JPH05112749A - Powdered polyethylene resin composition - Google Patents

Abstract

PURPOSE:To obtain the title compsn. for powder coating which gives a coating film excellent in slipperiness and surface gloss by compounding a resin mixture consisting of a specific ethylene-vinyl acetate copolymer and PE with a specified amt. of a fatty acid amide. CONSTITUTION:The title compsn. is prepd. by compounding 100 pts.wt. resin mixture consisting of 1-40wt.% ethylene-vinyl acetate copolymer and 99-60wt.% PE with 0.02-0.5 pt.wt. fatty acid amide (e.g. oleamide).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder polyethylene resin composition for powder coatings which, when used for coating, is capable of forming a coating film having good slipperiness and excellent surface gloss.

[0002]

2. Description of the Related Art Powdered polyethylene is known to be a material excellent in weather resistance, chemical resistance, impact resistance, etc., but powder coating with it gives high coating efficiency,
It is widely used for coating metal products such as household products and industrial products, because it has the advantages of being able to coat a thick film at once and being able to freely color it. In particular, for applications where slipperiness of the coating surface is required to improve stacking properties and workability of products, such as when a basket for bicycles is manufactured by a fluidized dipping method, conventionally, A method has been proposed in which a fatty acid amide such as oleic acid amide or erucic acid amide is added to a polyethylene powder resin as a lubricant (Japanese Patent Publication No. 53-1778).

However, when a fatty acid amide is added, bleeding out of the fatty acid amide may improve the slipperiness, but may cause a problem of lowering the gloss of the coated surface.
In order to prevent this, as an improved method of adding fatty acid amide, dry blending of fatty acid amide with a Henschel mixer etc. at a temperature above the melting point of the fatty acid amide and below the melting point of the resin shows the effect with a small addition By adding the fatty acid amide as much as possible to the resin, the fatty acid amide is dissolved in an organic solvent such as acetone and blended with the resin powder so that the fatty acid amide can be dispersed uniformly in the resin. There is known a method for preventing the presence of the above (Japanese Patent Laid-Open No. 58-176).
251 and JP-A-59-12954).

However, at present, it is not possible to prevent the deterioration of the surface gloss due to the bleed-out of the fatty acid amide to a satisfactory degree only by improving the method of adding the fatty acid amide.

[0005]

The object of the present invention is to overcome the above-mentioned drawbacks of the prior art, and to obtain a coating film which is excellent in slipperiness and has no deterioration in surface gloss due to bleed-out of fatty acid amide. There is a place to provide a powder polyethylene resin composition for powder coating.

[0006]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors, a resin mixture obtained by adding an ethylene-vinyl acetate copolymer (hereinafter, sometimes abbreviated as EVA) to polyethylene at a specific ratio was found. The inventors have found that a powder polyethylene resin composition for a powder coating which solves the above problems can be obtained by using a base resin and mixing it with a fatty acid amide in a specific ratio, and completed the present invention.

That is, the powder polyethylene resin composition for powder coatings of the present invention comprises (A) an ethylene-vinyl acetate copolymer having a content of 1 to 40% by weight of an ethylene-vinyl acetate copolymer and polyethylene. It comprises 100 parts by weight of a resin mixture and 0.02 to 0.5 parts by weight of (B) fatty acid amide.

The proportion of vinyl acetate in the ethylene-vinyl acetate copolymer is preferably 2-35% by weight.

Usually, when fatty acid amide is added to polyethylene for the purpose of improving slipperiness, since polyethylene has poor compatibility with fatty acid amide, the fatty acid amide bleeds out on the surface of the coating film to avoid deterioration of surface gloss. I couldn't. Therefore, it is very difficult to obtain a coating film having good slipperiness and not lowering the surface gloss. However, in the present invention, polyethylene is added with an ethylene-vinyl acetate copolymer showing a proper compatibility with fatty acid amide at a specific ratio, and therefore, when the composition of the present invention is used for coating. It has become possible to obtain a coating film having satisfactory performance in terms of both good slipperiness and prevention of deterioration of surface gloss.

