JP2871948B2 - Polyphenylene sulfide resin-based powder coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyphenylene sulfide resin-based powder coating composition, and more particularly, to a smooth and uniform coating film having excellent adhesion even after baking for a short time, having no repelling on the surface. The present invention relates to a polyphenylene sulfide resin-based powder coating composition.

[0002]

2. Description of the Related Art Polyphenylene sulfide has high heat resistance,
Excellent properties such as water resistance, chemical resistance, abrasion resistance, and electrical insulation. For this reason, paints using this as a base resin are used in fields such as metal rust prevention, corrosion prevention, and electrical insulation treatment.

[0003] The coating material based on polyphenylene sulfide is usually formed by applying a powdery or slurry-like coating material on the surface of an object to be coated and then fusing it to form a coating film. Is sprayed on the surface of the preheated object to form a coating film. This is because polyphenylene sulfide has the property of being insoluble in any organic solvent.

[0004] In general, it is important that a paint has excellent adhesion to a substrate. This is the same in the case of polyphenylene sulfide resin-based paint,
In order for the coating film of polyphenylene sulfide resin coated on the base material to maintain excellent properties for a long time,
A prerequisite is that the adhesion between the coating film and the substrate is highly excellent.

In order to ensure adhesion to a substrate, it is necessary to apply a polyphenylene sulfide resin-based coating and then heat-treat (bake) the coating at a temperature not lower than the melting point of the polyphenylene sulfide resin for a long time. is there. Conventionally, regarding polyphenylene sulfide resin-based paint, 300 to
Baking is performed at a temperature of 400 ° C. for approximately 40 to 120 minutes. Various thermosetting paints currently widely used, for example, thermosetting acrylic resin paints,
Baking time of 5-20 for thermosetting epoxy resin paint etc.
Minutes, the baking time of the polyphenylene sulfide resin-based paint is very long.

[0006] In the coating of polyphenylene sulfide resin-based paint, high-temperature and long-time baking is required,
This is because, as shown below, if the printing is insufficient, a problem arises in terms of adhesion.

[0007] That is, when a coating product with insufficient baking is allowed to cool naturally after baking, the adhesion of the coating film becomes insufficient. Even if the adhesion of the coating film is good immediately after coating, the adhesion tends to decrease over time, and in extreme cases, the coating film is spontaneously peeled off from the substrate.

On the other hand, even if the baking is insufficient, if the film is quenched after baking, a coating film having excellent adhesion can be obtained. However, when the coated material is used at a high temperature of 100 to 250 ° C., In the meantime, the adhesion of the coating film is rapidly reduced, which is not suitable for the purpose of heat-resistant coating.

[0009]

The long baking time of 40 to 120 minutes after the application of the polyphenylene sulfide resin-based coating material causes a large decrease in the production efficiency of the coating. For this reason, the demand for polyphenylene sulfide resin-based coatings has been slow to expand despite having excellent coating performance.

An object of the present invention is to provide a polyphenylene sulfide resin-based powder coating composition which has excellent adhesion even after baking for a short time, has no repelling on the surface, and can form a smooth and uniform coating film.

[0011]

The polyphenylene sulfide resin-based powder coating composition of the present invention comprises a powder of aluminum dihydrogen tripolyphosphate 3 per 100 parts by weight of the polyphenylene sulfide resin powder constituting the composition. -50 parts by weight and 0-30 parts by weight of a fluororesin powder.

In the composition of the present invention, the surface is subjected to a hydrophobic treatment with a silylating agent, and the average particle size of the primary particles is 0.1.
Ultrafine particulate hydrophobic silica of 1 μm or less is 0.05 to
Preferably, it is contained at 0.6% by weight.

Further, the composition of the present invention comprises ultrafine aluminum oxide particles having an average primary particle size of 0.1 μm or less, and (weight of aluminum oxide) based on the ultrafine hydrophobic silica. / (Weight of hydrophobic silica) ≦
It is preferably contained at a ratio of 2.0.

First, the polyphenylene sulfide resin serving as the base of the composition of the present invention is:

Embedded image Is a repeating unit, and most of the terminals of the molecular structure are -SNa. Such a polyphenylene sulfide resin is disclosed, for example, in JP-B-45-336.
No. 8 or JP-B-52-12240.

[0015] The composition of the present invention also comprises a terminal SNa.
A polyphenylene sulfide resin in which a group has been converted to an SH group, or another polyphenylene sulfide resin can also be suitably used.

