JPS5867738A - Polyethylene composition with improved clarity - Google Patents

Abstract

PURPOSE:The titled composition that is prepared by adding a nucleating agent to a low-density ethylene-alpha-olefin copolymer, thus showing eminently improved clarity, high strength, flexibility and being suitable for the use as a packaging material. CONSTITUTION:A copolymer from ethylene and an alpha-olefin (4-18 carbon atoms) with a basically straight chain structure and a density of 0.91-0.94 is combined with 0.1-2wt% of a nucleating agent. As the nucleating agent, is used an alpha- branched fatty acid, its metallic salt, polyhydroxypolyolefin, a copolymer of the polyolefin grafted with polycaproplatone of 20-60 polymerization degree on the chain termials, metallic salt of aromatic carboxylic acid and benzylidene sorbitol.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to polyethylene compositions with significantly improved transparency.

Polyethylene has traditionally been used for injection molding, as it has excellent chemical resistance, electrical insulation, and moldability, and also allows flexible products to be obtained without the use of plasticizers, and does not become brittle even at fairly low temperatures.
Polyethylene, which is formed into various molded products such as films and bottles by extrusion molding and blow molding, and is used in large quantities as packaging materials and household goods, is a homopolymer of ethylene, ethylene and other α-polymerized materials. - Copolymers with olefins.

Kinto, in the copolymer of ethylene and α-olefin,
α-olefin per 000 main chain carbon atoms, j
By introducing ~aO pieces, the density (ρ) becomes 0.2 ~
Polyethylene in the O, tag range is being produced and used in increasing amounts.

By molding low-density polyethylene, which is made of a copolymer of ethylene and α-olefin and is basically linear, it is possible to effectively increase the number of amorphous chains that bear external forces, thereby increasing the strength. It is known that high quality molded products can be obtained and molded products with better transparency than other polyethylenes can be obtained.

However, even molded products made from a copolymer of ethylene and α-olefin, which is basically linear low-density polyethylene, still have insufficient transparency depending on the application. , further improvement in transparency is desired.

Based on this background, the present inventors have determined that ethylene and α-
Consists of a copolymer with olefin.

As a result of intensive studies to obtain various molded products with extremely excellent transparency from essentially linear low-density polyethylene, we found that if a composition of the low-density polyethylene and a specific amount of a nucleating agent is made, The inventors have discovered that this object can be achieved and have arrived at the present invention.

That is, the gist of the present invention is to prepare a copolymer of ethylene and α-olefin with a density of 0.1 to 0.2 and a nucleating agent of 0.1 to 12. /~2% by weight of a polyethylene composition with improved transparency.

The present invention will be explained in detail below.

As mentioned above, the polyethylene used in the present invention is made of a copolymer of ethylene and α-olefin, and is basically a linear low-density polyethylene with a density of 0.2/-0 and a tag. be.

The α-odophins polymerized with ethylene are selected from straight-chain and branched hydrocarbons having a number of carbon atoms from μ to /f.

Examples of such hydrocarbons include butene-7, hexene-/, U-methylpentene-7, octene-7, decene-1, and the like.

On the other hand, a nucleating agent is a substance that is effective in growing crystals by becoming crystal nuclei, and if a nucleating agent is added during the molding process of a crystalline polymer, minute spherulites will form during cooling. A large number of products can be produced to obtain a homogeneous product. Suitable nucleating agents to be blended into polyethylene in the present invention are α-branched fatty acids, metal salts thereof, and poly-1-hydroxyboriolefin.

A compound obtained by block copolymerizing polycarboxylic acid with a degree of polymerization of 10 to 10 to the molecular terminal of the polyhedroxypolyolefin, a metal salt of an aromatic carboxylic acid, and a metal salt of an aromatic carboxylic acid. and benzylidene sorbitol.

Of these, 1 is polyhydroxypolyolefin.
Usually, a polyolefin having a hydroxyl group at the end of one molecule is used, and this material can be polymerized by a known method, for example, using hydrogen peroxide or the like as a polymerization initiator.

It can be obtained by hydrogenating a butadiene-based liquid polymer obtained by radical polymerization of butadiene alone or butadiene and a copolymerizable monomer.

Hydrogenation is carried out in a conventional manner using a nickel-based catalyst (for example, reduced nickel, Raney nickel), cobalt-based catalyst, platinum catalyst, palladium catalyst, rhodium catalyst, ruthenium catalyst, or a mixture or alloy catalyst thereof.

The blending ratio of such a nucleating agent to the copolymer of ethylene and α-olefin is 0. / ~ weight -.

If the blending ratio is less than 0.1 weight of ginseng, a nucleating agent is used.

The polyethylene composition of the present invention, in which such a nucleating agent is added to the copolymer of ethylene and α-olefin, can be molded into various molded products by a conventional method.

