KR100645663B1 - Compositions for wrap film and method for preparing wrap film using the same - Google Patents

Abstract

The present invention relates to an ethylene-propylene copolymer comprising a melt index of 3.0 to 15 g / 10 minutes, 2 to 5% by weight of ethylene, or an ethylene-propylene-butene copolymer containing 2 to 5% by weight of ethylene-butene. Styrene of styrene-ethylene-butylene copolymer with 30 to 80% by weight of polypropylene resin and 1.0 to 10.0 g / 10 minutes of melt index, 0.87 to 0.92 g / cm3 and 10 to 30% by weight of styrene It relates to a composition for a PVC replacement wrap film and a method for producing a wrap film using the same, characterized in that consisting essentially of 20 to 70% by weight of the ethylene-based copolymer resin. The wrap film according to the present invention is free from the detrimental problem of environmental hormones caused by the PVC wrap film and the gloss and tackiness of the polyethylene film.

Polypropylene resin, styrene copolymer resin, wrap film, environmental hormone, glossiness, adhesiveness

Description

Wrap film composition and method for preparing wrap film using the same {Compositions for wrap film and method for preparing wrap film using the same}

The present invention relates to a composition for a PVC (polyvinyl chloride) wrap film (wrap film) and to a method for producing a wrap film using the same, in particular, polypropylene resin and styrene copolymer as an essential component gloss and adhesive It relates to a composition for a wrap film which is excellent and does not have a problem of environmental hormones, and to a wrap film produced using the same.

Wrap film is used to package boxes, bags and goods. The wrap film made of conventional PVC is an appropriate resin in terms of price and performance, and has excellent softness, adhesiveness and transparency, and is excellent in moldability. It is the most widely used material in the packaging of goods worldwide. However, the PVC wrap film has a very thin wrap film thickness, which makes it very difficult to work with a blown and straight die (T-die) manufacturing method. In addition, in order to manufacture a conventional PVC wrap film, in order to impart softness to PVC and the like, various additives such as plasticizers are prescribed at about 30% by weight, and the situation of environmental hormones is controversial.                         

Accordingly, a wrap film using a polyolefin-based resin or the like rather than PVC has been developed. However, the wrap film manufactured using polyethylene resin has no environmental hormone problem compared to the PVC wrap film, so it is applied to the home to some extent. However, the adhesive film and transparency are inferior to that of the PVC wrap film for industrial use. The situation is a bit difficult to penetrate.

U.S. Patent No. 4,425,268 describes resin compositions and molding techniques for making wrap films using polyethylene and ethylene-vinyl copolymers. According to the contents disclosed in the patent, 40 to 90% of ethylene vinyl acetate containing 4 to 25% by weight of vinyl acetate having a melt index (MI) of 0.1 to 4.0 and 8 to 25% of an ethylene copolymer having a density of 0.917 to 0.945 Mention is made of methods for making stretchable wrap films by mixing.

U. S. Patent No. 5,902, 684 describes a composition for a multilayer metallocene stretch wrap film. The core layer is composed of a propylene-ethylene random copolymer, homopolypropylene or a resin mixture thereof, the melt index of the propylene-ethylene copolymer is 2 to 15, the ethylene content is 2 to 6% by weight, the copolymer polypropylene The melt index of is said to be 2 to 15. The wrap film prepared by containing ethyl vinyl acetate may have a problem that the smell of the product due to the vinyl group may be a problem, and the film of other structures may have problems such as deterioration of adhesiveness and transparency compared to PVC. .

U. S. Patent No. 5,617, 707 discloses a method for preparing a wrap film using linear polyethylene from which a high content of normal hexane can be extracted in order to impart tack, but there is a problem such as deterioration of transparency.

Therefore, in the present invention, by using a composition consisting essentially of polypropylene resin and styrene copolymer resin, it was possible to increase the adhesiveness and transparency, to prevent the risk to environmental hormones, the present invention was completed based on this.

Accordingly, an object of the present invention is to provide a composition for polyolefin-based wrap film that increases the adhesiveness and transparency, and prevents the risk to environmental hormones.

Another object of the present invention to provide a method for producing a wrap film that can replace the PVC wrap film prepared using the composition.

