JPS5891772A - Composition for coating fluorocarbon resin - Google Patents

Abstract

PURPOSE:To provide the titled compsn. capable of forming a coating having excellent scratch resistance, smoothness and non-tackiness, by blending both micaceous iron oxide and mica particles with a fluorocarbon resin. CONSTITUTION:0.1-30wt% mixture of micaceous iron oxide and mica particles in a weight ratio of 1:7-7:1 is blended with a fluorocarbon resin such as polytetrafluoroethylene. The resulting mixture is uniformly dispersed in a liquid medium such as water to obtain a compsn. for coating fluorocarbon resins.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composition for coating a fluororesin, and more specifically, it contains mica-like iron oxide P and true mother particles to improve the scratch resistance and improve the smoothness and smoothness of the coating surface. The present invention relates to a fluororesin coating composition that provides an excellent non-stick coating.

Fluororesin is coated on cooking utensils to take advantage of its unique non-stick properties, but since this resin is a relatively soft synthetic resin, it is susceptible to scratches from metal spatula during use. It has its drawbacks. This drawback is 20
This becomes a problem because it is noticeable when used at high temperatures such as around 0''C.

Therefore, various methods have been developed to improve the scratch resistance of fluororesin coatings. One of them is JP-A-52
There is a method described in Japanese Patent No.-10386. This method is
Fluorine resin consisting of a base coat and a top coat derived from a transparent fluororesin dispersion +1 = coated article, the base coat consisting of a coating of fluororesin and mica particles, pigment-coated mica particles or metal flakes It is something to do. However, according to studies conducted by the present inventors, this coating film still does not have wear resistance that is satisfactory for practical use. The reason for this is thought to be that although the mica particles are flat and well dispersed in parallel to the direction of the coating film, they tend to be distributed in large quantities at the bottom of the coating film after coating and before drying, and the amount of distribution on the surface becomes small.

Furthermore, in the case of this composition, cracks tend to form in the coating film, resulting in poor thick coating properties. However, mica particles are relatively thin;
Moreover, it is flat and enters parallel to the direction of the coating film when applied, and rarely protrudes from the surface, so the surface smoothness is good, and as a result, the non-adhesiveness of the coating film is 11&r.

JP-A-56-108255 discloses a fluororesin coating composition containing mica-like iron oxide (hereinafter referred to as A/IIO) for the purpose of improving the scratch resistance of fluororesin coatings. is listed. This MIO is relatively flat and has high hardness (job hardness is 2.7 for mica).
~3.1, whereas in MIO it is around 5.5-65. ) Therefore, the scratch resistance of Nuri J can be sufficiently improved. However, MI(3)O is somewhat thicker than mica particles (for example, if mica is 0 or 1
~0.5 μm, whereas MIO is 0.5-5 μm.
It is m. 'fx thickness is 5 to 100 μm for both
Almost equal in degree. ), and because it is not completely flat,
A portion of M' IO protrudes from the coating film, and this uneven feeling tends to remain even after a top coat of fluororesin is applied. Therefore, the non-adhesive properties of the coating film inevitably become insufficient. Also, there is a problem in the thick coating property as well as in the case of mica particles.

The present inventors have conducted extensive research to improve the shortcomings of the prior art and develop a fluororesin coating composition that provides a coating film with excellent scratch resistance and surface non-stick properties. , MIO and true mother particle (hereinafter referred to as MICA)
It was unexpectedly discovered that by mixing and blending with a fluororesin, the scratch resistance and surface non-adhesiveness of the resulting coating film were improved, and the ability to coat thickly was also improved, leading to the completion of the present invention. Ta.

That is, the gist of the present invention resides in a fluororesin coating composition characterized in that MIO and MIGA are blended with a fluororesin at a weight ratio of MIO and IV7ICA of (4) 1 to 7:1. .

The MIO blended into the composition of the present invention is ferric monide (α-
A thin piece-like crystal whose main component is Fe203),
Those conventionally used as anti-corrosion pigments (coloring material No. 5)
(Refer to Vol. 2, p. 258 (1979)) and Tokuko Sho 4B-12
Synthesis α with smooth crystal planes as described in No. 485
- Iron oxide powder can be used. Since MIO is non-toxic and non-polluting, it can be mixed into 4ft wood such as cooking utensils without any problem.

The size of the MIO crystal flakes incorporated into the composition of the present invention is 5 to 100 microns, preferably 10 to 60 microns.

A conventional MIGA is used, and its surface may be coated with a pigment.

The ratio of MIO and MIGA is preferably 1=7 to 7:1 in terms of quantity ratio. If the amount of MIO exceeds this ratio, the smoothness of the coating film surface will be impaired, and if the amount of 1vIIO is less than this ratio, the scratch resistance will deteriorate.

