KR100585330B1 - Polyolefin composition with improved melt properties - Google Patents

Abstract

The present invention relates to 100 parts by weight of polyolefin resin, 0.1 to 0.2 parts by weight of alkyl peroxide as a crosslinking initiator, and 0.2 to 2.0 parts by weight of pentaerythritol triacrylate as a crosslinking agent. It is about.

Description

Polyolefin resin composition excellent in meltability {POLYOLEFIN COMPOSITION WITH IMPROVED MELT PROPERTIES}

1 relates to a method for measuring deflection under high temperature.

The present invention relates to a polyolefin resin composition in which the physical properties of a molten state are greatly improved by reacting and crosslinking a monomer having a polyfunctional group with a polyolefin main chain.

Polypropylene has many useful properties, but its low melt properties due to its linear structure make it unsuitable for applications such as blow molding, foaming, vacuum forming or extrusion coating.

In order to solve this problem, Korean Patent Laid-Open Publication No. 96-34301 discloses a study to increase melt strength by mixing polypropylene and polyethylene, where melt strength means resistance when elongation or stretching occurs in a molten state. Although it has been published, polypropylene and polyethylene are inherently incompatible and the draw strength is higher than a certain degree has a disadvantage that the melt strength is lower than pure polypropylene.

In order to improve this problem, studies have been actively conducted to increase the melt strength of polypropylene itself. These studies have revealed methods for linking long side chains to polypropylene main chains, including the high energy electron beams in polypropylene in the absence of oxygen described in EP 0190889 A2 and 0384431A2. There is a method of producing polypropylene connected to long side chains by irradiation.

However, this method is limited to the polymorphic amorphous phase, creating a long side chain.

An object of the present invention is a polyolefin resin having excellent physical properties in the molten state by crosslinking by connecting a monomer having a polyfunctional group by applying a reactive extrusion method to a polyolefin having a low melt strength due to the linear chain structure It is to provide a composition.

The polyolefin resin composition having excellent melt state properties of the present invention is characterized by using a polypropylene or polyethylene as a main component alone or a mixture of the two, and a monomer having a peroxide as a crosslinking initiator and a polyfunctional group as a crosslinking agent.

As the main polyolefin resin used in the present invention, an ethylene-propylene block copolymer having a melt flow index of 0.2 to 15 g / 10 minutes at 230 ° C., a melt flow index of 0.3 to 15.0 g / 10 minutes and a specific gravity of 0.908 to 0.940 g / cm 3 Phosphorus polypropylene and high density polyethylene (HDPE) having a melt flow index of 0.2 to 2.0 g / 10 min and specific gravity of 0.940 to 0.970 g / cm 3 alone or a mixture of two or more thereof may be used. The polyolefin resin used in the present invention preferably has a melt flow index and specific gravity in the above range in order to obtain a polyolefin resin composition having excellent melt properties of the present invention.

As the peroxide used as the crosslinking initiator in the present invention, alkyl peroxide (R ¹ -OOR ² ; R ¹ , R ² is an organic radical group) is preferable in consideration of solubility with polyolefin, and particularly in the range of 135 to 155 ° C. It is preferable to have a half life of 1 hour. By way of example, dicumyl peroxide, tertiary butyl cumyl peroxide, bis butyl peroxy-isopropyl benzene and the like can be used, in particular products in which bis butyl peroxy-isopropyl benzene is present in the form of a 10% by weight master batch. Using is preferable because it makes it excellent in dispersibility and workability. The mixing amount of the crosslinking initiator used in the present invention is preferably 0.1 parts by weight to 0.2 parts by weight with respect to 100 parts by weight of the polyolefin resin as a master batch of 10% by weight. If the amount is less than 0.1 part by weight, no crosslinking reaction is formed during manufacture, and thus the physical and mechanical properties in the molten state are not improved. When the mixed amount exceeds 0.2 parts by weight, the cleavage of the molecule occurs during manufacture, and the physical and mechanical properties in the molten state are not improved. Peroxides used as cross-linking initiators generate harmful substances such as ketones and alcohols upon decomposition, so they must be released and removed during extrusion.

