JPS5920363A - Powder coating composition - Google Patents

Abstract

PURPOSE:To provide a polyethylene powder coating compsn. excellent in powder characteristics, by incorporating a particular ethylene/alpha-olefin copolymer powder with a polyethylene or ethylene/alpha-olefin copolymer powder. CONSTITUTION:A compsn. which comprises 10-70pts.wt. ethylene/alpha-olefin copolymer powder whose bulk density is 0.25-0.55g/cc, angle of repose is 25-45 deg., particle size is 500mu or below and average particle size is 70-250mu, and shape is sphere, oval, or similar forms free from well-defined sides, edges, strings, or whiskers, and which is prepd. by suspension polymn. or gas phase polymn., and 90-30pts.wt. powder comprising a polyethylene or ethylene/alpha-olefin copolymer homogenized by melting and pulverized into 500mu or below.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyethylene powder coating composition having excellent powder properties.

High-pressure polyethylene resin is inexpensive and available in large quantities, and in terms of performance, it has excellent mechanical properties, water resistance, weather resistance, chemical resistance, electrical insulation, etc., and is also non-toxic and highly processable. Therefore, it is widely used as a powder industrial resin for fluidized dipping methods, electrostatic coating methods, etc. In addition, high-pressure polyethylene resin coatings are excellent in protecting and preventing corrosion of objects to be coated, but they are also excellent in decorating objects by coloring them in various colors.

However, when polyethylene resin powder is used for powder coating, not only the physical properties of the resin itself must be excellent, but also the powder characteristics of the powder must be excellent. For example, when used in a fluidized dipping method, if the powder properties are poor, a good fluidized bed cannot be obtained even when air is passed through, and the resulting powder film will be non-uniform. In addition, in the electrostatic coating method, if the powder properties are poor, it is difficult to transfer the powder from the powder storage tank to the coating gun, and the charged particles do not adhere uniformly, making it difficult to obtain a good coating film. do not have.

The general method for obtaining polyethylene 4-basin powder for powder coating is to knead and color the pigment and then obtain it by pulverizing means such as chemical pulverizing, freezing pulverizing, or room-temperature mechanical pulverizing.

Chemical pulverization can yield powder with good powder properties, but there are problems such as odor caused by residual solvent, deterioration of physical properties, and increased costs due to the use of solvents.

Freeze pulverization yields powder with good powder properties, but increases costs due to the use of a large amount of liquid nitrogen. Although mechanical grinding at room temperature can be carried out relatively inexpensively, the resulting powder has fibrous whiskers and has poor powder properties. Furthermore, by using a certain type of lubricant, a powder with good powder properties can be obtained by mechanical pulverization, but bleeding of the lubricant to the coating film interface becomes a problem.

Therefore, the inventors of the present invention have arrived at the present invention as a result of intensive research into a resin composition for powder coating that improves the powder fluidity of the powder obtained by such pulverization.

That is, in the present invention, (A) the bulk density of the powder is 0.25 to o, ss t/
cC.

(B) The angle of repose of the powder is 25 to 45 degrees. (C) The particle size of the powder is 500 μ or less, and the average particle size is 70 to 250 μ.
(D) The shape of the powder is spherical or elliptical, or
It has a shape similar to these, and is essentially free of clear edges, edges, and filamentous or whisker-like materials, and the tE+ powder is produced by suspension polymerization or gas phase polymerization. Ethylene-α olefin copolymer powder [A3
10 to 70 parts by weight and 8390 to 30 parts by weight of a powder obtained by powdering a melted and homogenized polyethylene or ethylene-α olefin copolymer to a size of 500μ or less ≠ Concerning a powder coating composition It is.

In the present invention, the ethylene-α-olefin copolymer powder [A] is a powder of a copolymer with an α-olefin containing 50 mol% or more of ethylene, and examples of the α-olefin include propylene, butene, etc. , pentene, 4-methylpentene-1, hexene, octene, etc.