The total blending ratio of mIO and fv'f I CA to the fluororesin is 0.1 to 3 () based on the weight of the fluororesin.
% by weight, preferably 1-10% by weight. If the blending ratio is too low, the abrasion resistance of the coating film will not be obtained, and if the blending ratio is too high, the non-adhesiveness of the coating t+'A will decrease, so both are not preferred.

In the present invention, fluororesin refers to homopolymers or copolymers of fluoroolefins such as tetrafluoroethylene, hexafluoropropene, chlorotrifluoroethylene, vinylidene 6 fluoride, or vinyl fluoride, and these fluoroolefins and ethylene. , a copolymer of beaten olefin of propylene (containing at least 75% by weight of fluoroolefin), among others, polytetrafluoroethylene, tetrafluoroethylene/hexafluoropropene copolymer, tetrafluoroethylene /Halufluoroalkylper7 /L/ Orovinyl ether copolymer, tetrafluoroethylene/
Tetrafluoroethylene polymers, such as ethylene copolymers, are preferred, and the flexibility does not exceed about 50μ;
Usually, those in the range of 01 to 50μ are used. A so-called dispersion produced by a conventional emulsion polymerization method has a particle size in the range of 0.1 to 3.0 μm, and can be suitably used in the composition of the present invention. Further, this dispersion is very advantageous because it can be used after being ground when producing the composition of the present invention. The amount of fluororesin in the composition of the present invention is usually 10
It may be up to 40% by weight.

As a medium for the composition, aqueous solution or an organic solvent may be used.
N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, methyl ethyl ketone, methyl glycol acetate, 2-nitropropane, ethylene glycol acetate, toluene, etc.) are used, and usually, The composition is prepared into an aqueous dispersion.

The composition of the present invention comprises a fluororesin, MIOp and MICA.
In addition to other additives, such as various interfaces (7), active agents (anionic surfactants, nonionic surfactants, etc.), pigments (titanium and iron oxides, etc.), viscosity adjustment and binding agents (methyl cellulose, ethyl cellulose)
, leveling agent (fluoroalkyl carbon ah etc.),
Containing a hardening agent (metal powder, metal compound, alkali or amine silicate, argyl silicate, silicon compound such as lithium borosilicate-1- or colloidal silica, etc.), wet ballast (organic solvent, etc.) I can do it.

The composition of the present invention comprises a fluororesin, MIO and MI
It is prepared by uniformly dispersing GA in the enclosure medium at the above blending ratio. In practice, fluororesin, M IO and MI
It is most convenient to prepare the GA as a liquid dispersion or solution, respectively, and to mix these. In addition, when the fluororesin used as a raw material is a powder, MIO and/or
For now, the former can be added to the aqueous dispersion of 1vII CA and mixed uniformly. In order to achieve uniform mixing, it is desirable to use a colloid mill, a ball mill, or the like.

(8) To form the composition of the present invention into an intermediate coat or top coat, apply the composition on the undercoat layer applied to the base material by spray coating or brush coating as in the conventional method. It can be painted using the birch method such as A fluororesin coating can also be formed on the substrate by thermocompression bonding a pre-formed fluororesin thin film onto the undercoat layer. The type of fluororesin used for this intermediate coat or top coat does not have to be the same as that used for the base coat, and may vary depending on the application.
The type of fluororesin for the two layers can be selected.

The fluororesin coating prepared in this way has improved scratch resistance and abrasion resistance, and is also excellent in non-adhesion.

Next, the present invention will be specifically explained by showing examples and comparative examples.

Examples 1 (1) to (9) and Comparative Examples 1 to 2 Polytetrafluoroethylene (Polyflon Dispersion D-1 (aqueous, solid content 60%) manufactured by Daikin Industries, Ltd.), the average major axis of the flakes was 5 MIO (
Kikuchi Color Industries Co., Ltd. [KS], also has an average major axis of 5 ~
Tianmu powder (US Meal Cor
poration) 2 and quaternary amine silicates (
(manufactured by Nissan Chemical Co., Ltd., solid content 30%) is mixed to the blending ratio shown in Table 1 below, and then an aqueous methylcellulose solution (solid content 5%) is added to adjust the viscosity, making it suitable for spray painting. A fluororesin composition is obtained.

Primer for fluororesin (Polyflon EK-17 manufactured by Daikin Industries, Ltd.) was applied to aluminum plates and aluminum frying pans whose surfaces had been sandblasted to 7 points.
83GB) and apply it so that the film thickness after firing is 7 to 12μ.

Next, the material is heated using an infrared dryer to sufficiently remove volatile substances, and then subjected to firing and fusing treatment for 20 minutes in an electric heating furnace maintained at 380°C.

Take the treated lozenges out of the furnace and let them cool at room temperature. A crushed fluororesin composition is first sprayed onto the primer film so that the film thickness after firing is 20 to 25 μm. Thereafter, drying and firing fusion treatments are performed in the same manner as in the case of the F primer.

