JPH0621242B2 - Polyolefin powder material for thermal spraying - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyolefin powder material for thermal spraying.

[Prior Art] In recent years, various structures and plants are required to have a long service life and durability under severe conditions. Therefore, various coating materials and coating methods have been proposed.

As the coating material, plastic such as polyethylene,
It has excellent corrosion resistance and is often used in the coating of steel pipes. As a method of coating these plastics, powder coating methods such as coating method, fluidized dipping method and electrostatic spray method are mainly applied to large equipment such as structures. Etc. are often used.

In addition, for the coating of metals and ceramics, the thermal spraying method is now widely used. The thermal spraying method mainly includes a gas thermal spraying method using a flame or an arc thermal spraying method using an arc, plasma, a laser, etc., which is a method of melting and spraying a coating raw material powder, and when a thermal spraying device such as a metal is directly used for plastics. However, the film was not able to be used because the film was greatly deteriorated by heat and the film had many defects. However, recently, a thermal spraying device for plastics has been developed, and thermal spray coating of plastics has also been performed.

[Problems to be Solved by the Invention]

However, even with the development of a device that causes less heat deterioration than a thermal spraying device for metals, etc., the plastics raw material powder is heated by thermal spray flames, etc., and is affected by a decrease in molecular weight, etc. It is above. For example, in Japanese Patent Laid-Open No. 60-153968, a substrate such as a steel pipe is coated with an adhesive primer in advance, and then polyethylene powder or the like is spray-coated to obtain a base material having a melting point up to the melting point of the coating material, which has been conventionally required. A method that does not require material preheating has been proposed. However, although a film having high adhesion and corrosion resistance can be obtained by this method, the raw material powder such as polyethylene is affected by heat, and in particular, cracks easily occur and resistance to cracking (hereinafter referred to as ESC) is particularly high. On the other hand, it is not enough.

It is an object of the present invention to provide a polyolefin powder material capable of thermally spray-coating various structures such as steel pipes and plants with polyolefin to obtain a film having a high density and a high ESC resistance, which is sufficiently suitable for use.

[Means for Solving the Problems]

According to the present invention, (a) (i) a modified polyethylene obtained by modifying at least one polyethylene selected from low-density polyethylene and linear low-density polyethylene with an unsaturated fatty acid and / or a derivative thereof, (ii) Elastic modulus 100-1 at room temperature
Elastomeric ethylene-butene-indicating 000 kg / cm ²
Provided is a polyolefin powder material for thermal spraying, which comprises one copolymer and (b) the ethylene-butene copolymer is contained in an amount of 40% by weight or more and 90% by weight or less.

Hereinafter, the polyolefin powder material for thermal spraying of the present invention will be described in more detail.

The modified polyethylene of the present invention is a polyethylene main chain grafted with an unsaturated carboxylic acid such as maleic acid, fumaric acid or itaconic acid and its anhydride or derivative, and the derivative also includes a metal salt of a carboxyl group. Is. It is also grafted with a vinylsilane compound such as vinyltriethoxysilane and methacryloyloxytrimethoxysilane. Among these modified polyethylenes, those obtained by grafting a modifying agent such as maleic acid, maleic anhydride, glycidyl methacrylate or hydroxyethyl methacrylate are preferable. The modification ratio is selected depending on the kind of the modifier and the ratio of the intended powder material to other compositions, and is usually 0.1 to 5% by weight.

In the powder material of the present invention, the modified polyethylene has an adhesive property due to the modifying group, so that the powder material can be provided with an adhesive property, and the adhesiveness of the thermal spray coating can be enhanced. In this case, the concentration of the modifying group relating to the modifying agent as the active site of adhesiveness may be, for example, at least 0.05% by weight as the content of maleic anhydride, and preferably 0.
It is 08 to 0.2% by weight. If it is less than 0.05% by weight, sufficient adhesiveness cannot be obtained.

Further, in the present invention, as the polyethylene, in addition to ethylene homopolyethylene of low density polyethylene, ethylene-α olefin copolymer such as linear low density polyethylene or vinyl acetate, copolymerized with non-olefin comonomer such as acrylate ester The resulting copolymer can also be used.

Furthermore, the modified polyethylene may include polyethylene modified with the above-mentioned modifier and unmodified polyethylene added as a diluent. In this case, as the powder-modified polyethylene to be added, linear low-density polyethylene is preferable in consideration of mechanical strength, compatibility, etc. of the obtained film. The amount of the unmodified polyethylene added is such that the modification rate of the modified polyethylene and the content of the elastomeric ethynylene-butene-1 copolymer are adjusted so that the concentration of the modification group in the powder material is within a range that can provide sufficient adhesiveness. It may be appropriately selected together.