The polyphenylene sulfide resin constituting the composition of the present invention has a maximum particle size of 200 μm so as to be suitable for powder coating such as electrostatic powder coating, fluid immersion coating and thermal spraying.
Hereafter, it is more preferably 150 μm or less, and it is preferable to use a powder having an average particle diameter of 30 to 80 μm.

The aluminum dihydrogen tripolyphosphate used in the present invention is a compound represented by the chemical formula of AlH ₂ P ₃ O ₁₀ .2H ₂ O, and is a white fine powder that is hardly soluble in water. As the aluminum dihydrogen tripolyphosphate, those treated with silica, zinc, or the like can be suitably used in order to improve the stability to the resin and the dispersibility in the resin.

Aluminum dihydrogen tripolyphosphate can be produced, for example, by the method described in Japanese Patent No. 856386. As a commercial product, K-White # 8
2, # 84, # 84S, # 85, # 105 (all trade names manufactured by Teica Corporation).

The addition amount of aluminum dihydrogen tripolyphosphate is set to 3 to 50 parts by weight based on 100 parts by weight of the polyphenylene sulfide resin powder. 3 added
When the amount is less than the weight part, a coating film having good adhesion cannot be obtained by baking for a short time. If the amount is more than 50 parts by weight, the smoothness of the coating film will be significantly reduced. The preferable addition amount is 5 to 30 parts by weight based on 100 parts by weight of the polyphenylene sulfide resin powder.

The composition of the present invention may be used together with a fluororesin powder, if necessary. The fluororesin powder that can be used is not particularly limited. For example, PTFE (ethylene tetrafluoride polymer), PFA (ethylene tetrafluoride / perfluorovinyl ether copolymer), FEP (ethylene tetrafluoride / propylene hexafluoride copolymer), ETFE
(Ethylene tetrafluoride / ethylene copolymer) is a typical example.

The amount of the fluororesin powder added is 30 parts by weight based on 100 parts by weight of the polyphenylene sulfide resin powder.
Set to less than parts by weight. If the amount is more than 30 parts by weight, the smoothness of the coating film is significantly impaired, which is not preferable. When the fluororesin is added in the above range, the resulting coating film exhibits excellent properties such as non-adhesiveness and sliding property of the fluororesin, in addition to the excellent properties of the polyphenylene sulfide resin. A preferable addition amount is 20 parts by weight or less based on 100 parts by weight of the polyphenylene sulfide resin powder.

The composition of the present invention is characterized in that the repelling phenomenon occurring on the surface of the coating film (the coating material is repelled on the surface of the object to be coated, and dents (craters) and spot-like discontinuous portions on the coating surface are formed). In order to prevent the above, the surface is subjected to a hydrophobic treatment with a silylating agent, and the average particle size of the primary particles is 0.1%.
μm or less ultrafine hydrophobic silica is 0.05 to
It is preferable to contain 0.6% by weight.

The silylating agent is used for the purpose of stabilizing reactivity, treating surface hydrophobicity and the like by replacing active hydrogen such as hydroxyl group and amino group in an inorganic compound or an organic compound with an organic silicon group. Compound. Examples of the silylating agent include chlorosilanes such as dimethyldichlorosilane, trimethylchlorosilane, and n-butyldimethylchlorosilane; silazanes such as octamethylcyclotetrasilazane and hexamethyldisilazane; methyltrimethoxysilane, octyltrimethoxysilane, and the like. And the like alkoxysilanes. These silylating agents can be suitably used for producing ultrafine hydrophobic silica particles.

As the ultrafine-particle-like hydrophobic silica which has been subjected to a hydrophobizing treatment with a silylating agent, specifically, the following are commercially available. Aerosil R-805 as hydrophobized with an octyl group-containing silylating agent
Aerosil R-974 and Aerosil R-972 (both trade names, manufactured by Nippon Aerosil Co., Ltd.) as hydrophobized with a dimethyl group-containing silylating agent, and a trimethyl group-containing silylating agent. Aerosil R-812 (trade name, manufactured by Degussa Corporation) and the like subjected to a hydrophobic treatment are exemplified.

The addition amount of the hydrophobic silica is set to 0.05 to 0.6% by weight based on the whole composition. When the addition amount is less than 0.05% by weight, the effect of suppressing the repelling phenomenon at the time of coating is significantly reduced. On the other hand, when the addition amount is more than 0.6% by weight, the smoothness of the coating film formed on the surface of the work is impaired. The preferred amount is
0.1 to 0.5% by weight.