Regarding the obtained coating film, -W type property, crack resistance, 111 Jt' abrasion resistance and durability were determined as coating film '1'.
91. Ta. The results are shown in Table 1.

Incidentally, the measurement of the physical properties of the coating was carried out by a different method.

Mold releasability: Fried egg test The υIJ was broken into a sample frying pan coated as described above and fried for 1 minute under normal cooking conditions, and the mold releasability of the υIJ was determined as follows.

◎: The omelette easily separates when the frying pan is turned upside down.

○: The omelette can be easily separated by just pushing it slightly to the side.

△: If you press it several times from around the omelet, it will release.

×: peeling, peeling 1. After that, it gets sticky.

Crack resistance: For this trial, four coated samples were made using the above method without using the above samples (aluminum plate, glue and frying pan).

Glass (length 5 cm x width 10 cyr + x thickness ζ 3 cyr), (11) The thickness after firing is less than 20μ, 20 ~
It was coated to a thickness of 40μ, 40-60μ and 60-80μ, dried and fired in the same manner as above.

The resulting coating (1) formed axis was evaluated according to the following criteria.

Less than 20μ × 20~40μ △40~6 (1
μ 0 60 to 80 μ ◎ After placing the sample on the abrasion-resistant air-heated hot plate and fixing it, the aluminum plate was heated to 200 ± 10°C, and a constant load was applied to this surface. The test is performed using a testing device that allows a metal spatula to be slid δ. The gold spatula has a width of 1
It is made of stainless steel with 5 holes and a thickness of 0.5111111,
301) Q
After 61 seconds (in the direction perpendicular to the width of the gold propeller), a reciprocating linear movement ω1 is performed (12) under a condition where a load of . Note that the tip of the gold spatula that comes into contact with the sample is polished so that it is perpendicular to the -measurement direction 7.

Using this test method, the degree of wear due to sliding and scratching of a metal spatula corresponding to approximately 2 years of use in general household cooking equipment is measured. The evaluation criteria in Table 1 are as follows! ￥]

◎: The delivered material was not exposed at all.

○: A very small amount of profiteer metal appears.

△: Base metal slightly exposed.

×: Base metal completely exposed.

In addition, nickel aluminide (Meteco 404 manufactured by Metco, USA) was sprayed to a thickness of 25μ on the same aluminum plate.
On top of this, apply a polytetrafluoroethylene primer (Polyflon EK-1788GB' manufactured by Daikin Industries, Ltd.).
) and top coat (ES-5 manufactured by Daikin Industries, Ltd.)
109BK) coated with a thickness of 10μ and 20~30μ respectively, the wear resistance is 2% according to the following standards.
It is △.

Durability: After using the sample frying pan and performing actual cooking that corresponds to one year of use under normal household cooking conditions,
The stickiness σ of the cooked food was determined and evaluated based on the following criteria.

○: Cooked food is not sticky.

△: Cooked food is slightly sticky.

×: The cooked food is quite sticky.

The results are shown in Table 1. In addition, in Comparative Examples 1 and 2, MI
Instead of using a mixture of O and mica powder, each was used alone.

Table 1 Note 1) Polytetrafluoroethylene Example 2 A primer for fluororesin (Die (15)) was applied to an aluminum plate and an aluminum frying pan whose surfaces had been roughened by sandblasting in the same manner as in Example 1.Polyflon manufactured by Kin Kogyo Co., Ltd. EK-1788GB) is painted, dried, fired, and fused. That's Yu's real sister example 1
The grading composition (2) was sprayed in the same manner as the primer in Actual Gun Example 1, and applied so that the film thickness after firing was 20 to 25 μm.
510OCR) and the film thickness after baking is 20~2
It was applied to a thickness of 5μ, dried, fired, and fused in the same manner as the primer.

The physical properties of the resulting three-layer coating film were tested by the method described in Example I. The results are as follows.

Mold release property ◎ Wear resistance ◎ Durability ○ Patent applicant: Daikin Industries, Ltd. Substitute Patent Attorney Aobai Ao (and 2 others) (I6) 577

Claims (1)

[Claims] 1. A fluororesin coating characterized in that a fluororesin is blended with mica-like iron oxide and mica particles at a weight ratio of 1 to 7:1. Composition for use. 2. The composition according to claim 1, wherein the mica particles are coated with a pigment. 8. The composition according to claim 1 or 2, wherein the total blending ratio of mica-like iron oxide and mica particles is 0.1 to 30% by weight based on the weight of the fluororesin. 4. The composition according to claim 3, wherein the total blending ratio of mica-like iron oxide and mica particles is 1 to 10% by weight based on the weight of the fluororesin. 5. The composition according to any one of claims 1 to 4Tti, wherein the fluororesin is a tetrafluoroethylene homopolymer or a copolymer.