The crosslinking agents used in the present invention are monomers having a multifunctional group, and may include triallyl isocyanurate, (di) ethylene glycol di (meth) acrylate, trimethylolpropane, triacrylate, trimethylolethylene and triacrylate. , Divinyl pyridine, quinone dioxime, benzoquinone dioxime, p-nitrosophenol, N, N'-m-phenylene-bismaleimide, and the like, and examples thereof. In particular, polyfunctional (meth) acrylates (e.g., : Pentaerythritol triacrylate or trimethylol propane tri (meth) acrylate) is preferable. The mixing amount of the crosslinking agent is 0.2 to 2.0 parts by weight, preferably 0.5 to 1.0 part by weight based on 100 parts by weight of the polyolefin resin used. When the mixing amount is less than 0.2 parts by weight, crosslinking is not sufficiently formed, so that the physical and mechanical properties in the molten state are less improved. When the mixing amount is more than 2.0 parts by weight, it is difficult to obtain a resin composition having excellent molten state properties. .

In addition to the above components, additives such as antioxidants and lubricants may also be used in the resin composition of the present invention to improve processing characteristics. The antioxidant may be used alone or in the form of a mixture of two or more kinds of primary and secondary antioxidants, it is preferred to add 0.03 to 1.0 parts by weight.

The resin composition excellent in the physical property of the molten state of this invention can be manufactured by the following method. That is, a specified amount of polyolefin resin, an alkyl peroxide, a crosslinker monomer and various additives described above are charged into a stirring-mixer such as a Henschel mixer, a supermixer or a tumbler mixer and stirred for 1 to 10 minutes. -Mix. The mixture is melted and kneaded at a temperature of 180 to 230 ° C. using a rolling mill or an extruder to obtain pellets.

The present invention can be understood in more detail by the following examples and comparative examples, the following examples are only for illustrating the present invention and are not intended to limit the protection scope of the present invention.

The physical property measurement method used in the Example and the comparative example is as follows.

Property measurement method

1) Thermal Properties: Thermal properties were measured using a differential scanning calorimeter (DSC). A portion of the injection specimen was heated to 200 ° C. at an initial 20 ° C./min rate, and then cooled again to room temperature to measure the crystallization temperature (T _c ). And the melting temperature (T _m ) and the heat of melting (H _f ) was measured through the secondary heat treatment.

2) Melt Flow Index: The melt flow index of the extrudate was measured based on ASTM D1238 for a melt flow rate of 10 minutes under a load of 2.16 kg at 230 ° C.

3) Tensile strength: measured according to ASTM D638 test standard.

4) Heat deflection temperature: 127.0mm in length, 12.7mm in width and 6.4mm in thickness were molded using an injection molding machine and measured according to ASTM D648 test standard.

5) Surface hardness: measured according to ASTM D785 test standard.

6) IZOD impact strength: measured according to ASTM D256 (Notched) test standard.

7) Flexural modulus: measured according to ASTM D790 test standard.

8) Sagging at high temperature: A frame made by extruding a sheet having a thickness of 0.5 mm and a size of 30 × 30 cm, and a circular hole made of 20 cm diameter in the center of a 35 × 35 cm wood plywood was used. . The sheet was fixed between two layers of wooden frames, which were left in an oven at 220 ° C. high temperature, and after 5 minutes, the degree of deflection of the resin composition sheet was measured as a length (FIG. 1).

Comparative Example 1

Polypropylene resin, homogeneous polypropylene (HJ400; product manufactured by Samsung General Chemicals Co., Ltd.) with a density of 0.910 g / cm ³ and a melt flow index of 8.9 g / 10 minutes, 4.0 kg, Irganox 1010 4 g of antioxidant Ciba-Geigy as an additive 4 g of Songnox 1200, Songwon Industrial Co., and 4 g of calcium stearate as lubricants were charged to a Henschel mixer and stirred-mixed for 3 minutes. The resulting mixture was melt-extruded at 200 ° C. using an extruder with a diameter of 30 mm to prepare pellets. Physical properties of the prepared pellets were measured according to the above-described measuring methods, and the results are shown in Table 1 below.

Comparative Example 2

Except for using 6g of peroxide, the same components as in Comparative Example 1 were stirred-mixed under the same conditions as in Comparative Example 1, and then melt-extruded to prepare pellets, and the physical properties thereof were shown in Table 1. It was.