The polyethylene used in the present invention is
Either low-density or medium-density polyethylene may be used, and one having a melt index (MI) of about 2 to 70 may be appropriately selected according to the purpose.

The EVA preferably has a vinyl acetate (VA) ratio of 2 to 35% by weight, and the melt index is preferably close to that of polyethylene to be used. If the proportion of VA is less than 2% by weight, the effect of suppressing the bleed-out of the fatty acid amide cannot be sufficiently obtained due to the poorly compatible ethylene component. When the proportion of VA exceeds 35% by weight, the compatibility with polyethylene deteriorates,
The surface condition after coating becomes poor and a smooth coating film cannot be obtained.

The fatty acid amide used in the present invention may be any oleic acid amide, erucic acid amide, linoleic acid amide, capric acid amide, stearic acid amide, etc., which is commonly used as a lubricant for polyolefin resins. Well, it can be appropriately selected according to the purpose of use.

As for the mixing ratio of polyethylene and EVA and the amount of fatty acid amide added, an appropriate composition is selected in consideration of the desired slipperiness and economical efficiency. That is, in order to suppress the bleed-out property of fatty acid amide, E
The mixing ratio of VA needs to be 1% by weight or more in the resin mixture. However, if the mixing ratio of EVA is too large, the deterioration of the surface gloss due to bleed-out is reduced, but in order to improve the slipperiness. It is necessary to increase the amount of the fatty acid amide as a lubricant added. Therefore, considering economic efficiency, the mixing ratio of EVA is 1 to 40 in the resin mixture.
% By weight. A preferred mixing ratio is 2 to 30% by weight.

The amount of the fatty acid amide added is selected in consideration of the mixing ratio of the resin mixture and the slipperiness and economical efficiency of the intended coating film as described above. An appropriate amount is 0.02 to 0.5 part by weight, preferably 0.1 to 0.4 part by weight, based on 100 parts by weight of the EVA resin mixture. This is because if the amount added is less than 0.02 part by weight, the slipperiness of the coating film is not sufficient, and if the amount exceeds 0.5 part by weight, the surface gloss of the coating film due to bleed-out is significantly reduced. .

As a combination of the mixing ratio of polyethylene and EVA and the addition amount of fatty acid amide, for example, when slipperiness immediately after coating is required to improve stacking property and workability, VA content is 10% by weight. % About 0.2 to 100 parts by weight of a resin mixture of polyethylene and EVA mixed with about 5 to 10% by weight of EVA.
When coating is performed using the one to which oleic acid amide is added in an amount of about parts by weight, it is possible to obtain a coated product having good slipperiness and long-term surface gloss.

The method of adding the fatty acid amide, which is a lubricant, is not particularly limited. For example, polyethylene and EVA may be added at the same time when they are mixed, or polyethylene and EVA may be mixed and ground into powder, and then blended using a mixer such as a V blender or a Henschel mixer.

As a method for mixing or kneading polyethylene and EVA, a usual method using a hot roll, a kneader, a Banbury mixer, an extruder or the like is applied.

In any of the methods, a colorant can be mixed in addition to the stabilizers, ultraviolet absorbers and other additives normally used in the mixing stage.

The coating method using the powdered polyethylene resin composition obtained in the present invention includes a fluidized dipping method,
There is no particular limitation on the electrostatic coating method, the glaze method,
It should be determined in consideration of the type, size, and economical efficiency of the product, but in general, the fluidized-bed method is often used.