These ethylene-α olefin copolymer powders CA'l
l may be a copolymer of two or more types of α-olefins, or may be a mixture of two or more types of ethylene-α-olefin copolymers. In addition, as α-olefin, 4-
High-grade α such as methylpente/-1, hexene, octene, etc.
Olefins are preferable because they have better coating MESCR properties. Such copolymer powder (A) can be produced by a method such as gas phase polymerization or suspension polymerization using a transition metal catalyst. The powder (A) is preferably a powder produced by polymerization, but it may also be a powder obtained by crushing a powder produced by polymerization, or a powder obtained by classifying such a powder.

In the present invention, the density of the copolymer powder [A) is
It is in the range of 0.910 to 0.935 t/cc, preferably in the range of 0.910 to 0.930 rz center.

The melt index (MI) of the above copolymer is 5 to
It is within the range of 1,009,710 m, and is more favorable, 10
A range of ˜5Qt/1Qsd* is preferable.

The bulk density of the copolymer powder [A] is 0.25 to 0.
In the range of 55f/CC, more preferably 0.35
A range of 0.45 is preferred. If the bulk density is higher than the above range, it becomes substantially difficult to manufacture the powder while satisfying the other powder properties of the present invention.

If the bulk density is lower than the above range, the workability will be lowered, pinholes will occur in the coating film, the color tone will be uneven, and the smoothness will be lowered, which is not preferable.

The angle of repose of the copolymer powder is preferably in the range of 25 to 45 degrees, more preferably in the range of 25 to 40 degrees.

If the angle exceeds 45°, the fluidity of the powder deteriorates, and the fluidity of the powder of the present invention is not sufficiently improved.

Further, if the angle is less than 25°, it becomes difficult to manufacture the powder while satisfying the other powder characteristics of the present invention.

In the present invention, the particle size distribution of the powder is JIS-Z880.
Sieve residue test method using No. 1 sieve (JIS
The test method defined by KOO69) provides a cumulative distribution curve. From this cumulative distribution curve, the diameter of the 50 percent value of the cumulative distribution, that is, the 50% particle diameter is determined as the average particle diameter. The particle size of the above copolymer powder [A] is 500
μ or less, and the average particle size is in the range of 70 to 250 μ. More preferably 300 μ or less and an average particle size of 100 to 25
A range of 0μ is preferred, −.

If the particle size is larger than the above range, the smoothness of the coating film will be impaired and the color tone will be uneven, which is undesirable. Undesirable.

In the present invention, the shape of the copolymer powder (A) is spherical, elliptical, or similar as shown in the photograph in FIG. It is necessary that it not be included in The powder obtained by mechanically crushing pellets at room temperature contains a considerable amount of thread-like or whisker-like substances, as shown in the photograph in Figure 2.
The shape of the powder particles also shows a complicated shape that looks like it has been torn off. In addition, the powder obtained by freezing and pulverizing pellets at liquid nitrogen temperature has a small amount of thread-like or string-like substances, but the powder particles have clear edges and edges.

If the powder particles have such a complicated shape, the effect of improving the fluidity of the powder of the present invention will not be exhibited.

The copolymer powder (A) may be colored with various colorants, or may be used as it is without being colored. Further, the copolymer powder [A) contains dibenzylidene sorbitol and/or its nuclear substituted product of 0.1 to 1.
0 parts by weight and 0.1 to 1.0 parts by weight of an antioxidant.

In the present invention, in the melted and homogenized polyethylene module or ethylene-α olefin copolymer powder [B], polyethylene refers to polyethylene produced by a high-pressure method and ethylene and vinyl esters containing 50 molti or more of ethylene. , acrylic esters, copolymers with vinyl monomers such as acrylic acid, and so-called ionomer resins made of partial metal salts of ethylene and acrylic acid copolymers.

