KR101814917B1 - Low-density polyethylene for extrusion coating a composition - Google Patents

Abstract

The present invention relates to low density polyethylene compositions for extrusion coating.
The present invention provides a low density polyethylene composition for extrusion coating which has excellent adhesion to a base material during extrusion coating, secures low-temperature sealing characteristics and maintains slipability for a long term, and is a composition comprising a polyolefin copolymer containing a low-density polyethyl group.
The present invention can be widely applied to packaging materials such as foods, medicines, confectionary, and the like because extrusion processing is operated at a low temperature and the contact force of substrates such as cellophane, slip persistence and lamination processing can be efficiently performed, There is an advantage to be able to.

Description

[0001] The present invention relates to a low-density polyethylene composition for extrusion coating,

The present invention relates to a low density polyethylene composition for extrusion coating, and more particularly to a low density polyethylene composition for extrusion coating, which comprises an anti-blocking agent, a slip agent, a blend or masterbatch with a polar polyolefin copolymer and a low density polyethylene, The present invention relates to a composition for lamination which is excellent in adhesion to substrates such as cellophane and has excellent slip persistence.

Conventionally, in the case of food packaging, low-density polyethylene is generally used as a packaging film, which is conventionally used in blown film forming, cast film forming and extrusion coating processing. In addition, In case of film molding, inorganic particles such as elasticity, silica, zeolite and the like are used for the anti-blocking property in order to secure the anti-blocking property and the slip property for the post-processing property, or polymethyl methacrylate PMMA), and polystyrene (GPPS) The slip property of the slurry was determined by using an amide slip agent.

When low density polyethylene is used for extrusion coating, polyethylene is used as a sealing layer, and polyethylene terephthalate, cellophane, aluminum or the like is coated on the inner surface to be used as a sealing layer.

The low-density polyethylene used as such a sealing layer is excellent in chemical resistance and harmless to the human body, and thus is widely used for food packaging and inner surfaces of medical packaging paper. However, because of its non-polarity, And is oxidized to oxygen in the air to be processed into a property of bonding to a substrate.

Since such a high-temperature processing is performed, there is a problem that excessive defects arise due to problems such as generation of neck, and decomposition occurs at a processing temperature when a general additive such as a slip agent is added. In the case of a general slip agent, slip behavior is lost, And the decomposition residue further weakens the adhesion between the low-density polyethylene and the substrate. In the extrusion coating method, the slip agent is used without mixing the slip agent.

In addition, in order to exhibit slipability and anti-blocking property, starch powder or the like is applied to the extrusion coating. However, since the secondary contamination is caused by the starch used, the inside of the factory is dirty, There is a problem of contamination which is caused by the residual.

Further, a method of forcibly oxidizing the low-density polyethylene melt by using ozone treatment or the like is used in order to increase the adhesive force between the deficient substrate and the sealing layer, but there is a limit to the increase of the adhesive strength, In addition, there is a problem of odor due to ozone generation and health problems of the workers in the processing step, so attention is required during use.

In order to overcome the disadvantages of such extrusion coating, extrusion coating has been attempted by using a master batch containing an anti-blocking agent and a slip agent, or by using a composition containing an anti-blocking agent and a slip agent. However, Decomposition of the additive and deterioration of the adhesive strength with the substrate occur, and it is difficult to keep the slip property continuously, and thus it is not commercially used.

· Published Korean Patent Application Publication No. 2001-112675 (Published date: December 21, 2001) · Published Japanese Patent Application No. 2003-55492 (Published Date: 2003.07.04) · Domestic Patent Registration No. 0524092 (Notice Date: Feb. 12, 2006) · Domestic patent registration system 0622429 (public announcement date: September 11, 2006) · Published Japanese Patent Application No. 2007-68697 (Published date: 2007.07.02) · Published Korean Patent Application No. 2007-104519 (Published on October 26, 2007) · Domestic patent registration system 0876512 (Notice date: December 31, 2008) · Domestic patent registration system 0882808 (Notice date: 2009.02.10)

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The present invention solves all of the drawbacks of the above-mentioned point of view based on many years of experience, and has a low density for extrusion coating having an excellent adhesion to a base material during extrusion coating and a long-lasting slip property while securing low- It is an object of the present invention to provide a polyethylene composition.