The elastomeric ethylene-butene-1 copolymer of the present invention has an elastic modulus of 100 to 1000 kg / c at room temperature.
Any ethylene-butene-1 copolymer showing an elastomeric property at m ² may be used.

The ethylene content in the ethylene-butene-1 copolymer is
75 to 90% by weight, preferably 80 to 85% by weight
Is. Further, those having a melt index (hereinafter, simply referred to as MI) of 1 to 10 g / 10 minutes are preferable.
If the ethylene content is less than 75% by weight, the surface hardness is significantly reduced due to the decrease in crystallinity, and if it exceeds 90% by weight, the effect as an elastomer is reduced and the ESC is lowered, which is not preferable. Further, when MI is less than 1 g / 10 minutes, the resin fluidity in the film formation during thermal spraying decreases,
Along with that, defects such as generation of voids occur, which is not preferable.
On the other hand, when the MI exceeds 10 g / 10 minutes, the mechanical strength of the obtained film decreases, which is not preferable.

The polyolefin powder material for thermal spraying of the present invention contains the elastomeric ethylene-butene-1 copolymer in an amount of 40% by weight or more and 90% by weight or less. If the amount is less than 40% by weight, the ESC tends to be low, resulting in poor practicality. On the other hand, if the amount is more than 90% by weight, the depth of indentation of the coating is large and the surface hardness is unfavorably low.

The above-mentioned modified polyethylene used in the present invention, the unmodified polyethylene and the elastomeric ethylene-α oliphine copolymer may be obtained by a conventional method,
In addition, commercially available products may be appropriately selected and used.

The powder material of the present invention can be obtained by mixing and kneading the respective raw materials with various kneaders such as a Banbury mixer, a roll mixer, a kneader, a high-speed rotary mixer, an extruder and the like into pellets, and then pulverizing them. .

The particle size of the powder material for thermal spraying of polyolefin of the present invention is not particularly limited, but is usually in the range of 100 to 200 μm.

Furthermore, in addition to the above-mentioned raw materials, the polyolefin thermal spraying powder material of the present invention includes an antioxidant such as BHT, a coloring agent such as carbon black, a filler such as talc and mica, an ultraviolet absorber,
Various plastics additives such as lubricants may be added within a range that does not impair the purpose of the thermal spray coating of the present invention.

The thermal spraying using the polyolefin raw material powder for thermal spraying of the present invention can be carried out using any apparatus as long as it is an apparatus for plastics powder thermal spray coating. Further, after the surface roughening treatment such as sand blast treatment of the coated substrate to be sprayed, urethane resin, polyamine curing type epoxy resin, chloroprene-phenolic resin or other adhesive primer is applied in advance, and then spray coated. Adhesion can also be improved.

〔Example〕

Examples of the present invention will be described in detail below. However, the present invention is not limited to this embodiment.

Examples 1 to 3 and Comparative Examples 1 to 3 The surface of the SS41 steel material having a thickness of 6 mm was roughened by sandblasting to be SA2.1 / 2. An aromatic polyamine-curable epoxy resin was applied to the surface-roughened steel material to a thickness of 40 μm.

Then, the components having the composition ratios shown in Table 1 were mixed and then kneaded with a single-screw extruder to obtain a kneaded composition whose physical properties are shown in Table 2. The kneaded composition was further pulverized with a high-speed rotary pulverizer to obtain a thermal spraying powder having the powder physical properties shown in Table 3.

Further, the elastomeric ethylene-butene-1 copolymer is outside the scope of the present invention (Comparative Example 1), and the elastomer polyisobutylene is added instead of the elastomeric ethylene-α-olefin (Comparative Example 2). And ethylene-vinyl acetate copolymer added (Comparative Example 3)
Are similarly shown in Tables 1 to 3 for comparison.

The components used in the production of the thermal spray powder are as follows.

Modified polyethylene (modified PE): A polymer obtained by modifying linear low-density polyethylene manufactured by Ube Industries, Ltd. with 1% by weight of maleic anhydride.