When a coating film having particularly excellent smoothness is required, the average particle size of the primary particles is preferably 0.1 μm or less, more preferably 0.005 μm, in addition to the hydrophobic silica. It is preferable to add ultrafine aluminum oxide particles having a particle size of about 0.05 μm. Examples of the ultrafine aluminum oxide include aluminum oxide C (trade name, manufactured by Degussa).

The amount of ultrafine aluminum oxide added in combination with the hydrophobic silica is preferably in the range of (weight of aluminum oxide) / (weight of hydrophobic silica) ≦ 2.0. If the amount of aluminum oxide exceeds the above ratio, the effect of adding the hydrophobic silica decreases, and repelling is likely to occur on the coating film surface, which is not preferable.
A more preferable ratio is (weight of aluminum oxide) /
(Weight of hydrophobic silica) ≦ 1.8.

The composition of the present invention may contain, if necessary, other additives, for example, coloring pigments such as titanium dioxide, red iron oxide (iron oxide), and carbon black; glass beads, glass powder, and glass short fibers. And inorganic fillers such as glass flakes, talc, calcium carbonate and barium sulfate; UV stabilizers; Further, other polymers such as polyamide, polycarbonate, polysulfone, polyethersulfone, polyphenylene oxide, polyimide, polyamideimide, and epoxy resin may be added.

The composition of the present invention comprises the components described above,
For example, it can be easily manufactured by mixing uniformly with a stirrer such as a Henschel mixer.

The composition of the present invention is applied to the surface of an object to be coated such as metal, glass or ceramic by a conventional powder coating method, and then baked at a temperature of 300 to 400 ° C. for a predetermined time. You. Prior to the powder coating, an appropriate primer may be primed on the surface of the object to be coated.

[0031]

The present invention will be described in more detail with reference to the following examples.

Examples 1 to 14, Comparative Examples 1 to 9 and Reference Example 1 Each component was blended according to the composition shown in Table 1 (units in Table 1 are parts by weight), and thoroughly mixed with a Henschel mixer. Thus, polyphenylene sulfide resin-based powder coating compositions of A to L were prepared. Among them, AF are compositions according to the present invention.

[0033]

[Table 1] The details of each component in the table are as follows.

Polyphenylene sulfide powder: Topren T-1 manufactured by Topren Co., Ltd.

Aluminum dihydrogen tripolyphosphate powder (1): K-White # 82, trade name, manufactured by Teica Corporation
(Surface treated product with zinc and silica), average particle size 5 μm.

Aluminum dihydrogen tripolyphosphate powder (2): K-White # 10, trade name, manufactured by Teica Corporation
5 (surface treated with zinc), average particle size 5 μm.

Fluororesin powder (1): manufactured by Kitamura Co., Ltd., trade name KTL-610 (PTFE), average particle size 10
μm.

Fluororesin powder (2): manufactured by Du Pont-Mitsui Fluorochemicals Co., Ltd., trade name MP-10 (PFA), average particle size 30 μm.

Hydrophobic silica fine powder: Aerosil R-974, trade name, manufactured by Nippon Aerosil Co., Ltd., having an average primary particle diameter of 12 μm.

Aluminum oxide fine powder: manufactured by Degussa, trade name: aluminum oxide C, average particle size of primary particles: 13 mμ.

Short glass fiber: manufactured by Nippon Sheet Glass Co., Ltd., trade name: Microglass Surface Strand REV9, fiber diameter 13 ± 1.5 μm, fiber length 35 ± 15 μm, average aspect ratio 2.7.

Using these compositions, coating and baking were performed as follows. First, thickness 0.5mm, length 150
The surface of a stainless steel plate (SUS304) having a width of 70 mm and a width of 70 mm was degreased with trichlene. Electrostatic powder coating was applied to the surfaces of the compositions A to L so as to have a thickness of 60 to 80 μm. Next, the coated product was placed in an oven set at a temperature of 350 ° C. and baked. At this time, as shown in Tables 2 and 3, the printing time was changed in a range of 5 to 60 minutes.
The coating was removed from the oven and allowed to cool naturally at room temperature.

[0043] The obtained coating film, adhesion immediately after coating, adhesion when left in 1 month at room temperature after coating, 20
After performing a heat resistance test for 100 hours in an oven at 0 ° C.
The adhesiveness, the presence or absence of a repelling phenomenon, and the degree of smoothness were evaluated.