The composition of the low density polyethylene for extrusion coating is characterized by containing a low density polyethylene and a polyolefin copolymer containing an anti-blocking agent, an organic slip agent and a polar group.

More specifically, the composition ratio of the low density polyethylene composition for extrusion coating is as follows.

The content of the composition is 2 to 10% by weight of a polyolefin copolymer composition containing a polar group in 83.5 to 96.92% by weight of low density polyethylene for extrusion coating, 1 to 5% by weight of a polyolefin elastomer, 0.05 to 1% by weight of an anti- , 0.03 to 0.5 wt% of an organic slip agent.

The polar group-containing polyolefin copolymer used in the present invention is an ethylene acrylate copolymer which is obtained by copolymerizing ethylene with one or more acrylate monomers, and examples of the acrylate monomers of the copolymer include methyl acrylate, Ethyl acrylate, butyl acrylate, 2-hydroxyethyl acrylate, and the like.

The content of the acrylate component in the ethylene acrylate copolymer is preferably 10 to 30% by weight or less, and if it is less than 10% by weight, the adhesive strength may be lowered. If the acrylate content is more than 30% by weight, Thereby inhibiting the slip property.

Also, the content of the copolymer in the composition should be 2 to 10 wt%, more preferably 2 to 5 wt%. When the content is less than 2% by weight, the adhesive strength to the substrate decreases during the low-temperature processing and peeling phenomenon occurs. When the content is more than 10% by weight, the specific odor of the acrylate polymer is generated in the processed film.

In addition, a copolymer or graft composition having a polar group-containing polyolefin copolymer having an acid or anhydride exhibits excellent adhesion to a substrate and does not cause a peeling phenomenon. However, due to the strong adhesive force with metal, Gel is easily generated, and purging is difficult when the product is replaced.

The polyolefin elastomer of the present invention should have a density of 0.87 to 0.91 or less, a melt index of 0.5 to 10 or less, and a comonomer of an elastomer should be composed of butene, hexene, and octene. Particularly, when the density is less than 0.87, a problem of blocking may occur. When the density is higher than 0.91, low-temperature fusing characteristics are decreased and slipperiness is decreased.

In this composition, the polyolefin elastomer should be used in an amount of 1 to 5% by weight, and if it is less than 1% by weight, the low-temperature sealing property is hardly improved, and if it is more than 5% by weight,

The anti-blocking agent that can be used in the present invention may have an average particle size of 2 to 10 탆, a bulk density of 0.4 to 0.5 g / ml, and an average pore size of 8 Lt; RTI ID = 0.0 > to 15 < / RTI > The zeolite-based blocking agent may have a specific surface area of 80 to 200 m < 3 > so that the zeolite-based anti-blocking agent serves as an anti-blocking agent within the range not lowering the transparency of the film, And when the concentration of the slip agent on the surface which is lost in the process of storing the finished film is decreased, the slip agent concentration in the film is decreased so that the slip agent collected in the zeolite is further discharged, Can be made constant.

At this time, the concentration of zeolite can be used in the range of 0.05 wt% to 0.5 wt% with respect to the composition. If it is less than 0.05 wt%, it is difficult to maintain the anti-blocking property and the ability to collect slip agent decreases. On the other hand, when the content is more than 0.5% by weight, it is difficult to maintain the transparency of the film, and it is difficult to exhibit the characteristics of the slip agent due to excessive adsorption.

The anti-blocking agent includes a silica-based anti-blocking agent. The porous silica can be used without any particular limitation, and the average particle size is 3 to 6 μm, and the volume of pores per unit weight can be 0.5 to 0.8 ml / g. The content of SiO2 can be 99% or more.

