JPS5853671B2 - Fluoro rubber water-based paint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a fluororubber aqueous paint, particularly a fluororubber aqueous dispersion, containing a specific aminosilane compound that binds the molecular terminal (amine group), which has improved adhesion to a substrate. The present invention relates to fluororubber water-based paints.

Due to the excellent heat resistance, weather resistance, oil resistance, solvent resistance, and chemical resistance of fluororubber, fluororubber paints can be applied or impregnated onto various substrates such as textiles, fibers, metals, plastics, rubber, etc. It is widely used as an industrial material.

Conventionally, so-called solvent-based fluororubber paints, which are made by adding an aminosilane compound as a vulcanizing agent to a composition containing fluororubber and an organic solvent to improve adhesion to a substrate, are already known (for example, (See Special Publication No. 47-18346).

However, so-called water-based fluororubber paints that are satisfactory in terms of adhesion to substrates have not yet been proposed.

The inventors of the present invention have conducted extensive research with the aim of developing a water-based fluororubber paint with excellent adhesion to substrates, and as a result of the above-mentioned solvent-based fluororubber paint, as will be detailed later. Among the aminosilane compounds used in rubber paints, only a specific aminosilane compound that binds an amine group to the end of the molecule can provide a good water-based fluororubber paint without causing gelation. Compared to the above-mentioned solvent-based fluororubber paints, the pot life is significantly improved, and even when spray painting with a high fluororubber concentration, there is no stringing phenomenon, making it extremely advantageous to apply paint. Furthermore, we have obtained a completely new finding that the above-mentioned technical effects are more desirably achieved when using the specific aminosilane compound that has been partially or completely hydrolyzed with water. As a result, the present invention was completed.

That is, the gist of the present invention is to add the general formula H2N-X-R'' Si (OR) yR' (3
-y) [In the formula, R is -CH3 or -C2H5, π is CH3,
W is -C3H6-1X is a single bond, +C2H, -NH9-
1-(C-NH+ or (-C2H, -NH-C2H,
-NH-) y is 2 or 3.

A water-based fluororubber paint containing an aminosilane compound represented by the following formula or a partial or complete hydrolyzate thereof.

According to the present invention, however, when the aminosilane compounds used in the solvent-based fluorocarbon paint are used in the water-based fluoro-rubber paint, not all of the aminosilane compounds provide a good fluoro-rubber paint. However, when a specific aminosilane compound that binds the amino group at the end of the molecule is used, an unspecified type of aminosilane compound causes the paint to gel, but when a specific aminosilane compound is used that binds the amino group at the end of the molecule, a good result can be obtained without causing the gelation disadvantage. A fluororubber water-based paint can be obtained.

Regarding pot life, solvent-based fluororubber paints usually gel at 25°C in about 10 hours and become unusable, whereas the water-based paints of the present invention have a long pot life of 2 weeks to 1 month (difficult). It is very stable and easy to handle during painting.

Furthermore, in the case of spray painting (in this case, in the case of solvent-based fluororubber paints, if the fluororubber concentration is increased to 20% by weight or more, stringing will generally occur and the fluororubber will become unusable for a long period of time. % by weight or less, or
Another drawback is that a fluororubber with a relatively low molecular weight must be used.

On the other hand, with the water-based paint of the present invention, spray painting is possible without any abnormality even at a fluororubber concentration of up to 60% by weight, and therefore it is easy to obtain a thick paint film.

Note that water-based paints for fluororubber have been known in the past, in which a polyamine compound (for example, hexamethylenediamine turbamate, N,N-dicinnamyrite 1,6-hexanediamine, etc.) is used as a vulcanizing agent in an aqueous dispersion of fluororubber. However, satisfactory adhesion to the base material cannot be obtained, and therefore preliminary treatment is performed to increase adhesion (for example, the metal surface is roughened by blasting).

), and it was necessary to use a suitable adhesive.

However, according to the present invention, it is possible to obtain a cured coating film of fluororubber with sufficiently excellent adhesive strength to the substrate without requiring such pretreatment or adhesive.

The fluororubber used in the present invention is a highly fluorinated elastic copolymer, and particularly preferred fluororubbers include vinylidene fluoride and at least one other fluorine-containing ethylene copolymerizable with vinylidene fluoride. Examples include elastic copolymers with sexually unsaturated monomers.