In addition, in the melted and homogenized polyethylene or ethylene-α olefin copolymer powder [B], the ethylene-α olefin copolymer is an α-olefin copolymer containing 50 moles or more of ethylene that is polymerized using a transition metal catalyst. It is a copolymer with an olefin, and examples of the α-olefin include propylene, phthene, pentene, 4-methylpentene-1, hexene, and octene. Such copolymers can be produced by methods such as solution polymerization, gas phase polymerization, suspension polymerization, and polymerization in a high-pressure polymerization vessel.

Furthermore, the expression "melted and homogenized" refers to pellets that have been melt-kneaded using an extruder or the like. These melted and homogenized polyethylene or ethylene-α olefin copolymer powders [B]
may be used alone, may be a copolymer of two or more types of vinyl monomer and α-olefin, or may be a mixture of two or more types.

Densification of the above melted homogenized polyethylene or ethylene-α olefin copolymer, 0.910 to 0.9
35 y/cr, more preferably 0.9
A range of 10 to 0.930 t/cb is preferred.

Further, the MI of such polyethylene or ethylene-α olefin copolymer powder (B) is 5 to 100'/10
=, more preferably 10 to 50 t/10 ton.

The polyethylene or ethylene-α-olefin copolymer powder [B] may be colored with various colorants, and may be colored with dibenzylidene sorbyl and/or Tateya's Shojikyuken 0. 1 to 1.0 pages, and antioxidants 0.
It may contain 1 to 1.0 parts by weight.

In the present invention, the melted and homogenized polyethylene or ethylene-α-olefin copolymer powder [B) is
In order to impart adhesive properties, it is desirable to graft-modify the above copolymer with an unsaturated carboxylic acid or its acid anhydride. Examples of unsaturated carboxylic acids or their acid anhydrides include acrylic acid, methacrylic acid, maleic acid,
Possible examples include 7maric acid, itaconic acid, maleic anhydride, and itaconic anhydride, with maleic anhydride being particularly preferred.

These may be used alone or in a mixture of two or more. Further, in order to improve the grafting efficiency, vinyl monomers other than those mentioned above, such as styrene, vinyl acetate, acrylic ester, methacrylic ester, liquid rubber such as 1,2 polybutadiene, etc. can be used in combination. The amount of the above unsaturated carboxylic acid or its acid anhydride used is 0 for polyethylene or ethylene-α-olefin copolymer.
．． 01-3% by weight, more preferably 0.03-2% by weight
within the range of When the amount of modification is less than the above range, the effect of improving adhesion is poor, and when it is more than the above range, the adhesion is saturated and heat resistance etc. are rather deteriorated, which is not preferable.

Note that various methods can be used to prepare polyethylene or ethylene-α-olefin copolymer graft-modified with unsaturated carboxylic acid or its acid anhydride.

One method is to simultaneously mix the above-mentioned polyethylene or ethylene-α-olefin copolymer, unsaturated carboxylic acid or its acid anhydride, radical generator, and other additives as necessary, and conduct a melt reaction. The method is to add an unsaturated carboxylic acid or anhydride, a radical generator, to the polyethylene/or ethylene-α olefin copolymer dissolved or suspended in a suitable solvent,
There is a method of adding other additives and reacting as necessary. Further, the above polyethylene modified ethylene-α-olefin copolymer may be entirely modified, or a mixture of modified polyethylene or ethylene-α-olefin copolymer and unmodified polyethylene or ethylene-α-olefin copolymer. The above-mentioned melted and homogenized polyethylene or ethylene-α-olefin copolymer powder (B) is processed together with pigments and other additives in a single-screw or multi-screw extruder, Banbury mixer 1 hot roll, etc. A simple method is to heat, melt, knead, and then pulverize by mechanical pulverization such as cold pulverization or frozen pulverization using a mixer. Furthermore, in the case of powdering by chemical pulverization using a suitable solvent, it is also possible to mix the above-mentioned components in a solvent and then powderize.

The above melted homogenized polyethylene or ethylene
The bulk density of α-olefin copolymer powder (B) is 0.25
~o, ssy/cr, more preferably 0.30~o, 4sr/cr. Further, the angle of the powder [B] is in the range of 25 to 45°, more preferably in the range of 25° to 4o0.