In addition, the silica-based anti-blocking agent is contained in an amount of 0.05% by weight to 0.5% by weight based on the composition. If the amount of the silica-based anti-blocking agent is less than 0.05 wt%, sufficient blocking prevention effect can not be exhibited. If the amount exceeds 0.5 wt%, transparency of the film is decreased.

The slip agent is used for slip resistance in a polyolefin-based film, and the organic slip agent is usually a fatty acid amide, and saturated and unsaturated amides or saturated and unsaturated alkylene bisamides may be used.

Examples of amides also include, but are not limited to, palmitamide, stearylarachideamide, stearamidoethylstearamide, stearamidoethylpalmitamide, erucamide, Oleamide, erucamidoethylerucamide, stearamidoethylerucamide, and oleoamidoethylerucamide. The term " oleamide "

If the amount of the slip agent is less than 0.03% by weight, it is difficult to exhibit a desired slip property. When the amount of the slip agent exceeds 0.5% by weight, Resulting in very poor sealing characteristics and causing defects by peeling off from the substrate.

The composition for a low-density polyethylene for a film of the present invention may be applied to a film using a banbury mixer, a co-kneader, a roll mill, a uniaxial or biaxial extruder, Composition can be made. At this time, the composition molding temperature may be 180 ° C to 260 ° C, preferably 190 ° C to 240 ° C.

The present invention relates to a low-density polyethylene composition which can be extruded at a low temperature, has good adhesion to substrates such as cellophane, has excellent slip durability, can efficiently perform lamination processing and is not harmful to human body, And can be widely used in wrapping paper such as confectionery.

The detailed description of the present invention is as follows.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to these examples.

Example 1

The low density polyethylene used in the examples used was 91.5% by weight of LB5000 (ML = 5, density 0.918) manufactured by LG Corp., 5% by weight of DuPont ELVALOY AC 1820 as an ethylene acrylate copolymer, and ELVALOY AC 1820 was methyl A coating resin having an acrylate content of 20% and a melt index of 8 (190 DEG C, 2.16 kg). In the case of the polyolefin elastomer, 3 weight% of LC670 (number of fused paper 5 g / 10 min, density 0.87 g / ml) of LG Corp. was used, 0.2 weight% of Sylobloc S500 and 0.3 weight of erucamide as an anti- %, And mixed using a Henschel mixer, followed by extrusion in a twin-screw extruder to complete the composition.

The finished composition and the composition of the above-mentioned Examples and Comparative Examples were laminated to a substrate such as cellophane coated with an anchor coating agent at 280 to 300 캜 in an extrusion coater. After 72 hours, The sealability was measured using a tilt tester. The sealing temperature was 95 ° C / 98 ° C / 101 ° C / 104 ° C / 107 ° C, contacted for 2 seconds at a pressure of 2 kg / cm3, sufficiently cooled, min, the low-temperature fusing temperature, the fusing strength, and the peeling-off of the substrate were determined.

The slip property of the low-density polyethylene as the sealing layer was measured by a friction coefficient tester and is shown in Table 1.

Example 2

3% by weight of Elvalloy AC 3427 available from DuPont, which is an ethylene butyl acrylate copolymer, was added to 93.3% by weight of LB5000 of LG used in the low density polyethylene. The butyl acrylate content was 27% kg). The polyolefin elastomer was obtained by melt-kneading 2 wt% of LC670 (number of juniting paper 5 g / 10 min, density 0.87 g / mL) manufactured by LG Corp. using a kneader at 140 ° C to 180 ° C while adding Sylobloc S500 0.3 By weight and 0.4% by weight of slip zine erucamide are mixed and granulated.

