KR101738723B1 - Low temperature heat-sealing properties of atactic-polypropylene resin composition - Google Patents

Abstract

Disclosed is a polypropylene resin composition excellent in transparency and processability due to low temperature thermal adhesiveness and low film solubility, small change in printability and wettability with time, excellent kneadability and processability. (A) 78 to 98% by weight of a propylene-ethylene random copolymer containing 0.5 to 10% by weight of ethylene; (b) 0.5 to 10% by weight of polyethylene polymerized using a metallocene catalyst; (c) 0.5 to 10% by weight of polybutene-1; And (d) 1 to 15% by weight of a propylene-ethylene copolymer or an adhesive polypropylene polymerized using a metallocene catalyst.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an adhesive polypropylene resin composition having excellent heat-

The present invention relates to a polypropylene resin composition, and more particularly to an adhesive polypropylene resin composition excellent in low temperature heat sealing property.

The unleaded polypropylene film is widely used in food packaging because of its low cost and excellent thermal adhesiveness. In order to increase the production speed in packaging of such an unleaded polypropylene film, the time required for thermal bonding must be reduced. Therefore, it is necessary to adhere at a high temperature or lower the heat bonding temperature of the resin used in the heat bonding layer, and it is preferable to use a resin having a low heat bonding temperature because adhesion at a high temperature may damage the film by heat.

Polypropylene Homopolymer and Polypropylene Random Copolymer have been mainly used as a material of conventional heat-sealing synthetic film. In recent years, it has been known that ethylene-propylene-1-butene terpolymer Many studies have been made on copolymers. However, the ethylene-propylene-1-butene terpolymer still does not satisfy the low-temperature heat-sealing synthesis, and improvement thereof is required.

Generally, the thermal bonding temperature of the resin is related to the melting temperature of the resin, and the lower the melting temperature, the lower the thermal bonding temperature. As the content of ethylene and 1-butene in the ethylene-propylene-1-butene terpolymer increases, the melting temperature and the heat bonding temperature become lower. However, when the content of ethylene and 1-butene is increased in the polymerization process, a low polymer There is a problem that transparency is deteriorated and blocking is caused.

Another method for improving the heat-seal composition of a film is blending polybutene-1 or a linear polyethylene having a low heat sealing temperature with a propylene-ethylene-1-butene terpolymer .

However, when the propylene-ethylene-1-butene terpolymer and polybutene-1 are mixed, the low-temperature heat-sealability is improved, but the kneadability is poor and the fineness is limited. On the other hand, when the propylene-ethylene-1-butene terpolymer is mixed with linear polyethylene, the copolymer has excellent kneadability and transparency, but when the content of linear polyethylene is 10% by weight or more, compatibility of polypropylene with polyethylene is limited There is a drawback that the workability of the film deteriorates. In addition, since the above methods are a method of mixing two kinds of resins already produced, there is a disadvantage that the cost of the product increases.

Disclosure of the Invention The present invention has been conceived to solve the above problems and provides a polypropylene resin composition excellent in transparency and processability due to low temperature thermal adhesiveness and low melting point and little change in printing property and wettability with time, I want to.

(A) 78 to 98% by weight of a propylene-ethylene random copolymer containing 0.5 to 10% by weight of ethylene; (b) 0.5 to 10% by weight of polyethylene polymerized using a metallocene catalyst; (c) 0.5 to 10% by weight of polybutene-1; And (d) 1 to 15% by weight of a propylene-ethylene copolymer or an adhesive polypropylene polymerized using a metallocene catalyst.

According to the polypropylene resin composition of the present invention, the propylene-ethylene random copolymer, the polyethylene polymerized using the metallocene catalyst, the propylene-ethylene copolymer polymerized using the polybutene-1 and the metallocene catalyst, By combining the polypropylene with the optimal amount, it can be used for forming a film having a lower heat bonding temperature than the conventional heat bonding film. By lowering the heat bonding temperature, the energy consumption at the time of heat bonding can be reduced, It is possible to provide a polypropylene resin composition which can increase the uniformity of a product to produce a resin product excellent in kneadability and processability with less soluble components.