The particle size of the powder [B] is preferably 500μ or less, more preferably 300μ or less, and the average particle size is 50~
A range of 250μ is preferred.

The powder coating composition of the present invention comprises the above-mentioned ethylene-α-olefin copolymer powder [A] and melted and homogenized polyethylene or ethylene-α-olefin copolymer powder (B).
) can be obtained by mixing.

Mixing methods include tumbler, ribbon blender,
Commonly used methods such as Henschel mixer etc. are possible. In particular, it is desirable to thoroughly mix the ingredients using a high-speed fluid mixer such as a Henschel mixer. The mixing ratio is 10 to 70 parts by weight of the above powder [A] and 9 parts by weight of the above powder (B).
It is in the range of 0 to 30 parts by weight.

When the amount of powder (A) is less than the above range, the color tone of the coating film and the powder properties are not sufficiently improved. If the amount of powder [A] is higher than the above range, uneven coloring of the coating film may occur, or [B
] If the gloss or human skin of the coating film of (A) is different from that of (A), the appearance will be non-uniform. In particular, in order to obtain a coating film appearance with a sense of depth, (A) should be 20 to 70 parts by weight, and CB and l should be 80 parts by weight.
~30 parts by weight is preferred, more preferably (A) is 3 parts by weight.
0 to 60 parts by weight, and 70 to 40 parts by weight of CB) are preferable.

Furthermore, in the present invention, ethylene-α olefin copolymer powder [A] and melt uniformity are used in order to obtain coating film ESCR, gloss, and dissimilar powders to appear uniform on the coating film, and to obtain a hue with a sense of depth. L<i>
It is preferable to add dibenzylidene sorbitol and/or its nuclear substituted product and an antioxidant to at least one of the d-ethylene-α-olefin copolymer powder [B].

The dibenzylidene rubyol used in the present invention is represented by the chemical formula % formula %), and the nuclear substituents of dibenzylidene sorbitol include methyl group, ethyl group, propyl group, isopropyl group, butyl group, Nuclear substituents such as methoxy, ethoxy, propoxy, butoxy, halogen, etc. are possible. These may be used alone or in combination of two or more.

In the present invention, the proportion of dibenzylidene sorbitol and/or its nuclear-substituted product used in the above powder [A] and [
B], for a total of 100 parts by weight, at least one of them contains 0
．． A preferable range is 1 to 1.0 parts by weight, more preferably a range of 0.2 to 0.6 parts by weight.

If the above usage ratio is less than the above range, the gloss of the coating film,
Improvements in smoothness, depth, and ESCR performance are inefficient,
In addition, if there is a large amount, the gloss, smoothness, depth, and ESC of the coating film
The effect of improving R properties becomes saturated and bleeds onto the surface of the coating film, impairing the appearance of the coating film, which is not preferable.

Examples of the antioxidant in the present invention include octadecyl 3-(3', 5' ditertiarybutyl 4' hydroxyphenyl) glopionate, tetrakis[methylene-(3,5-ditertiarybutyl 4hydroxyhydrocinnamate)] Methane, 2,2'-methy1/bis(
4-methyl-6-tert-butylphenol), 4.
4'-Butylidenebis(3-methyl-6-tert-butylphenol), 4,4'-thiobis(3-methyl-
6-tert-butylphenol), phenolic antioxidants such as 2.6-di-tert-butyl-p-cresol, dilaurylthiodipropionate, sulfur-based antioxidants such as dilaurylthiodipropionate%, tetrakis (2
, 4-ditertiarybutylphenyl) 4,4'-biphenylene diphosphonite, tris(2,4-ditertiarybutylphenyl) phosphite, and the like. Particularly preferred are phenolic antioxidants.

These antioxidants may be used alone or in combination of two or more.