[0020]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Examples 1 to 8 As shown in Table 1, low density polyethylene (trade name:
Sumikasen G804, Sumitomo Chemical Co., Ltd., MI = 3
0) 70-98 parts by weight of pellets and 10% by weight of VA content
2 to 30 parts by weight of EVA (trade name: Evatate D3010, manufactured by Sumitomo Chemical Co., Ltd., MI = 6), 2 parts by weight of carbon black as a pigment, and I as a stabilizer.
After mixing 0.1 parts by weight of rganox 1010 (manufactured by Ciba Geigy) with a 10 liter Henschel mixer,
The mixture was kneaded at 140 ° C. using an extruder having a diameter of 25 mm and L / D = 30, cooled with water and pelletized into a size of 2 mmφ × 3 mm.

40 obtained by mechanically grinding the pellets
100 parts by weight of powder of mesh pass and a predetermined amount of fatty acid amide (described in Table 1) were mixed with a Henschel mixer to obtain a powdered polyethylene resin composition.

Using the powdered polyethylene resin composition obtained above, a fluidized dipping method was performed under the following conditions: 2 mm × 7
It is coated on a steel plate of 0 mm x 150 mm and the film thickness is 0.
A 6 mm coating was obtained.

Flow-immersion condition Preheating of steel plate Furnace temperature 360 ° C. time 6 minutes Dipping time of steel plate 6 seconds Post-heating furnace temperature 180 ° C. time 2 minutes

The slipperiness, glossiness, surface condition and the like of the obtained coating were measured and evaluated by the following methods.
The results are shown in Table 1.

Evaluation of coating: Evaluation of slipperiness is performed by
Two coated steel sheets were superposed, and the sliding angle was measured at regular intervals after coating. Evaluation of gloss reduction due to bleed-out is 5
The specular glossiness at 60 ° was measured according to JIS K5400 for the accelerated sample (after 15 days) in a 0 ° C oven, and the specular glossiness was compared with that immediately after coating. The surface condition was evaluated by observing the surface with a micrograph and visually.

Example 9 EVA having a VA content of 5.2% by weight (trade name: Evatate CV5008, manufactured by Sumitomo Chemical Co., Ltd., MI = 2)
0) was used, and a powder polyethylene resin composition was obtained in the same manner as in Example 1 except that the composition ratio with polyethylene and the amount of fatty acid amide added were changed to those shown in Table 1. Using this, a coated product was obtained in the same manner as in Example 1 and evaluated. The results are shown in Table 1.

Example 10 EVA having a VA content of 28% by weight (trade name: Evatate H4011, manufactured by Sumitomo Chemical Co., Ltd., MI = 20)
Was used, and a powder polyethylene resin composition was obtained in the same manner as in Example 1 except that the composition ratio with polyethylene and the amount of fatty acid amide added were changed to those shown in Table 1. Using this, a coated product was obtained in the same manner as in Example 1 and evaluated. The results are shown in Table 1.

Comparative Examples 1 and 2 A powder polyethylene resin composition was obtained in the same manner as in Example 1 except that EVA was not mixed and the fatty acid amide was added in the amounts shown in Table 1. Using this, a coated product was obtained in the same manner as in Example 1 and evaluated. The results are shown in Table 1.

[0030]

[Table 1]

[0031]

When the powdered polyethylene resin composition of the present invention is used for coating, the obtained coating film has excellent slipperiness and is excellent in surface gloss reduction. Therefore, the powdered polyethylene resin composition of the present invention can be widely and suitably used for coating metal products such as household products and industrial products.

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C08L 23/08 LDJ 7107-4J

Claims (2)

[Claims] 1. 100 parts by weight of a resin mixture of ethylene-vinyl acetate copolymer and polyethylene, wherein (A) the content of ethylene-vinyl acetate copolymer is 1 to 40% by weight, and (B) fatty acid amide A powder polyethylene resin composition for powder coatings, which comprises 02 to 0.5 parts by weight. 2. The powder polyethylene resin composition for powder coating according to claim 1, wherein the proportion of vinyl acetate in the ethylene-vinyl acetate copolymer is 2 to 35% by weight.