Elastomeric ethylene-butene-1 copolymer (EE-α
-0): Mitsui Petrochemical Co., Ltd. linear low density polyethylene (LLDPE): Ube Industries, Ltd. polyisobutylene (PIB): Exxon Chemical Co., Ltd. ethylene-vinyl acetate copolymer (EVA): Ube Industries, Ltd. Each of the powders obtained as described above was spray-coated on the surface-treated steel material.

The thermal spray coating was performed using a plastic powder thermal spray coating apparatus CT-300 manufactured by Onoda Cement Co., Ltd., with the distance between the discharge gun and the coated steel material being 700 mm and the powder discharge rate being 200 g / min. Further, the steel material was preheated to 140 ° C. to have a sprayed coating thickness of 3 to 5 mm.

Table 4 shows the physical properties of the resulting sprayed coating.

In addition, each physical property value was measured by the following methods.

MI (g / 10 minutes): ASTM D1238 190 ℃ 2160g Softening point (℃): ASTM D1525 Oxidation induction period (minutes): 200 ℃ Measure the time to oxidative heat in an oxygen stream.

ESC (F ₅₀ (hr)): ASTM 1693 Measured by re-pressing the obtained thermal spray coating to form a sheet with a thickness of 3 mm.

Tensile properties (kg / cm ² ): ASTM D638 Bulk density (g / cm ² ): JIS K6721 Flowability: A perforated plate is provided at the bottom, and a 63 mm diameter, constant volume 78 cm ³ flow tank is provided to allow air to flow in from the bottom. Put a certain amount of powder material, the height of the powder layer from the perforated plate at rest (H 2 _O ),
The levitation ratio is the ratio (H _t / H _O ) to the height (H _t ) of the fluidized bed from the perforated plate when the fluidized bed begins to be formed by the inflowing air, and the air volume (cm ³ / min) at that time ) And display. The smaller the floating rate and the amount of air, the higher the fluidity of the powder material.

Medium particle size (μm): The particle size corresponding to 50% under the sieve in the particle size distribution.

Adhesion strength (kg / 10mm): Measure peel peel strength of JIS K6854 film.

As is clear from the examples and comparative examples, the skin covering obtained by thermal spray coating using the powder material of the present invention has high adhesion strength, high tensile strength and elongation, and good adhesion and flexibility. I understand. Also, it can be seen that the ESC is high and the application is excellent under severe conditions.

On the other hand, when the content of the elastomeric ethylene-butene-1 copolymer is 25% by weight, although the physical properties of the powder itself are relatively good, the obtained sprayed coating has good adhesion, but ES
It can be seen that C is low. Also, elastomeric ethylene
In the case of using PIB instead of butene-1 copolymer, the pulverizability was poor, the fluidity of the obtained powder material was low, the ESC of the thermal spray coating was low, and the tensile strength was high, but the film was not formed when measuring the adhesion strength. A break occurred. Further, the one using EVA has good fluidity and relatively high tensile strength and adhesion strength, but also has low ESC, and film breakage occurred at the time of measuring adhesion strength.

[Effects of the Invention] The present invention is a polyolefin powder material for spray coating a polyolefin coating on various structural materials such as steel materials. When the polyolefin powder material of the present invention is used for spray coating, a conventional plastic material is used. It is possible to obtain a polyolefin film having a higher stress cracking resistance than a spray-coated film of a sprayed film. Therefore, the thermal spray coating of the powder material of the present invention has long-term durability and can be applied to various plants under severe conditions.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenichiro Tomioka 1 Kimitsu, Kimitsu-shi, Chiba Nippon Steel Stock Co., Ltd. Inside the Kimitsu Works of Kaisha (72) Inventor Shoichi Adachi 8-1 Goi Minamikaigan, Ichihara-shi, Chiba Ube Kosan Co., Ltd. Chiba Petrochemical Factory (72) Inventor Tomio Ishida 8-1 Goi Minami Coast, Ichihara City, Chiba Ube Industries Co., Ltd. Chiba Petrochemical Factory (56) Reference JP-A-57-16069 (JP) , A) Japanese Patent Publication Sho 53-12945 (JP, B2)

Claims (1)

[Claims] 1. A modified polyethylene obtained by modifying at least one polyethylene selected from (a) (i) low density polyethylene and linear low density polyethylene with an unsaturated fatty acid and / or a derivative thereof, (ii) room temperature And an elastomeric ethylene-butene-1 copolymer having an elastic modulus of 100 to 1000 kg / cm ² at (b) 40% by weight or more and 90% by weight or less of the ethylene-butene-1 copolymer. Polyolefin powder material for thermal spraying.