The adhesion was evaluated according to the adhesion test method described in 8.5 of JIS-K5400. That is, using a cutter knife, make a cut to reach the object to be coated so that 100 squares are formed in a grid pattern with a gap of 1 mm, and a cellophane tape is placed on the squares of the coating. After bonding and peeling at once, the number of squares of the coating film remaining without peeling was counted. The result is expressed as (remaining squares) / 100. The presence or absence of the repelling phenomenon and the smoothness were visually observed. Here, the large number of repelling phenomena means 6 or more per coating plate. The results are shown in Tables 2 and 3.

[0045]

[Table 2]

[Table 3] From the results in Tables 2 and 3, the following can be understood.

In Comparative Examples 1 to 4 and Comparative Examples 7 to 9, since the aluminum dihydrogen tripolyphosphate was not blended, the initial adhesion was poor or the initial adhesion was low after a short baking time of 5 to 20 minutes. over time if even good sex
Alternatively, the adhesion is significantly reduced after the heat resistance test . For such coatings, in order to obtain a good coating adhesion, it is necessary prolonged baking for more than 40 minutes as shown in Reference Example 1, adhesion after heat resistance test even in this case Decreased
Tend to .

In Comparative Examples 3 and 4, the content of the fluororesin powder was too large, and in Comparative Examples 5 and 6, the content of the aluminum dihydrogen tripolyphosphate powder was too large, and in each case, the smoothness of the coating film was increased. Is significantly impaired.

In Comparative Example 7, since a fine powder of hydrophobic silica was blended, a coating film without repelling phenomenon was obtained. However, since no fine powder of aluminum oxide is blended, the smoothness is only good.
In Comparative Example 8, a coating film having excellent smoothness was obtained because aluminum oxide was blended. However, since no fine powder of hydrophobic silica is blended, many repelling phenomena have occurred. In Comparative Example 9, since neither the fine powder of hydrophobic silica nor the fine powder of aluminum oxide was blended, a large number of repelling phenomena occurred and the smoothness was only good.

On the other hand, in Examples 1 to 14, since an appropriate amount of aluminum dihydrogen tripolyphosphate powder was added, a coating film having excellent adhesion was obtained even when baked for a short time of 20 minutes or less. Does not decrease with time. The effect of rapid curing by the addition of such aluminum dihydrogen tripolyphosphate powder is similarly obtained even when only the polyphenylene sulfide resin powder is used, or when the polyphenylene sulfide resin powder and the fluororesin powder are used in combination. . Further, since the fine powder of hydrophobic silica and the fine powder of aluminum oxide are compounded, a coating film having no smoothing phenomenon and excellent in smoothness is obtained.

[0050]

As is apparent from the above description, when the composition of the present invention is used for powder coating, a smooth and uniform coating film having excellent adhesion even without baking for a short time and having no repelling on the surface can be obtained. Can be formed. This coating film makes use of the excellent properties of polyphenylene sulfide resin, which is the base resin, especially for heat- and chemical-resistant pre-coated boards, electric and electronic parts, electric insulating coatings such as electric wires, automobile parts, chemical plants, hot water pipes, It can be effectively applied to heat-resistant, chemical-resistant and anti-corrosion coatings for hot spring piping, ships / seawater plants, oil field pipes, etc.

Further, when the polyphenylene sulfide resin powder and the fluororesin powder are used in combination, the resulting coating film has not only the excellent properties of the polyphenylene sulfide resin but also the non-adhesiveness and sliding property of the fluororesin. It has excellent properties such as non-adhesive coating on electrical appliances, mechanical parts, food trays, etc., coating on various sliding parts,
It is suitable for electric insulation coating of electric wires. It is also effective as a primer for fluororesin coating.

Claims (3)

(57) [Claims] 1. Powder of polyphenylene sulfide resin 1.
3 to 50 parts by weight of aluminum dihydrogen tripolyphosphate powder and 0 to 3 parts by weight of fluororesin powder with respect to 00 parts by weight
A polyphenylene sulfide resin-based powder coating composition comprising 0 parts by weight. 2. The composition is subjected to a hydrophobizing treatment with a silylating agent and the primary particles have an average particle size of 0.1 μm.
The following ultrafine hydrophobic silica is 0.05 to 0.6.
The polyphenylene sulfide resin-based powder coating composition according to claim 1, which is contained by weight%. 3. Ultrafine aluminum oxide particles having an average particle size of primary particles of 0.1 μm or less, based on the weight of aluminum oxide / (weight of aluminum oxide) / hydrophobic silica.
The polyphenylene sulfide resin-based powder coating composition according to claim 2, which is contained in a ratio of (weight of hydrophobic silica) ≤ 2.0.