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 The present invention should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention. Accordingly, it is to be understood that the constituent features of the embodiments described herein are merely the most preferred embodiments of the present invention, and are not intended to represent all of the inventive concepts of the present invention, so that various equivalents, And the like.

(A) 78 to 98% by weight of a propylene-ethylene random copolymer containing 0.5 to 10% by weight of ethylene; (b) 0.5 to 10% by weight of polyethylene polymerized using a metallocene catalyst; (c) 0.5 to 10% by weight of polybutene-1; And (d) 1-15% by weight of a propylene-ethylene copolymer or an adhesive polypropylene polymerized using a metallocene catalyst. Hereinafter, each component constituting the present invention will be described in detail.

(a) a propylene-ethylene random copolymer

In the present invention, the propylene-ethylene random copolymer contains 0.5 to 10% by weight of ethylene. If the ethylene content is less than 0.5% by weight, the melting temperature of the propylene-ethylene random copolymer may be excessively increased to make it difficult to adhere thermally. When the ethylene content exceeds 10% by weight, the melting temperature of the propylene- Which may be disadvantageous for film molding.

The propylene-ethylene random copolymer preferably contains two or more propylene-ethylene random copolymers having different ethylene contents. For example, a propylene-ethylene random copolymer containing 0.5 to 2% by weight of ethylene and a propylene-ethylene random copolymer containing 2 to 8% by weight of ethylene may be mixed.

The two or more propylene-ethylene random copolymers differing in the ethylene content may be composed of a mixture of polypropylene homopolymers.

In the present invention, the propylene-ethylene random copolymer may be in the form of a powder having an average particle diameter of 5 mm or less, preferably 2 mm or less. The propylene-ethylene random copolymer preferably has a melt index (at 190 占 폚 under a load of 2.16 kg) of 1 to 15 g / 10 min and a soluble content of 2 to 8% by weight.

In the present invention, the propylene-ethylene random copolymer is contained in an amount of 78 to 98% by weight, preferably 80 to 96% by weight, and more preferably 86 to 92% by weight in the total polypropylene resin composition . If the content of the propylene-ethylene random copolymer is less than 78% by weight, the mechanical properties such as stiffness and impact strength may be changed or lowered in a product using the resin composition, and when it exceeds 98% by weight, It can be difficult to lower.

(b) Polyethylene polymerized using a metallocene catalyst

In the present invention, the polyethylene polymerized using the metallocene catalyst is preferably high-density polyethylene. The polyethylene has a role of imparting rigidity to a film using the polypropylene resin composition to prevent the occurrence of wrinkles during film winding, and to improve anti-blocking property and low-temperature thermal bonding strength.

Preferably, the polyethylene polymerized using the metallocene catalyst has a density of 0.930 to 0.950 g / ml, a powdery average of 5 mm or less, preferably 2.5 mm or less, a melt index (190 ° C, 2.16 Kg load) of 1 to 30 g / 10 min may be used.

The metallocene catalyst is not particularly limited, and a conventionally known catalyst may be used. Examples of the metallocene catalyst include titanocene, vanadocene, nickelocene, tantalocene, hafnocene, zirconocene, and molybdenocene. The polyethylene polymerized using the metallocene catalyst has a narrower molecular weight distribution than that polymerized by the conventional Ziegler-Natta catalyst, so that the blocking due to the adhesion of the low molecular weight polymer is less and the low temperature thermal adhesiveness can be improved.

In the present invention, the polyethylene polymerized using the metallocene catalyst is contained in the total polypropylene resin composition in an amount of 0.5 to 10 wt%, preferably 1 to 5 wt%, more preferably 2 to 4 wt% . If the content of polyethylene is less than 0.5% by weight, a roll mark may be generated in a product using the polypropylene resin composition. If the content exceeds 10% by weight, phase separation of polyethylene may occur and transparency may be deteriorated.