In the present invention, the proportion of the antioxidant used in the powder [
A] and CB) in a total of 0.1 to 1. oi parts, more preferably 062~
It is in the range of 0.8 parts by weight, more preferably 0.3 to 0.3 parts by weight.
It is in the range of 0.6 parts. If the proportion of antioxidant used is lower than the above range, the physical properties of the coating film will be greatly reduced due to ESCR property, and if it is too large, the effect of improving the physical properties of the coating film will be saturated, and it will bleed onto the coating film surface. This is not desirable because it impairs the appearance of the paint film.

Although dibenzylidene sorbitol and/or its nuclear substituted product and antioxidant may be added individually, it is preferable to use them in combination. The above additives are added to either the ethylene-α-olefin copolymer powder obtained by polymerization [A] and the melted and homogenized polyethylene or ethylene-α-olefin copolymer powder (Bl VrC). or may be added to both.In particular, powder (A), [
In order to make 13'l of different types of powder look uniform on the coating film, it is desirable to mix and add the above additives to both powders [A] to CB). If the amount used is small, the coating film will appear uniform and the ESCR and gloss will be improved by simply adding it to the powder [B].

The method of addition is to melt and homogenize the polyethylene or ethylene-α-olefin copolymer powder [B] at the time of melting and homogenizing, at the time of pigment kneading, or at the time of graft modification with unsaturated carboxylic acid or its acid anhydride. You can also add
After pulverization, it may be added alone or simultaneously with the ethylene-α olefin copolymer powder (A).

In addition to the above composition, the powder coating composition of the present invention may contain ultraviolet absorbers, antistatic agents, lubricants, thickeners, coating aids, flame retardants, fillers, and other additives.

The powder coating composition of the present invention can be applied to metals, ceramics, and other materials by various powder coating methods such as fluidized dipping, electrostatic coating, electrostatic current dipping, thermal spraying, spraying, and rotational molding. can be painted. The object to be coated may be coated with an epoxy-based, urethane-based, or other primer, or may be subjected to a chemical conversion treatment, sandblasting, or other surface treatment.

The coating conditions for powder coating using the composition of the present invention are those commonly used in various powder coating methods, but preferably the temperature of the composition of the present invention is 20 degrees.
The temperature is preferably 0°C or higher, more preferably 2
Preferably, the temperature is 30°C or higher.

The thickness of a coating film coated using the powder coating composition of the present invention varies depending on the application, but is approximately 30 μm to 3 μm thick, and is usually in the range of 100 μm to IU.

The present invention will be explained below with reference to Examples.

In addition, parts in Examples and Soft Examples indicate parts by weight and weight %, respectively.

Further, the various properties that define the powder of the present invention were measured by the following methods.

Density: ASTM D1505 Melt index: ASTM D1238 Bulk density: ASTM D1895 Angle of repose: Measured by injection method.

Particle size distribution: JIS KOO69 Examples 1-1 to 3, Comparative Examples 1-1 to 3 MI 15 r/lo=, density 0.930 r/cc,
A suspension polymerization method in which the bulk density of the powder is 0.4217 momme, the angle of repose is 36°, the particle size is finer than 500μ, the average particle size is about 150μ, the shape is nearly spherical, and there is substantially no whiskers. Ethylene-butene-1 copolymer powder 1 obtained by
00 parts of dibenzylidene sorbitol, 0.4 parts of dibenzylidene sorbitol, and 04 parts of tetrakis[methylene-(3,5-ditertiarybutyl 4-bitroxyhydrocinnamate)]methane as an antioxidant were mixed using a Henschel mixer to form a powder [A]. ]
On the other hand, to 100 parts by weight of the above copolymer powder, 1.5 parts of carbon black, 0.4 parts of dibenzylidene sorbitol,
Tetrakis [methylene-(3,5-ditertiarybutyl 4-hydroxyno-1-hydrocinnamate)] as an antioxidant
] Pellets obtained by melt-kneading 0.4 parts of methane in an extruder are mechanically pulverized at room temperature, and the particle size is finer than 500μ, the average particle size is about 130μ, and the bulk density is 0.33 fμ.
A black powder CB) having an angle of repose of 42° was obtained.

