JP2832631B2 - Non-charged colored molding - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a colored molded article of an ethylene copolymer having an antistatic property for a long period of time.

[Conventional technology and its problems]

Ethylene-vinyl acetate copolymer and ethylene- (meth)
Ethylene copolymers such as acrylate copolymers are flexible and lightweight, have excellent impact resistance, and are excellent in hygiene because they do not contain a liquid plasticizer, and are extruded instead of soft vinyl chloride resin. It is used for various colored molded products by injection molding and calendar molding. However, ethylene copolymers have the drawback that they have a large surface resistivity and are easily charged with static electricity compared to soft vinyl chloride resins.In practice, for example, in the case of artificial turf using ethylene / vinyl acetate copolymers, they can be used in winter. There has been a problem that an electric shock generated when a person grasps a metal handle of a door such as an entrance of a building due to static electricity generated when a person walks on artificial turf. Also, in the case of flexible containers made of ethylene-vinyl acetate copolymer, cutting waste and dust adhere to the product during the bag making process. In this washing operation, there is a problem that it is difficult to remove dust firmly attached due to static electricity and the operation is troublesome.

As one of the methods for solving such problems, there is a method of kneading an antistatic agent, but at present it has not been found that a satisfactory one has been found. That is, by incorporating the antistatic agent, the antistatic effect is maintained for a long time from the time of molding the molded body, and the pigment acts not only to prevent the surface of the molded body from whitening due to bleed out of the antistatic agent itself, but also to act as a pigment. It was necessary to satisfy various requirements, such as not disturbing the discoloration of the ethylene copolymer, without impairing the color tone and sharpness, and not promoting discoloration. Antistatic agents that have been used in molded articles have not met all of these requirements. For example, there is an example in which a nonionic surfactant such as a fatty acid sorbitan ester or a fatty acid glycerin ester is compounded as an antistatic agent in such a colored molded article. Such an antistatic agent exhibits antistatic performance by bleeding out to the surface of the molded product,
When the compounding amount is small, the antistatic agent is lost at an early stage due to bleed out, and there is a problem that the durability of the antistatic effect is short. On the other hand, when the blending amount is large, the amount of bleed out is large, and there is a problem that the surface of the molded body is whitened.

[Object of the invention]

The present inventors have conducted intensive studies to solve these problems, and as a result, have found that the purpose can be achieved by adding a nonionic surfactant having a specific composition. Accordingly, an object of the present invention is to provide an opaque colored molded article provided with an antistatic property for a long period of time without promoting a change in color tone or fading, and without an appearance change such as surface whitening. It is in.

[Summary of the Invention]

The present invention relates to a colored molded article of an ethylene copolymer containing a pigment, wherein a sorbitan / glycerin mixed polyol ester of hydroxy fatty acid (A) and a fatty acid polyol ester containing no hydroxy group (B) are mixed with 2/8 to 8 / The present invention relates to a colored molded article characterized by being mixed at a mixing ratio of 2 (weight ratio) and at a ratio of 0.1 to 5% by weight.

As the ethylene copolymer used in the present invention, ethylene-vinyl acetate copolymer, ethylene-vinyl ester copolymer such as ethylene-vinyl propionate copolymer, ethylene / methyl acrylate copolymer, ethylene / acrylic acid Ethyl copolymer, ethylene-butyl acrylate copolymer, ethylene-unsaturated carboxylic acid ester copolymer such as ethylene-methyl methacrylate copolymer, ethylene-
Acrylic acid copolymers, ethylene-methacrylic acid copolymers, and the like, ethylene-unsaturated carboxylic acid copolymers and sodium, magnesium, ionomers such as metal salts of zinc and the like can be exemplified, and particularly, flexibility, Moldability,
From the viewpoint of economy, an ethylene-vinyl acetate copolymer or an ethylene / unsaturated carboxylic acid ester copolymer is preferred.