Composition for the wrap film of the present invention for achieving the above object is an ethylene-propylene copolymer comprising a melt index of 3.0 to 15 g / 10 minutes, 2 to 5% by weight of ethylene, or 2 to 5% by weight of ethylene-butene 30 to 80% by weight of polypropylene-based resin of the ethylene-propylene-butene copolymer containing ethylene, and a melt index of 1.0 to 10.0 g / 10 minutes, a density of 0.87 to 0.92 g / cm 3, and 10 to 30% by weight of styrene And 20 to 70% by weight of styrene-based copolymer resin of the styrene-ethylene-butylene copolymer.

Method for producing a wrap film according to the present invention for achieving the above another object consists of molding the composition at a temperature of 180 to 250 ℃ using a straight die (T-die) film processing equipment.

Looking at the present invention in more detail as follows.

As described above, the composition according to the present invention is a polypropylene-based water as the first component.

It is essentially composed of 30 to 80% by weight and 20 to 70% by weight of the styrene-based copolymer resin as the second component.

The polypropylene-based resin has a melt index (ASTM D1238, MI, 230 ℃) of 3.0 to 15 g / 10 minutes, ethylene-propylene copolymer containing 2 to 5% by weight of ethylene, or 2 to 5% by weight of It consists of 30 to 80% by weight of ethylene-propylene-butene copolymer resin containing ethylene-butene. At this time, if the amount of resin used is less than 30% by weight, the transparency of the film is lowered, and if it exceeds 80% by weight, the adhesiveness and softness of the film tend to be lowered. In addition, when the melt index is less than 3.0 g / 10 minutes, the workability and transparency is lowered, and when the melt index exceeds 15 g / 10 minutes, mechanical properties tend to be lowered, and the content of ethylene and ethylene-butene is less than 2% by weight. The softness and transparency of the back film are lowered, and when it exceeds 5% by weight, not only the product price is increased but also raw material is not easily purchased.

The styrene-based copolymer resin as the second component has a melt index (ASTM D1238, MI, 230 ° C.) of 1.0 to 10.0 g / 10 minutes, a density of 0.87 to 0.92 g / cm 3, and a styrene content of 10 to 30% by weight. And 20 to 70% by weight of hydrogenated styrene-ethylene-butylene copolymer resin. At this time, when the amount of resin used is less than 20% by weight, the adhesiveness of the film is lowered, and when the amount of the resin is used is higher than 70% by weight, the price competitiveness of the film tends to be lowered. In addition, when the melt index is less than 1.0 g / 10 minutes, the workability and transparency are lowered, and when the melt index is greater than 10.0 g / 10 minutes, the mechanical properties tend to be lowered. When the styrene is less than 10 wt%, the transparency is excellent but the material If the price is higher than 30% by weight, the stiffness is increased, which makes it difficult to apply to the wrap film. On the other hand, the density is changed depending on the styrene content.

The first component improves and maintains the glossiness and workability of the wrap film, and the second component functions to impart soft touch softness, adhesion and restoring force.

On the other hand, if necessary to control the adhesiveness to the composition, as the third component, an adhesive such as polybutene or polyisobutylene may be added less than 3,000 ppm. The addition of the pressure-sensitive adhesive is to give an increase in the adhesion between the film and the layer to be bonded.

Processing equipment and conditions for producing a wrap film using the composition are as follows. The processing machine uses a commercially available straight die (T-die) film machine for producing single layer or multilayer polyolefin film, and the temperature of the resin extruded from the die is suitably 180 to 250 ° C. When the molding temperature is low, melt fracture occurs on the surface of the film, thereby decreasing gloss and transparency of the film. When the temperature is high, the resin may be decomposed to change the color of the film. Moreover, it is preferable to shape | mold the film thickness to 8-20 micrometers which is a normal wrap film thickness.

On the other hand, the composition can be molded by laminating at least one layer on the wrap film.