The above powders [A] and [B] were mixed using a Henschel mixer at the blending ratio described in the first coating to obtain a powder for powder coating. Using this powder, the fluidized dipping method was used to obtain a thickness of 0.
8 places 1 length 150 fights, width 701! A coating film with a thickness of 0.3 parts m was formed on a JIS copper plate test panel (JIS G3141). The conditions for fluidized immersion are a bottom area of 200 cJ.
1 Kli powder was placed in a cylindrical fluidized tank, and the steel plate was preheated at 350°C for 4 minutes, fluidized immersion time was 2 seconds, and post-heated at 200°C for 3 minutes.

Coating film performance and F number of powder properties were determined as follows.

■Adhesion: A 90° peel test was performed by making a 10-part width cut in the coating. Chuck speed 50 m, m/familiarity ■ Paint film ESCR property: Painted test nozzle n = 10
The sample was bent 180 degrees at the angle, immersed in a 0.5% Antalox Co630 aqueous solution at 50℃, and the time until cracks appeared was measured. Time until cracks occur in 3 out of 3 pieces when n=6, ■Gloss: ASTM D52360°-60° ■Color unevenness Determine color unevenness with a second glance ○=Uniform, X=Uneven 0 Color depth feeling : Visually determined 〇 - There is a sense of depth. X
= No sense of depth.

■Fluidization immersion fluidization air amount: Recent air amount for uniform fluidization The results are shown in the first column.

Example 2 and Comparative Example 2 MI 17 r/10 standard, density 0.925 t/ct
The ethylene-butene copolymer powder obtained by the gas phase polymerization method was coarsely pulverized and classified to give a bulk density of o, 43y//
cC1 100 parts of powder with an angle of repose of 35°, a diameter of less than 500μ, an average particle size of about 150μ, a shape close to a sphere, and substantially free of whiskers, and dibenzylidene sorbitol 04 1 part, and 0.4 part of tetrakis[methylene-(3,5-ditertibutyl-4-hydroxyhydrocinnamate)]methane as an antioxidant were mixed using a Henschel mixer to obtain powder [A].

On the other hand, MI 20 f710, which is made by graft modification of 0.1% maleic anhydride, has a density of 0.923 t/c.
C solution polymerized ethylene-octene-1 copolymer 100
1.7 parts of titanium white, 0.4 parts of dibenzylidene sorbitol, and tetrakis[methylene-
(a, S-ditertiarybutyl 4-hydroxyno-hydrocinnamate)] Pellets obtained by melt-kneading 0.4 parts of methane using an extruder are mechanically crushed at room temperature to obtain a particle size of 500μ or more. A white powder [B] was obtained which was very fine and had an average particle size of about isoμ, a bulk density of 0.311, and an angle of repose of 43°.

The above powders (jl and [B] were mixed using a Henschel mixer at the mixing ratio described in the first coating to obtain a powder for powder coating. Using this powder, the same procedure as in Example 1 was carried out. Evaluation was carried out by the fluidized immersion method.The results are shown in Table 1.

Example 3 M I 20 r/xo, Agp density 0.923 y
The ethylene-butene-1 copolymer powder obtained by the gas phase polymerization method of /cr- was coarsely crushed and classified to have a bulk density of 0.41.
t/cc, angle of repose 35°, particle size finer than 500μ, average particle size about 180η7, spherical in shape and substantially free of whiskers, 100 parts of powder, and 0.0 parts of dibenzylidene sorbitol. Powder [A] was obtained by mixing 0.4 parts of tetrakis[methylene-(a, S-ditertiarybutyl 4-hydroxyhydrocinnamate)]methane as an antioxidant using a Henschel mixer.

