JPS6017230B2 - Primer for enhancing the peel strength of fluorine-containing resin coatings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention significantly improves the bonding strength between the substrate and the coating when forming a fluororesin coating on the surface of a substrate such as metal, glass, ceramics, ceramics, etc. The present invention relates to an undercoat agent useful for enhancing the peel strength of fluororesin coatings.

A fluororesin, such as a heat-flowable fluororesin, is applied to the surface of a base material in the form of a powder, film, or dispersion, and the resin is melted under heat or under heat and pressure to form a fluororesin coating. It is known to form on the surface of the substrate.

When coating, lining, or bonding such a fluororesin film to a base material, various proposals have been made regarding surface treatment of the base material in order to improve the adhesive strength with the base material. At present, it is difficult to achieve a sufficiently satisfactory improvement in adhesive strength. As such a proposal, a very wide range of organosilicon compounds including aminosilanes,
That is, at least one or more primary to quaternary molecules in the molecule
class amino group and silicon-bonded functional group (denoted by Si-OR,
A method has been proposed in which a metal and a fluorine-containing polymer are bonded to each other via an organosilicon compound monomer or its polymer (R represents a hydrogen atom, an alkyl group, or an acyl group) (Hakamaseki Sho 50- No. 2036).

This proposal states that small amounts of surfactants, bases, and inorganic fillers may be added as additives to the solution of the organosilicon compound. however,
Just stating that small amounts of surfactants can be added;
What types of surfactants can be used without harmful effects, or conversely, what kind of descriptions do we have that give us hope that there may be some kind of improvement beyond the realm of passive usage where there is no harm? Neither the proposal nor the suggestion is disclosed in the above proposal. Special law related to applications filed by the same applicant 52-27 Sho.
No. 943 and Japanese Patent Application No. 113375 (1973)
(No. 142366), the applicant applied a surface treatment to the surface of a base material such as metal or glass with a silane coupling agent, and then prepared an electrostatically charged material with an average particle size of about 2 to about 15 caps and a porosity of 0.
．． We have discovered and proposed that a coating with improved adhesion between the base material and the resin coating can be formed by applying heat-flowable fluorine-containing resin powder under No. 74 and melting the resin powder.

Further research revealed that an aqueous solution containing aminosilanes and a specific surfactant, especially a cationic surfactant,
Approximately 1.5 times higher than when using aminosilanes alone
It has been discovered that it exhibits a surprising peel strength enhancement effect reaching about 2.3 tones or more. Furthermore, it has been found that such improvements are difficult to achieve in combination with other types of surfactants. Therefore, an object of the present invention is to provide an undercoat for enhancing the peel strength of fluororesin coatings, which exhibits excellent improvement effects.

The above objects and many other objects and advantages of the present invention will become more apparent from the following description. The undercoat of the present invention is an aqueous liquid consisting of aminosilanes and a cationic surfactant, and the aminosilanes include:
Aminosilanes having an amino group as a functional group for organic substances (a functional group for fluorine-containing resins) and a lower alkoxy group as a functional group for inorganic substances (a functional group for metals, glass, ceramics, ceramics, etc.) are preferred.

Specific examples of such aminosilanes include, for example,
r-aminopropyltriethoxysilane, N. 8(aminoethyl)-r-aminof. Aminosilanes such as lopyltrimethoxysilane can be mentioned. Examples of the cationic surfactants include amine salts containing primary to tertiary amines, quaternary ammonium salts, imidazolium salts, pyridinium salts, and quinolinium salts. Specific examples of such cationic surfactants include cationic surfactants such as lauryl dimethyl benzyl ammonium chloride and hexadecylamine fatty acid salts. These aminosilanes and cationic surfactants can be used alone or in combination. In the undercoat of the present invention, the aminosilanes in the aqueous liquid contain about 0.5
The content is preferably about 30% by weight, more preferably about 1% by weight to about 2% by weight, particularly about 1% by weight to about 1% by weight.