(c) Polybutene-1

In the present invention, polybutene-1 is a semicrystalline resin having a tetragonal helix or twin hexagonal helix structure and having a crystallinity of about 50% and has a melt index (190 DEG C, load of 2.16 kg) Of 0.4 to 5 g / 10 min, a melting temperature of 90 to 130 ° C, and a density of 0.890 to 0.920 g / ml.

The polybutene-1 is contained in an amount of 0.5 to 10% by weight, preferably 1 to 5% by weight, and more preferably 2 to 4% by weight in the entire polypropylene resin composition. If the content of polybutene-1 is less than 0.5% by weight, the low-temperature bonding strength of the product using the polypropylene resin composition may deteriorate. If the content of polybutene-1 exceeds 10% by weight, stickiness of the product may increase, .

(d) a propylene-ethylene copolymer or an adhesive polypropylene polymerized using a metallocene catalyst

In the present invention, the propylene-ethylene copolymer or the adhesive polypropylene polymerized using the metallocene catalyst may be a random copolymer of 2 to 20 carbon atoms, preferably 2 to 10, and may have a melt index (190 DEG C, 2.16 Kg load) of 0.1 to 30 g / 10 min, preferably 1 to 20 g / 10 min.

In the present invention, the above-mentioned conductive polypropylene is not a by-product generated in the production of polypropylene, and is a material capable of controlling the molecular weight of a polymerization base which can be polymerized in a high molecular weight, unlike the conventional adhesive polypropylene.

In addition, the above-mentioned adhesive polypropylene is an amorphous polypropylene having a low crystallinity, which is different from conventional polypropylene, and is added for the purpose of improving impact resistance, hardness and formability. In place of some or all of commonly used rubbers It is an ingredient to be blended. In addition, since the crystallinity is significantly lower than that of the conventional isotactic, it has flexibility and low shrinkage characteristics due to a reduced diameter, and it is possible to improve kneadability and workability.

In the present invention, the above-mentioned contact polypropylene includes, for example, a propylene homopolymer or a propylene-ethylene binary copolymer having a ethylene content of 1 to 20% by weight, preferably 2 to 10% by weight, Can be used.

The metallocene catalyst is not particularly limited, and a conventionally known catalyst may be used. Examples of the metallocene catalyst include titanocene, vanadocene, nickelocene, tantalocene, hafnocene, zirconocene, and molybdenocene. The polyethylene polymerized using the metallocene catalyst has a narrower molecular weight distribution than that polymerized by the conventional Ziegler-Natta catalyst, so that the blocking due to the adhesion of the low molecular weight polymer is less and the low temperature thermal adhesiveness can be improved.

In the present invention, the propylene-ethylene copolymer or the adhesive polypropylene polymerized using the metallocene catalyst is contained in an amount of 1 to 15% by weight, preferably 2 to 10% by weight, More preferably 4 to 6% by weight. If the content of the propylene-ethylene copolymer or the adhesive polypropylene is less than 1% by weight, the desired effect may not be exhibited in the product using the polypropylene resin composition. If the content is more than 15% by weight, The heat sealing strength, the optical properties and the mechanical properties may be deteriorated.

The polypropylene resin composition according to the present invention may further contain other additives in addition to the above-mentioned main components, within the range not deviating from the intended uses and effects. For example, the antistatic agent may be added in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the polypropylene resin composition of the present invention.

Here, the anti-blocking agent can minimize the migration of the soluble fraction since the anti-blocking agent serves to trap the low molecular substance so that the low molecular substance does not appear on the surface of the film. The anti-blocking agent may be silica or zeolite. At this time, silica and zeolite can be used alone, but they are preferably used together because their pore sizes are different from each other.