The film obtained from the polyethylene composition of the present invention is
It is extremely desirable as a packaging material because of its excellent transparency, high strength, and flexibility.

On the other hand, even molded products other than films can be expected to find wide use due to their excellent transparency.

Hereinafter, the present invention will be explained based on examples.

The present invention is limited to the examples unless it goes beyond the gist thereof.

Example 1 and Comparative Example 1 Melt index measured with JI8 K 6760 was 7. The O1 density was o and y2o, and was measured with a melt indexer. Stress to' dyne/c
d and i o' outflow ratio at a7ne/i- (hereinafter referred to as "
20 carbon atoms in the main chain, and 7 carbon atoms in the main chain.
As a nucleating agent for the α-branched fatty acid salt, an α-olefin mixture (with a carbon number of C0-C) was added to an ethylene-hexene-7 copolymer having VI-7 butyl branches per 000 units.
Diarenco Qt, Diaren is a registered trademark of Mitsubishi Chemical Industries, Ltd.) Sodium salt of K-propionic acid added f
O, J96 (weight) was blended.

The obtained polyethylene composition was heated to J at a resin temperature of 1°C.
Pelletization was performed using an Ovml extruder. The pellets were melt-pressed in a 26-ton press to a thickness of 100 mm.
A film of μ was obtained.The haze of the obtained film was measured using a turbidity meter (Model NDH-
-〇D, Nippon Denshoku ■) was used for measurement.

Haze represents the ratio of scattered light to total transmitted light, and the smaller this value (%) is, the more transparent the material is.

When no nucleating agent was added (comparative example/), the haze value decreased from J to 3%, and the effect of improving transparency is clear.

Comparative Example A film was produced under pressure in exactly the same manner as in Example 1, except that the amount of the nucleating agent was changed to o, ot% (by weight), and the haze was measured. As a result, the haze value was the same as Comparative Example 1 in which no nucleating agent was blended, and it was found that if the blending amount was less than 0.1% (weight), there was no effect of improving transparency. I understand.

Example 2~! A film was obtained in exactly the same manner as in Example I, except that the nucleating agent was changed to that shown in Table 1-#, and the haze of the film was measured in the same manner. The results are shown in Table 1.

Table-1 Example 6 and Comparative Example 3 J Engineering S Melt index measured with Kt7tO is K, j, density is O, Octopus! and νR- is /l and 'h seconds, and furthermore, for ethylene-butene-1 copolymer having ethyl branches per 1000 carbon atoms in the main chain,
As a nucleating agent for α-branched fatty acid salts, an α-olefin mixture with a carbon number of 30 or more (calculated from the weight value, 9 average carbon number reference J) (Daikiren 30.Diamond and Ren are Mitsubishi Chemical Corporation)
0.1% (by weight) of the sodium salt of propionic acid added to (registered trademark) was added.

The obtained polyethylene composition was heated at a resin temperature of 3° C.
Pelletization was performed using a 0.0-inch extruder. This beret 1
．． A film was formed using a 20 tt air-cooled inflation molding machine.

The molding conditions are as follows.

Molding machine: Thermoplastic, air-cooled inflation molding machine (I, /D = -7) Die: Spiral die, clearance / -
2NTR Nearing 2 1st stage temperature setting: 01200℃, 0 here 00℃, AD
Blow-up ratio: Cofrost line height = lJ Thickness: G Oμ Haze tube turbidity meter (Model NDH-CO01:1, Measured using a Nippon Denshoku (manufactured by Nippon Denshoku).

The haze of the haze that was dangerous due to the combination of a nucleating agent was 1 trqb (Comparative Example 3), whereas the haze of this example was 1 trqb, indicating an improvement in transparency.

Example 7~? A film was formed under the same conditions as in Example 6, except that the nucleating agent was changed to that shown in Table 2.

Applicant: Mitsubishi Chemical Industries, Ltd. Agent Patent Attorney Hase - 1 person Table - Ko

Claims (1)

[Claims] (1) Density is 0.21-0. A polyethylene composition with improved transparency, which is obtained by blending a nucleating agent fO/2 by weight with a copolymer of ethylene and α-olefin f. (2. The composition according to claim 1, in which the nucleating agent is an α-branched fatty thicket and/or a metal salt thereof. (3) The composition according to claim 1. A polyethylene composition in which the nucleating agent is poly-1 idroxypolyolefin. , a polyethylene composition which is a block copolymerized compound of polycarbonate and lactone having a polymerization degree of 10-aO. (5) In the composition according to claim 7, the nucleating agent is an aromatic carboxylic acid. A polyethylene composition which is a metal salt. (6) The polyethylene composition according to claim 1, wherein the nucleating agent is benzylidene sorbitol.