Also, the cationic surfactant is about 0.1 to about 1% by weight.
, even about 0.2-5% by weight, especially about 0.2% by weight
A preferable amount is about 2% by weight. If the amount is less than the lower limit of the above example, it will be difficult to obtain the desired peel strength enhancing effect, so if the amount is more than the above lower limit, it cannot be expected that the peel strength enhancing effect will further increase. Therefore, it is economically disadvantageous and there is no need to use an excessive amount. The undercoat for enhancing the peel strength of a fluororesin coating of the present invention is applied to a substrate to which a fluororesin coating is to be applied or formed, and the application means can be selected as appropriate.

For example, it can be applied by spraying, dipping, pouring, brushing or other means. As the substrate to which the undercoating agent of the present invention whose active ingredient is an aqueous liquid containing aminosilanes and a cationic surfactant is applied, a substrate made of a material having a heat resistance temperature equal to or higher than the melting point of the fluororesin is used, such as Examples include metal base materials such as iron, steel, aluminum, nickel, titanium, and zinc, and ceramic product base materials such as glass, ceramics, and ceramics. These base materials can be subjected to blasting treatment, power brushing treatment, solvent cleaning treatment, emulsion cleaning treatment, alkaline cleaning treatment, acid cleaning treatment,
It is desirable to have a surface that has been cleaned by applying dry firing treatment or other means in combination as desired. After applying the undercoat of the present invention to the substrate as exemplified above, a fluororesin is applied in any form, such as a film, sheet, flock, powder, etc., and heated to form a fluororesin coating. Alternatively, it can be bonded by applying heat and pressure.

At this time, the undercoat of the present invention applied to the substrate may be in a wet film state, or may be in a dry or bran state. Although such fluororesins can be selected and used as appropriate, in the present invention, it is preferable to use thermofluidic fluororesins. Examples of such heat-flowable fluororesins include tetrafluoroethylene copolymers, pinylidene fluoride polymers and copolymers, chlorotrifluoroethylene polymers and copolymers, and the like. Among these examples, as the comonomer of the copolymer, a copolymerizable vinyl comonomer having substantially no telogen activity can be used.

Examples of the above-mentioned vinyl comonomers that can be copolymerized with the above-mentioned tetrafluoroethylene, chlorotrifluoroethylene, vinylene fluoride, etc. include hydrocarbon-based olefins such as ethylene, propylene, isoptylene, etc.; vinyl fluoride; Fluorine-containing olefins such as vinylidene fluoride, chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, etc.; fluoroalkyl vinyl ethers such as perfluoro(methyl pynyl ether), perfluoro(propyl vinyl ether), etc. can be given. Among these thermofluid fluororesins, ethylene, tetrafluoroethylene copolymer (ETFE resin), tetrafluoroethylene/hexafluoropropylene copolymer (FEP resin), and barfluoroalkoxy resin (PFA resin) are particularly preferred. This can be cited as an example of a resin.

The thermofluidic fluororesin is preferably a powder with an average particle size of about 2 to about 15, more preferably a porosity of 0.
It is desirable that the powder has a total surface area of 74 or less and a total surface area of 10 or less. The heat-flowable fluororesin powder as described above in the present invention may contain a filler.

Examples of fillers include metals, glass, carbon, asbestos, mica, inorganic substances such as molybdenum disulfide, and fine powders of heat-resistant polymer compounds such as polyimide, polysulfon, and polyarylene sulfide. The fine powder may be in the form of fibers or flakes. On top of the undercoat of the present invention, a film of the fluororesin as described above is formed. At this time, a heat-flowable fluororesin with an average particle size of about 2 to about 15 caps, which is charged with static electricity, is applied. However, it is preferable to form a film by heating and melting it.

Such application can be carried out, for example, by electrostatic spraying, electrostatic dynamic immersion, electrostatic spreading, or any other suitable means.
The method of charging the resin powder is usually to apply a voltage to the powder from an electrode, but static electricity is generated by collision or friction between the powders or between the powders and a surface made of an electrically insulating material. It can also be charged. The electrode voltage required to charge the powder is approximately 3-15 KV.