As the porous white amorphous silica, it is preferable that the silica has a particle size of 4.5 to 5.3 탆, a pore volume of 0.6 to 0.8 ml / g, a SiO ₂ content of 99% or less, Or more. In addition, it is preferable to use silica having a water content of less than 2% by weight at the time of drying at 160 캜.

The zeolite is not particularly limited and conventional zeolite may be used. For example, monoclinic zeolite may be used. Since the size of the zeolite particles should be applied within a range that does not lower the degree of fogging of the film, the size of the zeolite synthesized using sodalite is preferably 2 to 5 탆. The bulk density of the particles is 0.4 to 0.5 g / ml, the average pore interconnected channel is 5 to 15 angstroms, preferably 7 to 12 angstroms, and the specific surface area is 80 to 200 angstroms. M3 / g, a pH of 8 to 9, and a whiteness value of 95 or more, may be used as the porous zeolite.

The anti-blocking agent may be contained in an amount of 0.01 to 1 part by weight based on 100 parts by weight of the total polypropylene resin composition. When the content is less than 0.01 part by weight, the printing property and blocking property of a product using the polypropylene resin composition may be deteriorated If it exceeds 1 part by weight, transparency of the product may be lowered.

The antioxidant is used for preventing the resin molecules from being broken by heat, oxygen, or the like when the film is produced by using the polypropylene resin composition. The neutralizing agent is generated by the residue (metal component) of the catalyst used in the polymerization To neutralize the acid (e.g., HCl) that may be present. The ultraviolet stabilizer is for preventing the molecular chains of the resin from being broken by ultraviolet rays. The antistatic agent is for reducing the generation of static electricity in a film produced by using the polypropylene resin composition.

The production of the polypropylene resin composition of the present invention is not particularly limited and can be carried out according to a conventional method. For example, each component constituting the polypropylene resin composition of the present invention is put into a Henschel mixer in the required amount and mixed for 1 to 2 minutes under the condition of 1,000 to 1,500 rpm. The mixture is extruded at an extruder molding temperature of 160 to 210 DEG C, A 40 mm single screw extruder having L / D 35 under the processing conditions of 100 rpm.

Further, the produced resin composition can be produced by using a 40 mm uniaxially extruded film molding machine of L / D 35 under the processing conditions of an extruder molding temperature of 160 to 210 DEG C and an extruder molding speed of 100 rpm.

Hereinafter, the present invention will be described in detail with reference to examples.

Example  One

(a) 89 parts by weight of a propylene-ethylene random copolymer (ethylene content: 2 wt%, melt index: 8 g / 10 min, solubles content: 5 wt%), (b) polyethylene polymerized with a metallocene catalyst 5 parts by weight of polybutene-1 (melt index: 2 g / 10 min; melting temperature: 110 占 폚; density: 0.9110 g / ml) 3 parts by weight of an adhesive polypropylene polymerized with a metallocene catalyst (propylene-ethylene binary copolymer having an ethylene content of 5% by weight), an antioxidant, a neutralizing agent and a silica antilocking agent were mixed in an appropriate amount and placed in a Henschel mixer, The mixture was thoroughly mixed for 1.5 minutes under the conditions of 1,000 to 1,500 rpm and a polypropylene resin composition was prepared using a 40 mm single screw extruder with L / D 35 under the conditions of an extruder molding temperature of 160 to 210 ° C and an extruder molding speed of 100 rpm . Thereafter, the produced resin composition was formed into a film using a 40 mm uniaxially extruded film molding machine having L / D 35 at an extruder molding temperature of 160 to 210 DEG C and an extruder molding speed of 100 rpm.

Example  2

A film was prepared in the same manner as in Example 1, except that in Example 1, 86 parts by weight of the propylene-ethylene random copolymer (a) and 6 parts by weight of the adhesive polypropylene polymerized using the metallocene catalyst (d) .