Further, as the fluororubber, fluororubber containing iodine in the polymer chain can also be preferably used.

This iodine-containing fluororubber has, for example, 0.001 to 10% by weight, preferably 0.01 to 5% by weight of iodine bonded to the end of the polymer chain, and vinylidene fluoride and at least one other compound that can be copolymerized with vinylidene fluoride. This is a fluororubber (see JP-A-52-40543) whose main composition is an elastic copolymer consisting of fluoroolefin and

Other fluorine-containing ethylenically unsaturated monomers that can be copolymerized with vinylidene fluoride to give elastic copolymers include hexafluoropropylene, pentafluoropropylene, trifluoroethylene, trifluorochloroethylene, and tetrafluoroethylene. Representative examples include fluoroethylene, vinyl fluoride, perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether).

A particularly desirable fluororubber is vinylidene fluoride/
They are a hexafluoropropylene dielastic copolymer and a vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene ternary elastic copolymer.

For an aqueous fluororubber dispersion, the fluororubber emulsion itself obtained by polymerizing the above monomers by emulsion polymerization is usually used, but fluororubber emulsions obtained by emulsion polymerization, suspension polymerization, bulk polymerization, etc. Rubber may be crushed or pulverized if necessary, and dispersed in water using a surfactant if necessary.

Aqueous dispersions of fluororubber generally have a molecular weight of 10 to 7
Those containing 0% by weight, preferably 30 to 60% by weight of fluororubber are used, but these concentrations can generally be adjusted by concentration or dilution.

Usually, in addition to the above-mentioned surfactants, pigments used as general paint compounding agents, acid acceptors, fillers, etc. commonly used in the processing of fluororubber can be added to these aqueous dispersions as appropriate.

The specific aminosilane compound used in the present invention, which binds an amine group to the molecular terminal shown in the general formula above, functions as a vulcanizing agent for fluororubber (this also improves the adhesion to the base material). It also appears to make a large contribution, and can be used safely even when compared to the aqueous medium Q.

Representative compounds include γ-aminopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, N-(trimethoxysilylpropyl)ethylenediamine, N-β-aminoethyl-γ- Examples include aminopropylmethyldimethoxysilane, γ-ureidopropyltriethoxysilane, β-aminoethyl-β-aminoethyl-γ-aminopropyltrimethoxysilane, and the like.

To prepare the water-based paint of the present invention, an aqueous dispersion of fluororubber [the above-mentioned pigments, acid acceptors, fillers, etc.] are blended according to a conventional method, and if necessary, a surfactant is further added. It's okay.

), to the resulting dispersion, add the aminosilane compound represented by the above general formula (if necessary, add the above pigment, acid acceptor,
Additives such as fillers may also be used.

) or by a conventional method (by thoroughly mixing them, a uniform fluororubber water-based paint can be obtained).

In addition, when adding the aminosilane compound of the general formula to the aqueous dispersion of the fluororubber, if it is added directly, the viscosity may increase and gelation may occur in some parts.

To prevent this, the aminosilane compound may be partially or completely hydrolyzed with water before addition.

The amount of the aminosilane compound added is usually 10% of the fluororubber.
The amount ranges from 1 to 30 parts by weight, preferably from 2 to 20 parts by weight per 0 parts by weight.

As the acid acceptor, those commonly used in the vulcanization of fluororubber can be similarly used, such as one or more divalent metal oxides or hydroxides.

Specific examples include oxides or hydroxides of magnesium, calcium, zinc, lead, and the like.

Further, as the filler, silica, clay, diatomaceous earth, talc, carbon, etc. are used.

The fluororubber water-based paint according to the present invention is applied or impregnated onto a base material by a conventional coating method (brushing, dipping, spraying, etc.) and cured for an appropriate period of time at a temperature between room temperature and 200°C. By doing so, a fluororubber coating film with excellent adhesion to the substrate can be obtained.

As described above, the water-based paint of the present invention has greatly improved adhesion to substrates compared to conventional water-based paints, has a better pot life than solvent-based paints, and is free from abnormalities such as stringing during spray painting. In addition to being easy to handle during construction, as it does not cause any untoward incidents, it also has the advantage that environmental measures such as ignition and pollution can be easily taken because no organic solvents are used.