In the ethylene-vinyl acetate copolymer and the ethylene-unsaturated carboxylic acid ester copolymer, the comonomer content of vinyl acetate and unsaturated carboxylic acid ester is 1 to 15%.
Mol%, preferably 1.5-10 mol%, melt flow rate (MFR) at 190 ° C, 1260 ° C load is 0.1-100 dg / mi
n ones are suitable.

In order to improve the physical properties of the ethylene copolymer used in the present invention, polyethylene, ethylene-α-olefin copolymer, polypropylene, ethylene propylene terpolymer or polypropylene and ethylene are used within a range not exceeding the amount of the ethylene copolymer. An olefinic thermoplastic elastomer composed of a blend of propylene terpolymers may be blended.

The ethylene copolymer of the present invention is colored by a pigment. The pigment may be an inorganic pigment or an organic pigment. For example, inorganic pigments such as titanium oxide, zinc white, graphite, and navy blue, and organic pigments such as azo-based, phthalocyanine-based, anthraquinone-based, perinone-based, perylene-based, thioindigo-based, isoindolinone-based, and quinacridone-based pigments. Is also good. The amount of the pigment is, for example, in the range of 0.1 to 5 parts by weight based on 100 parts by weight of the ethylene copolymer.

As the antistatic agent of the present invention, a sorbitan / glycerin mixed polyol ester of a hydroxy fatty acid (A) and a polyol ester of a fatty acid containing no hydroxy group (B)
And are used together. The hydroxy fatty acid in the component (A) has about 12 to 22 carbon atoms, is preferably a saturated one, and is more preferably hydroxystearic acid because it can be obtained at the lowest cost. As the fatty acid containing no hydroxy group in the component (B), those having about 12 to 22 carbon atoms can be used, and examples thereof include palmitic acid and stearic acid. Examples of the polyol component constituting the component (B) include glycerin, sorbitan, and those obtained by adding ethylene oxide or propylene oxide to these components in an amount of about 5 mol or less per mol.

The ratio of the components (A) and (B) used is 2/8 by weight.
88/2, preferably 3/7 to 7/3. The total amount of both components is 0.1 to 5% by weight, preferably 0.2 to 3% by weight.
It is. With such a use ratio, an antistatic effect is exhibited for a long period of time, and a whitening phenomenon, a change in color tone, and the like of a molding pair can be suppressed.

The molded article of the present invention may contain a weather resistance stabilizer, a lubricant, an anti-blocking agent, an inorganic filler, and the like, depending on the application, in addition to the pigment and the antistatic agent.

The colored molded article of the present invention is obtained by kneading an ethylene copolymer, a pigment, an antistatic agent, and other additives to be blended as necessary using a roll, a Banbury mixer, an extruder, and the like, and then performing extrusion molding. It can be obtained by molding into an arbitrary shape by a usual molding method such as injection molding or calendar molding.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, the antistatic performance lasts for a long time, and the colored molded object which does not whiten by the bleed-out is obtained. In addition, the dispersion of the pigment and the change of the color tone caused by the combination of the antistatic agent do not occur. Therefore, it is particularly suitable as a molded article that is exposed to outdoor wind and rain for a long time like an artificial turf, is repeatedly washed with water like a flexible container, and requires an antistatic effect for a long time.

 Next, the present invention will be described with reference to examples.

Examples 1 to 5 Comparative Examples 1 to 3 In Examples 1 to 5 and Comparative Examples 1 to 3, ethylene-
Vinyl acetate copolymer (Mitsui / Dupont Polychemicals product Evaflex P1905 Vinyl acetate content 19%, MFR 2.5g /
), A predetermined amount of glycerin monostearate and sorbitan-glycerin mixed polyol-hydroxystearate shown in Table 1 as an antistatic agent in a blue coloring masterbatch (copper phthalocyanine blue-blended ethylene / vinyl acetate copolymer). The added compound was kneaded with a two-roll mill to prepare a mixture, and a hot press (160 ° C.) was used to prepare a 0.5 mm-thick pressed sheet without color unevenness.