This was processed and measured in the same manner as in Example 1,

Comparative Example 1

While mixing 4% by weight of the polyolefin elastomer LC670 mentioned above with 95.6% by weight of low-density polyethylene in a Henschel mixer, 0.2% by weight of Sylobloc S500 and 0.2% by weight of slurry of erucamide were added as anti-blocking agents to the twin-screw extruder To prepare a composition. The composition was processed and measured in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 2

3% by weight of Elvalloy AC 3427, which is an ethylene butyl acrylate copolymer, was added to 93.8% by weight of low density polyethylene, 3% by weight of a polyolefin elastomer LC670 was mixed with a Henschel mixer, and 0.2% by weight of slip- The composition was completed with an extruder, and processed and measured in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 3

To the 95.5% by weight of low density polyethylene, 4% by weight of ethylene methyl acrylate copolymer ELVALOY AC1820 was added and 0.2% by weight of anti-blocking agent Sylobloc S500 and 0.3% by weight of slurry of erucamide were added to the twin-screw extruder to complete the composition And processed and measured in the same manner as in Example 1. The results are shown in Table 1.

Example 1

Example 2
Comparative Example 1
Comparative Example 2
Comparative Example 3
LDPE

100
100
100
100
100
EMA

5
4
EBA

4
3
POE

3
2

4

3
A / B

0.2
0.3
0.2
0.2
Slip system

0.3
0.4
0.2
0.2
0.3
Low temperature fusion temperature

95
98
104
98
107
Peeling

Good
Good
Weak separation
Good
Good
Coefficient of friction

0.15
0.12
0.2
0.18
0.2
Fusion strength

1.5kg or more
1.5kg or more
1.5kg or more
1.5kg or more
Less than 1kg

· Low temperature fusion temperature: The minimum temperature

· Peeling or not: Judging whether or not peeling occurs between the cellophane and low density polyethylene as a base material in the fusion strength test.

· Sealing strength: The value measured by measuring the strength of the fused film at 104 ° C.

· Coefficient of friction: 0.1 ~ 0.15 Excellent, 0.15 ~ 0.24 Good, 0.24 or more poor

The slip and coefficient of friction were measured again after 4 weeks, 8 weeks and 20 weeks to measure the change with time for the Examples and Comparative Examples. The results are shown in Table 2.

Example 1

Example 2
Comparative Example 1
Comparative Example 2
Comparative Example 3



After 4 weeks


Peeling

Good
Good
Weak separation
Good
Good
Dynamic friction

0.14
0.12
0.18
0.2
0.18
Sealing strength

1.5kg or more
1.5kg or more
1kg or more
1.5kg or more
Less than 1kg



After 8 weeks

Peeling

Good
Good
Exfoliation
Good
Good
Dynamic friction

0.15
0.14
0.21
0.35
0.21
Sealing strength

1.5kg or more
1.5kg or more
1kg or more
1.5kg or more
Less than 1kg



After 20 weeks

Peeling

Good
Good
Exfoliation
Good
Good
Dynamic friction

0.2
0.18
0.21
0.5
0.25
Sealing strength

1.5kg or more
1.5kg or more
Less than 1kg
1.5kg or more
Less than 1kg

· Sealing strength: 1.5kg or more means cohesive failure.

lkg or more is a little insufficient level, lkg or less is not properly welded.

Claims (5)

To 83.92% by weight of low density polyethylene for extrusion coating,
2 to 10% by weight of a polar group-containing polyolefin copolymer composition,
1 to 5% by weight of a polyolefin elastomer,
An antiblocking agent in an amount of 0.05 to 0.7% by weight,
0.03 to 0.5% by weight of an organic slip agent,

The polar group-containing polyolefin copolymer is a polyolefin-
As the ethylene-acrylate-based copolymer, it is preferable that the content of the acrylate component is 10 to 30% by weight in the ethylene copolymer with one or more acrylate monomers,

The polyolefin elastomer may include,
A density of 0.87 to 0.91 g / ml, a melt index of 0.5 to 20 g / 10 min,

Wherein the organic slip agent comprises:
Fatty acid amide, a saturated or unsaturated amide or a saturated and unsaturated alkylene bisamide, is used as the low-density polyethylene composition for extrusion coating delete delete delete delete