On the other hand, MI 20 f710 m, density 0.919
y/ct: 100 parts of high-pressure polyethylene, 1 part of cyanine blue, and n-octadecyl a- as an antioxidant.
(3', 5' ditertiary butyl 4 hydroxyphenyl) propione) 0.4 parts and melt-kneaded using an extruder, the resulting pellets were crushed at room temperature to a particle size of 500.
It is finer than μ, with an average particle size of about 180μ and a bulk density of 0.
332/ Nod, a blue powder [B] with an angle of repose of 42° was obtained.

The above powders [A') and [B] were mixed using a Henschel mixer at the blending ratio shown in Table 1 to obtain a powder for powder coating. Using this powder, evaluation was performed by the fluidized dipping method in the same manner as in Example 1. The results are shown in Figure 1.

Comparative Example 3 In Example 1, MI ls was used instead of the ethylene-butene-1 copolymer powder (A) obtained by the suspension polymerization method.
y/lo =, density o, qaor/cc, bulk density of powder 0.28r/CC1 melt angle 49° particle size is 500μ
Ethylene-butene-1 copolymer powder obtained by a suspension polymerization method, which has a finer particle diameter of about 60μ, and has powder characteristics that include spherical shapes but often non-uniform shapes. The same procedure as in Example 1 was conducted except that a body was used.

The results are shown in Part 2.

Example 4 In Example 1-2, dibenzylidene sorbitol and tetrakis[methylene-(3,5-ditertiarybutyl 4-hydroxyhydrocinnamate)]methane in powder [A] and powder [B] were not added. is Example 1
A matte coating film was obtained in the same manner as in -2.

The results are shown in Table 1.

Comparative Example 4 100 parts of high-pressure polyethylene with an MI of 2817 m and a density of 0.915 y/cr, 1.5 parts of titanium white, and tetrakis[methylene-(3,5-ditertiarybutyl 4-hydroxyhydrocinnamate)] as an antioxidant. ] Pellets obtained by melt-mixing 0.4 parts of methane using an extruder are mechanically pulverized at room temperature to produce particles with a particle size smaller than 500μ, an average particle size of about 180μ, and a bulk density o, ao y. /
A white powder with an angle of repose of 44° was obtained.

When this powder was subjected to VC fluidization immersion in the same manner as in Example 1, the amount of fluidized air was 53 N17m, which was poor.

Margin below

[Brief explanation of the drawing]

Figure 1 shows polyethylene powder [A] used in the present invention.
Fig. 2 shows a scanning electron micrograph (magnification: 30x) of the powder [B] obtained by mechanically crushing the pellets. Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] 1. (A) The bulk density of the powder is 0.25 to 0.5.
5 seconds momme, (B) The angle of repose of the powder is 25 to 45°, (C
) The particle size of the powder is 500μ or less, and the average particle size is 70~
250μ, (D) The powder is spherical, elliptical or similar in shape and is essentially free of distinct edges, edges and filaments or whiskers; (E) The powder is free Powder of dry ethylene-α-olefin copolymer [10 to 0 parts by weight of Muco and melted homogenized polyethylene or ethylene-α-olefin copolymer] must be produced by turbid polymerization or gas phase polymerization. Powder coating composition 2 consisting of 90 to 30 parts by weight of powder [B] obtained by pulverizing a polymer to a size of 500 μm or less Powder [B) contains 0.01 to 0.01 to 0.01 to 300% of an unsaturated carboxylic acid or its acid anhydride The powder coating composition λ according to claim 1, wherein the powder (B) has a density of 0.910 to 0.935 seconds momme,
MI5~Zoo y/1o =, bulk density 0.25~0
．． Powder coating composition 4 according to claims 1 and 2, which has an effect of 5597, an angle of repose of 25 to 45 degrees, a particle size of 500 μ or less and an average particle size of 70 to 250 μ; Powder (A); The powder CBI contains dibenzylidene rubitol and/or its nuclear substituted product 0.
Powder coating composition 5 according to claims 1 and 2, comprising 1 to 1.0 parts by weight of an unsaturated carboxylic acid and 0.1 to 1.0 parts by weight of an antioxidant. or the powder coating composition according to claim 2, wherein the acid anhydride is maleic anhydride.