It can be seen from the result that the melt flow index increased significantly compared to Comparative Example 1, which is due to the molecular weight decrease of the polypropylene due to the cleavage of the polypropylene chain by the peroxide. In addition, the melting temperature and crystallization temperature of the polyolefin resin composition showed a tendency to decrease as the molecular weight of the polypropylene decreases.

Comparative Examples 3 to 5

The same components as those of Comparative Example 2 were charged to a Henschel mixer under the same conditions as those of Comparative Example 1, except that 0.25, 0.5, and 1.0 parts by weight of para-benzoquinone was used as a crosslinking agent with respect to the polypropylene resin used. After mixing, the pellets were prepared by melt-extrusion. The results of the measurement of the physical properties are shown in Table 1.

As para-benzoquinone was used as the crosslinking agent, the melt flow index increased compared to Comparative Examples 1 to 2, but there was little change in melting temperature or crystallization temperature and mechanical properties were not improved. This means that when para-benzoquinone is used in the above weight part as a crosslinking agent, no crosslinking or long chain linking reaction occurs.

Examples 1 to 3

The same components as in Comparative Example 1 were used except that 0.15 parts by weight of peroxide was used as the crosslinking initiator and 0.25, 0.5, and 1.0 parts by weight of pentaerythritol triacrylate as the polyfunctional crosslinking agent. They were charged in a Henschel mixer under the same conditions as in Comparative Example 1, stirred-mixed, and melt-extruded to prepare pellets to measure physical properties. The results are shown in Table 1 below.

The crosslinking with a certain amount of pentaerythritol triacrylate as a crosslinking agent significantly reduced the melt flow index and significantly increased the melting temperature and the crystallization temperature compared to the comparative examples. It can be guessed that this is due to the effective filling of the chains due to the limited chain motion. As such, crosslinking increased mechanical properties such as IZOD impact strength, surface hardness, elastic modulus, tensile strength, and heat deformation temperature.

Comparative Example 6

The same components as in Comparative Example 1 were the same as in Comparative Example 1 except that the polypropylene resin was replaced with 4.0 kg of crystalline ethylene-propylene block copolymer containing 11.0% by weight of ethylene and having a melt flow index of 0.59 g / 10 minutes. The pellets were prepared by charging the Henschel mixer under the conditions, stirring-mixing, and melt-extrusion, and the results of the measurement are shown in Table 2.

Comparative Example 7

The same components as in Comparative Example 6 were used in the same conditions as in Comparative Example 6 except that 0.3 part by weight of peroxide was used as the crosslinking initiator and 1.0 part by weight of pentaerythritol triacrylate was used as the crosslinking agent. It was charged to a Henschel mixer, stirred-mixed and melt-extruded to prepare a pellet, the physical properties were measured and the results are shown in Table 2.

Examples 4-6

Comparative Examples 6 and 0.1 were used, except that 0.10, 0.15, and 0.15 parts by weight of peroxide were used as crosslinking initiators, and 1.0, 1.0 and 2.0 parts by weight of pentaerythritol triacrylate, respectively, as the crosslinking initiator. The same components were prepared under the same conditions as in Comparative Example 6 and the properties of the pellets were measured and the results are shown in Table 2.

As a result of Table 2, when comparing Comparative Example 7 and Examples 4 to 6, the amount of crosslinking agent peroxide, which is higher than the appropriate amount, is more prevalent than the crosslinking. And it does not affect the improvement of the mechanical properties, which can be seen from the evaluation of the sagging of the resin composition sheet.

Comparative Example 8

2.0 kg of crystalline ethylene-propylene block copolymer containing 11.0% by weight of ethylene with polypropylene resin and melt flow index of 0.59 g / 10 minutes, and high density polyethylene with melt flow index of 0.35 g / 10 minutes by polyethylene resin (B220A; Samsung 2.0 g of General Chemical Co., Ltd. and 4 g of Irganox 1010, 4 g of Songnox 1200, Songwon Industrial Co., and 4 g of calcium stearate were charged to a Henschel mixer and stirred-mixed for 3 minutes. The resulting mixture was melt-extruded at 200 ° C. using an extruder having a diameter of 30 mm to prepare pellets. The physical properties were measured and the results are shown in Table 2.