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

Example 1

As shown in the table below, the styrene-ethylene-butylene copolymer resin (denoted by S) with a MI of 4.5, a density of 0.99 and a styrene / ethylene to butylene ratio of 12/88 and a C2 content of 3.0 and MI The composition of ethylene-propylene copolymer resin (represented by R) of = 8.0 was kneaded at about 200 to 240 ° C. using a 30ψ twin screw compounder and about 20 using a film forming machine for straight dies. A wrap film was prepared in μm (die temperature = 230 ° C.).

The wrap film of the present invention was compared with conventional PVC and polyethylene wrap films for physical properties such as tensile strength, elongation, resilience, transparency, harmfulness and adhesion of environmental hormones. The stability test was carried out by any method of measuring the maximum length of the glass tube marks not remaining when pressed into a glass tube with a diameter of 10 mm after lapping to the glass.

The results are shown in Table 1 below.

division Example 1 PVC wrap Polyethylene wrap Tensile Strength (㎏ / ㎠) MD (machine direction) 493 392 435 TD (landscape) 320 248 293 Elongation (%) -MD 227 215 610 -TD 782 309 474 Resiliency (cm) 2.5 3.0 1.8 Transparency (%) 0.2 0.2 1.5 Environmental hormones × ○ × Adhesiveness (g) 3.2 4.5 1.4

As shown in Table 1, the wrap film made of a resin made of a polypropylene resin and a styrene-based copolymer showed similar results in other physical properties as compared to the conventional PVC wrap film, but there was no harmful effect of environmental hormones. It was found to be excellent in transparency and tack compared to the film.

Example 2

As shown in Table 2 below, styrene-ethylene-butylene copolymer resin (S) and C2 content = 3.0 weight as MI = 4.5, density: 0.89, styrene / ethylene and butylene ratio = 12/88 as essential components %, Ethylene-propylene copolymer resin (R) with MI = 8.0, or C2 content = 2.5 wt%, butene content = 5.0 wt%, ethylene-propylene-butene copolymer resin (T) with MI = 5.5 Then, a 20 µm film was prepared in the same manner as in Example 1 using the composition to which 3,000 ppm of polyisobutylene resin adhesive was added.

division S: R = 1: 1 S: T = 1: 1 S: T = 4: 6 S: T = 3: 7 S: T = 2: 8 Adhesiveness (g) 13.1 13.2 9.5 6.7 6.2 Tensile Strength Yield Point (㎏ / ㎠) -MD 68.6 61.0 77.5 103.8 121.2 -TD 63.1 57.1 72.0 99.2 126 Tensile Strength Breaking Point (㎏ / ㎠) -MD 550 445 501 559 516 -TD 216 441 444 353 492 Transparency (%) 0.2 0.1 0.2 0.2 0.2

As shown in Table 2, the film using the ethylene-propylene copolymer or the ethylene-propylene-butene copolymer has no significant difference in transparency and tackiness, but increases as the ratio of ethylene-propylene-butene copolymer resin increases. It can confirm that this falls

As described above, the composition made of the polypropylene resin and the styrene-based copolymer of the present invention is free from the problem of deterioration in transparency, adhesiveness, etc. of the wrap film made of polyethylene resin, and environmental hormones caused by the PVC wrap film, and post-processing. It is simple and has excellent wrap characteristics.

Claims (4)

Polypropylene-based resin of an ethylene-propylene copolymer containing a melt index of 3.0 to 15 g / 10 minutes, 2 to 5% by weight of ethylene, or an ethylene-propylene-butene copolymer containing 2 to 5% by weight of ethylene-butene Styrene-based copolymer of styrene-ethylene-butylene copolymer with styrene of 30 to 80 wt%, and melt index 1.0 to 10.0 g / 10 min, density 0.87 to 0.92 g / cm 3, 10 to 30 wt% Composition for wrap film, characterized in that consisting essentially of 20 to 70% by weight of the resin. The composition of claim 1, wherein the composition further comprises an adhesive of 3,000 ppm or less of polybutene or polyisobutylene resin. A method for producing a wrap film, characterized in that the composition according to claim 1 or 2 is molded at a temperature of 180 to 250 ° C. at a temperature of 180 to 250 ° C. using a straight die (T-die) film processing machine. The method of claim 3, wherein the composition is laminated to the wrap film in at least one layer and molded.