In order to evaluate the appearance of the press sheet and the durability of the antistatic effect obtained assuming the conditions of use of the flexible container, the above-mentioned press sheet was placed in a stirred 40 ° C warm water once a day. After immersion for a few minutes, it was repeatedly placed in an oven at 40 ° C. The presence or absence (distance to the sample: 2 cm) was evaluated.

Appearance ○ No abnormality × Whitening Adhered tobacco ash ○ No △ Slight × In Comparative Examples 1 and 2, the surface of the press sheet was whitened due to bleed out of glycerin monostearate, and
Comparative Example 2 with a small amount of glycerin monostearate
After 30 days, a small amount of tobacco ash adhered and the antistatic effect was reduced. In Comparative Example 3, although the press sheet surface did not whiten due to bleed-out of the sorbitan-glycerin-mixed polyol / hydroxystearate, tobacco ash adhered and did not show a sufficient antistatic effect.

However, Examples 1 to 3 in which two kinds of antistatic agents were used in combination showed a good antistatic effect without whitening of the surface of the press sheet and adhesion of tobacco ash.

In Examples 4 and 5 in which the additive of the antistatic agent is small,
Adhesion of tobacco ash to the press sheet surface was observed at an early stage, but after 7 days, as in Examples 1 to 3, there was no adhesion of tobacco ash and a good antistatic effect was exhibited. This is a phenomenon that occurred because it took some time for the antistatic agent to bleed out to the press sheet surface and exhibit the antistatic effect when the amount of the antistatic agent was small, and the ethylene copolymer There is no hindrance to the practical use of the molded product.

Examples 6 to 7 Comparative Example 4 In Examples 6 and 7, an ethylene-vinyl acetate copolymer (Evaflex P-1007, a product of Mitsui / Dupont Polychemical Co., Ltd., vinyl acetate content 10%, MFR 10dg / min) and green coloring required master were used. Batch (low-density polyethylene containing copper phthalocyanine green), antistatic agent and antioxidant shown in Table 2 (Ciba Geigy product Irganox 10)
10 0.1%, UV absorber (Ciba Geigy product Tinuvin 326) 0.1%, Light stabilizer (Sanol 770) 0.1%, Mold release agent (Nippon Seika product ELA) 0.08% are kneaded with a twin screw extruder. To make a formulation.

2m without color unevenness by injection molding using the obtained compound
A test sheet with a thickness of m is prepared and subjected to an outdoor exposure test (test location: Ichihara city, Chiba prefecture) assuming artificial turf. The appearance of the test sheet upon outdoor exposure, that is, whether there is whitening due to bleed out of the antistatic agent And antistatic performance, that is, Static
The change over time of the half-life of the charged static electricity by Honest meter Co., Ltd. (S-5109 type manufactured by Shishido Shokai, test condition distance: 20 mm, applied voltage: 10 KV) was measured.

Example 8 In Example 6, an ethylene-vinyl acetate copolymer (Evafres P-1407, a product of Mitsui / Dupont Polychemicals) was used.
Example 6 except that vinyl acetate content 14%, MFR 15 dg / min) 70 parts by weight, and linear low density polyethylene (Mitsui Petrochemical Co., Ltd., Ultrazex 20200J density 0.920 g / cm ² , MFR 18 dg / min) 30 parts by weight were used. A sample was prepared in the same manner as described above, and its performance was evaluated. The evaluation results are shown in Table 2.

Claims (1)

(57) [Claims] 1. A colored molded article of an ethylene copolymer containing a pigment, wherein a sorbitan / glycerin mixed polyol ester of a hydroxy fatty acid (A) and a polyol ester of a hydroxy group-free fatty acid (B) are mixed in 2/8 to 8/2
A colored molded article characterized by being mixed at a mixing ratio of (weight ratio) of 0.1 to 5% by weight.