By applying the fluororesin powder in this way and then heating and melting it to a temperature at which the resin powder melts, a fluororesin coating with improved peel strength can be formed.

In particular, heat-flowable fluororesin powder that satisfies the conditions of an average particle size of about 2 to about 15 mm, a porosity of 0.74 or less, and a total surface area of 10 mm or less per lump has no pinholes or In addition to having the advantage of being free from cracks and being able to form a coating with a smooth surface, it also has the advantage that it is possible to obtain a thicker coating film than before, if necessary. Coupled with the use of a primer, it is particularly useful for forming an excellent fluororesin coating. Hereinafter, examples of use of the undercoat of the present invention will be explained in more detail with reference to Examples as well as comparative examples.

Example 1 Wash with methyl ethyl ketone, then 35q
An aluminum plate with a length of 9 pieces, 3 pieces in length, and 1 piece in thickness was immersed in an aqueous solution of caustic soda for 3 minutes, washed with running water, and dried.
An aqueous solution containing 5% by weight of B(aminoethyl)r-aminopropyltrimethoxysilane and 0.2% by weight of lauryl dimethyl benzyl ammonium chloride was sprayed to adhere the silane and surfactant.

Next, PFA resin powder with an average particle size of 3 tsubo, a porosity of 0.49, and a total surface area of 0.5 tsubo/mm was applied to the wet aluminum plate subjected to the above treatment at an applied voltage of 10 KV and a discharge rate of 25 m/m.
After electrostatic spray painting with Jn, it was heated in an electric furnace at 330°C for 10 minutes to obtain a PFA resin coating. Further, two coats were applied under the same conditions as above to obtain a film with a thickness of about 30 mm. The coating had a smooth surface without pinholes or cracks, and its peel strength was 4.5k9/g.

Example 2 An aqueous solution containing 5% by weight of N.8 (aminoethyl)r-aminopropyltrimethoxysilane and 0.4% by weight of hexadecylamine acetate was applied to a steel plate that had been cleaned with methyl ethyl ketone, sandblasted, and then hollowed out. was sprayed to deposit the silane and surfactant.

Then, after drying the steel plate subjected to the above treatment, it was made into a PF with an average grain size of 3 tsubo, a porosity of 0.49, and a total surface area of 0.5 〆/ground.
A resin powder was applied at a voltage of 10 KV and a discharge rate of 30 m/min.
After applying static force adsorption coating, it was heated in an electric furnace at 330° C. for 10 minutes to obtain a PFA resin coating.

Furthermore, apply two coats under the same conditions as above to obtain a film thickness of approximately 300.
A final coating was obtained. The coating has a smooth surface without pinholes or cracks, and its peel strength is 6.
It was 0k9/Gaga.

Example 3 The same procedure as in Example 1 was repeated except that hexadecylamine acetate was used as the cationic surfactant in place of the cationic surfactant lauryl dimethyl benzine ammonium chloride. A film having a surface was formed.

Its peel strength was 4.2 kg/skin. Example 4 Instead of the cationic surfactant hexadecylamine acetate in Example 2, lauryl dimethyl benzyl
The same procedure was performed except that ammonium chloride was used, and a film with a smooth surface without pinholes or cracks could be formed.

Its peel strength was 6.2k9' skin. Comparative example 1~
4. In the case of forming a DFA resin film on an aluminum plate, the procedure of Example 1 was followed except that the other surfactants shown in Table 1 below were used or not.

Claims (1)

[Scope of Claims] 1. Peeling of a fluorine-containing resin film whose active ingredient is an aqueous liquid containing about 0.5 to about 30% by weight of aminosilanes and about 0.1 to about 10% by weight of a cationic surfactant. Primer for strength enhancement. 2 The average particle size of the film charged with static electricity is about 2 to about 150μ
The undercoat for enhancing peel strength according to claim 1, which is a coating formed by applying and melting a heat-flowable fluorine-containing resin.