Example 7

The same components as in Comparative Example 8 were used in the same conditions as in Comparative Example 8 except that 0.15 part by weight of peroxide was used as the crosslinking initiator and 1.0 part by weight of pentaerythritol triacrylate was used as the crosslinking agent. The pellets were prepared by charging a Henschel mixer, stirring-mixing, and melt-extrusion, and the physical properties thereof are shown in Table 2 below.

As shown in Table 2, the large decrease in the melt flow index and the low deflection at high temperatures have a significant effect on the crosslinking effect of the mixture of polypropylene and polyethylene by the use of the crosslinking initiator peroxide and the crosslinking agent pentaerythritol triacrylate. It shows that the physical properties of the molten state is improved.

Polypropylene (1): Homopolypropylene having a density of 0.91 g / cm ³ and a melt flow index of 8.9 g / 10 minutes.

                  (HJ400; Samsung General Chemical Co., Ltd. product)

Polypropylene (2): ethylene propylene block copolymer.

                  (Ethylene content; 11.0 wt%, melt flow index; 0.59 g / 10 min)

Polyethylene (1): High density polyethylene with a density of 0.958 g / cm ³ and a melt flow index of 0.35 g / 10 minutes. (B220A; Samsung General Chemical Co., Ltd. product)

Crosslinking agent (1): pentaerythritol triacrylate

Crosslinking Agent (2): Para-benzoquinone

Peroxide: Master batch of 10% by weight of 1,3-bis (t-butyl peroxy-isopropyl) benzene (Perkadox 14, manufactured by Akzo Chem.) As a crosslinking initiator.

As confirmed from the results of Tables 1 and 2, an appropriate amount of crosslinking initiator peroxide 1,3-bis (t-butyl peroxy-isopropyl) benzene and pentaerythritol triacrylate as a crosslinking agent was added. In the case of the embodiment of the present invention it can be seen that a resin composition having excellent melt physical properties and mechanical properties can be obtained.

On the other hand, when only peroxide is added and no crosslinking agent is added (Comparative Example 2), or para-benzoquinone which is a polyfunctional monomer as a crosslinking agent (Comparative Examples 3 to 5) and the peroxide is 0.3 parts by weight or more When excessively applied (Comparative Example 7), it can be seen that the melt properties and mechanical properties of the final resin composition are significantly reduced.

As can be seen from the above, the polyolefin resin composition prepared according to the present invention has excellent suitability for use in vacuum molding, foam molding, etc. by attaching a long side chain to the main chain to the polyolefin or crosslinking between chains, It has the advantages of excellent mechanical properties such as melt properties and tensile strength, bending strength and heat resistance in the state.

Claims (4)

With respect to 100 parts by weight of polyolefin resin, 0.1 to 0.2 parts by weight of an alkyl peroxide 10% by weight masterbatch as a cross-linking initiator, and 0.2 to 2.0 parts by weight of a monomer having a polyfunctional group as a crosslinking agent, excellent melt state properties Polyolefin resin composition. According to claim 1, wherein the polyolefin resin is polypropylene having a melt flow index of 0.3 ~ 15.0g / 10 minutes, specific gravity 0.908 ~ 0.940g / cm ³ , melt flow index of 0.2 ~ 2.0g / 10 minutes, specific gravity 0.940 ~ 0.970 A polyolefin resin composition having excellent melt state properties, characterized in that at least one member selected from the group consisting of high density polyethylene having a g / cm ³ and an ethylene-propylene copolymer having a melt flow index of 0.2 to 15 g / 10 minutes. The polyolefin resin composition having excellent melt state properties according to claim 1, wherein the crosslinking initiator is dicumyl peroxide, tertiary butyl cumyl peroxide, or bisbutyl peroxy-isopropyl benzene. The crosslinker according to claim 1, wherein the crosslinking agent is triallyl isocyanurate, (di) ethylene glycol di (meth) acrylate, trimethylolpropane, triacrylate, trimethylolethylene, triacrylate, divinyl pyridine, quinone Dioxime, benzoquinone dioxime, p-nitrosophenol, or N, N'-m-phenylene-bismaleimide, The polyolefin resin composition excellent in the molten state physical properties.

Images