The fluororubber water-based paint according to the present invention is mainly used as an anticorrosive or protective paint in the industrial fields mentioned above, and in addition, it can be effectively used as a sealing material, an adhesive, and as a conductive paint.

Hereinafter, the content of the present invention will be specifically explained using examples.

Parts indicate parts by weight. Examples 1 to 4 and Comparative Examples 1 to 3 (Coating film drawing test) Next (after uniformly mixing liquids A and B in a predetermined ratio, purifying with a 200-mesh wire mesh to obtain a water-based fluororubber Got the paint.

The aluminum plate was degreased by washing with acetone.

This degreased aluminum plate surface Q was spray coated with the above paint, and then dried at 50 to 70°C for 10 minutes.

Further, the same spray coating and drying steps were repeated three times in total to form a coating film with a thickness of 100 to 150 μm.

Subsequently, the coating was cured at 150° C. for 1.5 hours.

In order to examine the coating film characteristics of each test piece obtained, a drawing test was conducted according to the method of JIS K6894, and 5
Evaluation was performed using a stepwise method.

The results are shown in Table 1. For comparison, tests were conducted in the same manner as above using a polyamine compound instead of the aminosilane compound, and the results are shown in Table 1.

Examples 5 to 7 and Comparative Example 4 (Peeling test of coating film) A cured coating film of fluororubber was obtained on a predetermined substrate surface in the same manner as in Example 1.

Each of the obtained coating films was cut into a rectangular shape of 'h 10 mn (
Cut the base material to the extent that it will be scratched, and use a Shimadzu Autograph IS-500 to measure the edges at 50.0±2.5 at 24°C.
A 180 degree peel test was performed by pulling at a speed of mm/min.

The test results ※※ are shown in Table 2.

Example 8 (Coating film physical property test) A water-based paint was prepared in the same manner as in Example 1 except that the amount of aminosilane compound A-1100 was changed.

This was applied to an aluminum plate whose surface was coated with polytetrafluoroethylene using a spray gun, dried, and this process was repeated three times.
．． 5 hours), a cured coating film of approximately 100 μm of fluororubber was formed.

Thereafter, this coating film was peeled off from the substrate to obtain a fluororubber sheet.

Each sheet obtained was measured for 100% modulus, tensile strength, and elongation according to the method of JIS K6301.

The results are shown in Table 3. Example 9 and Comparative Example 5 (Pot life and spray coating test) The following liquids A and B were mixed at a predetermined ratio, and a fluororubber water-based paint was obtained in the same manner as in Example 1.

-1 Example 9: Fluorine rubber aqueous dispersion Example 9: Liquid A: Liquid B = 100:5 Comparative example 5: Liquid A: Liquid B = 100:22.2 The obtained fluororubber paint was applied to a 300 yd lid. The pot life was examined by placing the pot in a glass bottle and allowing it to stand at 24°C.

As a result, the solid content of the water-based paint of Example 9 gelled after 30 days of standing, making redispersion impossible, whereas the solvent-based paint of Comparative Example 5 gelled after 30 days of standing. After about 4 hours, a gradual increase in viscosity was observed, and after about 8 hours, the entire coating became gel-like and unusable as a paint.

In addition, the above-mentioned fluororubber paint was separately spray-painted on an aluminum plate under the following conditions: nozzle diameter, o, 8 mt.
n spray pressure, 3. OKt/crito As a result, in the case of the solvent-based Comparative Example 5, a stringing phenomenon appeared immediately after spraying started, but in the case of the water-based Example 9, there was no abnormality in the spray painting and a smooth coating film was obtained. It was done.

Claims (1)

[Claims] 1. In the aqueous dispersion of fluororubber, the general formula %) (3) [In the formula, R is -CH3 or -C2H5, R' is -CH
3. R” bar C3H6-1X is a single bond, (-C2H,N
H+, (-C-NH or (-C2H,i NHC
2H4NH+, y is 2 or 3. A fluororubber water-based paint containing an aminosilane compound represented by the following formula or a partial or complete hydrolyzate thereof. 2. The paint according to claim 1, which contains an aminosilane compound in an amount of 1 to 30 parts by weight per 100 parts by weight of fluororubber.