polyethylene resin composition according to Examples and Comparative Examples of the present invention was coated on a biaxially stretched polypropylene film using an extrusion laminator at a die temperature of 310 DEG C, and then the two film specimens Was heat-sealed at 2 kgf / cm < 2 > for 1 second, and then the temperature at which the peel strength exceeded 1,000 gf was measured.

8) Vicat Softening Temperature: Measured by ASTM D1525 method.

Example  One

85% by weight of low density polyethylene (A2) and 15% by weight of high density polyethylene (B3) were mixed with a tumble mixer for 5 minutes and extruded and cooled at a temperature of 150 to 200 DEG C by a 40 mm extruder to obtain a composition in the form of a pellet, And the results are shown in Table 3 below.

Comparative Example  One

50% by weight of low density polyethylene (A2) and 50% by weight of high density polyethylene (B3) were mixed with a tumble mixer for 5 minutes, extruded and cooled at a temperature of 150 to 200 DEG C by a 40 mm extruder to obtain a pelletized composition, And the results are shown in Table 3 below.

Comparative Example  2

The composition of 100% by weight of low density polyethylene (A2) was subjected to extrusion lamination molding and physical properties were measured. The results are shown in Table 3 below.

Comparative Example  3

85 wt% of low density polyethylene (A1) and 15 wt% of high density polyethylene (B3) were mixed with a tumble mixer for 5 minutes, extruded and cooled at a temperature of 150 to 200 DEG C by a 40 mm extruder to obtain a pelletized composition, And the results are shown in Table 3 below.

Comparative Example  4

85 wt% of low density polyethylene (A3) and 15 wt% of high density polyethylene (B3) were mixed with a tumble mixer for 5 minutes, extruded and cooled at a temperature of 150 to 200 DEG C by a 40 mm extruder to obtain a pelletized composition, And the results are shown in Table 3 below.

Comparative Example  5

85% by weight of low density polyethylene (A2) and 15% by weight of high density polyethylene (B1) were mixed with a tumble mixer for 5 minutes, extruded and cooled at a temperature of 150 to 200 DEG C by a 40 mm extruder to obtain a pelletized composition, And the results are shown in Table 3 below.

Comparative Example  6

85% by weight of low density polyethylene (A2) and 15% by weight of high density polyethylene (B2) were mixed by a tumble mixer for 5 minutes and extruded and cooled at a temperature of 150 to 200 DEG C by a 40 mm extruder to obtain a composition in the form of a pellet, And the results are shown in Table 3 below.

Comparative Example  7

85% by weight of low density polyethylene (A4) and 15% by weight of high density polyethylene (B3) were mixed with a tumble mixer for 5 minutes, extruded and cooled at a temperature of 150 to 200 DEG C by a 40 mm extruder to obtain a pelletized composition, And the results are shown in Table 3 below.

Comparative Example  8

85% by weight of low density polyethylene (A5) and 15% by weight of high density polyethylene (B3) were mixed with a tumble mixer for 5 minutes and extruded and cooled at a temperature of 150 to 200 DEG C by a 40 mm extruder to obtain a pelletized composition, And the results are shown in Table 3 below.

Referring to Table 3, the coating properties of a composition prepared by incorporating an appropriate amount of a low density polyethylene polymer (B3) high density polyethylene polymer continuously polymerized in an autoclave reactor (A3) and a tubular reactor having desirable physical properties according to the present invention and It can be confirmed that the heat resistance of the coating material is excellent in comparison with the case of coating performance (Example 1), the case where it is produced using only low density polyethylene (Comparative Example 2), and the coating has excellent balance of neck toughness and drawdown property.

On the other hand, the resin composition using an excessive amount of high-density polyethylene (Comparative Example 1) is excellent in heat resistance, but has a too high heat bonding temperature, so that there is a high possibility of adhesion failure at the time of post-processing and the neck toughness is low.

In addition, in the case of the resin composition (Comparative Example 3) using low-density polyethylene having a low melt index, the drawdown property is lowered due to the low melt index despite the low Z-average molecular weight of the low-density polyethylene.

In the case of Comparative Example 4, the low-density polyethylene having a high melt index and a low density as compared with Example 1 is used, whereby the drawdown property is reduced due to the high Z-average molecular weight of the low-density polyethylene, and the melt index And there is a limit to coating molding.

In addition, in the case of the resin composition (Comparative Example 5) using a high-density polyethylene having a low melt index, the drawdown property is lowered, and the resin composition using the high-density polyethylene having a low density (Comparative Example 6) has a low heat resistance.

On the other hand, in the case of the composition (Comparative Example 7) using the low-density polyethylene produced by the autoclave alone and the low-density polyethylene produced by the tubular reactor alone having the lower limit of the heat resistance and draw- The Z-average molecular weight is low, and the neck toughness is lowered, which limits the coating molding.

While the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, Such modifications and changes are to be considered as falling within the scope of the following claims.

Claims (6)

(A) 70 to 90% by weight of a low-density polyethylene polymer having a melt index (190 占 폚, 2.16 kg) of 5 to 10 g / 10 min and a density of 0.915 to 0.924 g / cm3; And
(B) 10 to 30% by weight of a high-density polyethylene polymer having a melt index (190 占 폚, 2.16 kg) of 10 to 30 g / 10 min and a density of 0.950 to 0.970 g / cm3;
, ≪ / RTI &
Wherein the low density polyethylene polymer is polymerized in an autoclave reactor and continuously fed into a tubular reactor to further polymerize the polyethylene resin composition for extrusion lamination coating,
The polyethylene resin composition for extrusion lamination coating according to claim 1, wherein the polyethylene resin composition has a heat bonding temperature of 110 ° C or less and a heat resistance of 95 ° C or more,
[Extrusion coating molding method]
The polyethylene resin composition was coated on the biaxially stretched polypropylene film at a die temperature of 310 占 폚 using a die 450 mm uniaxial extrusion laminator.
[Measurement method of heat bonding temperature]
The polyethylene resin composition was coated on a biaxially stretched polypropylene film using an extrusion laminator at a die temperature of 310 DEG C, and then the two film specimens were heat-sealed at 2 kgf / cm < 2 > for 1 second using a heat seal temperature meter, Measures temperatures in excess of 1,000 gf. The method according to claim 1,
Wherein the low-density polyethylene polymer has a Z-average molecular weight of 400,000 to 700,000. The method according to claim 1,
Wherein the low-density polyethylene polymer has a molecular weight distribution (Mw / Mn) of 8 to 13. The polyethylene resin composition for extrusion lamination coating according to claim 1, The method according to claim 1,
Wherein the molded article molded by the extrusion coating molding method has a neck toughness of 50 mm or less and a drawdown resistance of 150 m / min or more as measured by the following method.
[Measuring method of neck toughness]
The difference between the die width and the width of the coating film when the coating thickness is 20 μm is measured in an extrusion laminator under the conditions of a screw speed of 35 rpm and a coating line speed of 60 m / min.
[Measuring method of drawdown property]
The maximum line speed at 35 rpm of the screw of the extrusion laminator was measured. delete A molded article extruded and laminated using the resin composition of any one of claims 1 to 4.