Example  3

A film was prepared in the same manner as in Example 1, except that in Example 1, 83 parts by weight of a propylene-ethylene random copolymer (a) and 9 parts by weight of an adhesive polypropylene polymerized using a metallocene catalyst (d) .

Comparative Example  One

A film was prepared in the same manner as in Example 1, except that (b) polyethylene polymerized with a metallocene catalyst was not used in Example 1.

Comparative Example  2

A film was prepared in the same manner as in Example 1, except that 80 parts by weight of the propylene-ethylene random copolymer (a) and 12 parts by weight of the polyethylene (b) polymerized using the metallocene catalyst were used in Example 1.

Comparative Example  3

A film was prepared in the same manner as in Example 1, except that an ethylene-based alpha-olefin copolymer polymerized using Ziegler-Natta instead of the adhesive polypropylene in Example 1 was used.

Comparative Example  4

A film was prepared in the same manner as in Example 1, except that the propylene-based alpha-olefin copolymer polymerized by using Ziegler-Natta instead of the adhesive polypropylene in Example 1 was used.

The component compositions (unit: parts by weight) according to the above Examples and Comparative Examples are shown in Table 1 below.

Test Example

The properties of the films prepared according to Examples and Comparative Examples were evaluated according to the following methods, and the results are shown in Table 2 below.

[Assessment Methods]

1) Thermal Adhesion Temperature: The film was adhered at a constant temperature for 1 second under a condition of 2 kgf using a thermal adhesion tester, and the adhesive strength of the film was measured at a rate of 300 mm / min in a tensile tester, g was measured. The lower the thermal bonding temperature, the better the thermal adhesion.

2) SIT: The temperature at which the initial heat bonding starts, and the temperature at which a force of 100 g / 25 mm or more starts to be applied in the tensile tester is measured.

3) Haze: Measured according to ASTM D-746 as an indicator of transparency of the film.

4) Roll Mark: Judge whether the shape of the sweeper roll produced when the film is formed remains, and if it is not visually inspected, mark it as "○".

(B) a polyethylene polymerized by using a metallocene catalyst, (c) a polybutene-1 and (d) a metal (c) having a specific property according to the present invention. It can be confirmed that the film prepared by combining the optimal amounts of the adhesive polypropylene polymerized by using the hydrogenated catalyst has excellent transparency and processability and improved heat bonding related characteristics.

On the other hand, in the case of (b) not containing or excessively adding polyethylene polymerized by using a metallocene catalyst (Comparative Examples 1 and 2), it was found that the heat- It can be seen that the use of polypropylene (Comparative Examples 3 and 4) is unsatisfactory in both thermal adhesion properties, transparency and processability as compared with (d) the adhesive polypropylene polymerized using a metallocene catalyst.

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 (4)

(a) 86 to 96% by weight of a propylene-ethylene random copolymer containing 0.5 to 10% by weight of ethylene;
(b) 1 to 5% by weight of polyethylene polymerized using a metallocene catalyst;
(c) 1 to 5% by weight of polybutene-1; And
(d) from 2 to 6% by weight of an atactic polypropylene polymerized using a metallocene catalyst and having an ethylene content of from 2 to 10% by weight;
And a polypropylene resin composition. The method according to claim 1,
Wherein the propylene-ethylene random copolymer (a) has a melt index (190 占 폚, 2.16 kg load) of 1 to 15 g / 10 min and a soluble content of 2 to 8 wt%. The method according to claim 1,
Wherein the polyethylene (b) is in the form of a powder having a density of 0.930 to 0.950 g / ml and an average particle size of 5 mm or less and a melt index (190 占 폚, 2.16 kg load) of 1 to 30 g / 10 min. Composition. The method according to claim 1,
(C) the polybutene-1 has a melt index (190 占 폚, 2.16 kg load) of 0.4 to 5 g / 10 min, a melting temperature of 90 to 130 占 폚, and a density of 0.890 to 0.920 g / Propylene resin composition.