JPS5853672B2 - Fluoro rubber water-based paint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluororubber water-based paint, and more specifically, by blending a fluororubber with a specific aminosilane compound and a specific amine compound, sufficient adhesion to the substrate can be achieved. This invention relates to a fluororubber water-based paint that has significantly improved properties of the coating film, especially the tensile strength of the coating film, while maintaining the same properties.

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, water-based fluororubber paints using polyamine as a vulcanizing agent and solvent-based fluororubber paints using aminosilane as a vulcanizing agent are well known. Among the aminosilane compounds used in rubber paints, only the specific aminosilane compounds that bind amine groups to the molecular terminals produce good water-based fluororubber paints without causing gelation, and are suitable for pretreatment and adhesives. It is possible to obtain a coating film with sufficient adhesion to the substrate without the need for coating, and surprisingly, compared to the solvent-based fluororubber coatings mentioned above, the pot life is significantly improved, and it is also easy to use when spray painting. The fact that coating can be applied extremely advantageously without causing stringiness even in the case of a high fluoro rubber concentration, and furthermore, the technical effects described above can be achieved by adding water (partially or completely) in advance. A completely new finding has been obtained that more desirable results can be achieved when using the above-mentioned decomposed specific aminosilane compound (see Japanese Patent Application No. 103813/1983).

Based on the above findings, the present inventors continued their research and discovered that the aminosilane compound and a specific amine compound having at least one terminal amino group directly bonded to an aliphatic hydrocarbon group It is said that the fluororubber paint obtained by using fluorocarbon rubber in combination maintains sufficient adhesion to the base material, while significantly improving the properties of the paint film, especially the tensile strength of the paint film.
In other words, the present invention was completed based on the discovery of a completely unexpected effect in that it is possible to achieve a tensile strength of a coating film that cannot be obtained when each of the aminosilane compound and amine compound is used alone.

That is, the gist of the present invention is that (a) General formula: % formula %) (3) [In the formula, R is -CH3 or -C2H5, R' is -CH
3, R' is -C3H6-1X is a single bond, -eC2H4N
H)-1(-C-NH+ or +c2H, -NH-C2
H, -NH-), y-2 or 3.

] or a partial or complete hydrolyzate thereof; and (b) an amine compound having at least one terminal amino group directly bonded to an aliphatic hydrocarbon group. .

However, in the present invention, when the aminosilane compound used in the solvent-based fluororubber paint is used in the water-based fluororubber paint, not all the aminosilane compounds give a good fluororubber paint; Although certain aminosilane compounds have the disadvantage of causing the paint to gel, when a specific aminosilane compound that binds an amine group to the molecular end is used, a good fluororubber water-based paint can be obtained without causing the above-mentioned gelation defect. In addition, the water-based paint of the present invention has a pot life (even if it is difficult, solvent-based fluororubber paints usually gel at 25°C for 10 hours and become unusable). It is stable over a long period of 2 weeks to 1 month and is easy to handle during painting.

Furthermore, in spray painting, if the fluororubber concentration is 20% by weight or more with the solvent-based fluororubber paint, stringing will generally occur, making it difficult to withstand long-term use.
Therefore, it has the disadvantage that the fluororubber concentration must be kept at 20% by weight or less, or 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.

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 ethylenic compound copolymerizable with vinylidene fluoride. Examples include elastic copolymers with saturated monomers.

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

This iodine-containing fluororubber has, for example, 0.001 to 10% by weight, preferably o, oi to 5% by weight of iodine bonded to the end of the polymer chain, and vinylitine fluoride and at least one type of iodine that can be copolymerized therewith. It is a fluororubber whose main composition is an elastic copolymer composed of other fluoroolefins (see Japanese Patent Laid-Open No. 40543/1983).

Other fluorine-containing ethylenically unsaturated monomers that are copolymerized with vinylidene fluoride to give elastic copolymers include hexafluoropropylene, pentafluoropropylene, trifluoroethylene, trifluorochloroethylene, and tetrafluoroethylene. Typical examples include ethylene, 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-mentioned monomers by emulsion polymerization is usually used, but it can also be obtained by emulsion polymerization, suspension polymerization, bulk polymerization, etc. If necessary, fluororubber may be crushed or pulverized and dispersed in water using a surfactant if necessary.

The aqueous dispersion of fluororubber is generally 10~
Those containing 70% 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 and fillers commonly used in the processing of the fluororubber can be appropriately added to these aqueous dispersions.

The specific aminosilane compound used in the present invention, which has an amide 7 group attached to the molecular terminal shown in the above general formula, not only functions as a vulcanizing agent for fluororubber, but also greatly improves adhesiveness with the base material. It is believed to contribute to the oxidative stress and can be safely used in aqueous media.

Typical examples include γ-aminopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, N-(1-rimethoxysilylprobyl)ethylenediamine, N-β-amino Ethyl-γ-aminopropylmethyldimethoxysilane, γ
-ureidopropyltriethoxysilane, β-aminoethyl-β-aminoethyl-γ-aminopropyltrimethoxysilane, and the like.

Further, the specific amine compound functions as a vulcanizing agent for fluororubber, and representative examples include ethylamine, propylamine, butylamine, benzylamine, allylamine, n-amylamine,
Monoamines such as ethanolamine, ethylenediamine, trimethylenediamine, tetramethylenediamine,
Hexamethylenediamine, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5
・5] Diamines such as undecane (hereinafter referred to as ■-11), polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine, among others, having two or more terminal amino groups Amine compounds are preferred, and the above V-11 is particularly preferred.

In order to prepare the water-based paint of the present invention, it is usually necessary to mix the above-mentioned pigments, acid acceptors, fillers, etc. into an aqueous dispersion of fluororubber according to a conventional method (in addition, a surfactant may be added to the water-based dispersion of fluororubber). You can.

) and the resulting dispersion (additives such as the pigment, acid acceptor, filler, etc. may be used as necessary) by adding an aminosilane compound represented by the above general formula.

) 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 some gelation may occur.

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

The amount of the aminosilane compound and amine compound added is usually 0.5 to 30 parts by weight per 100 parts by weight of fluororubber.
Preferably it is in the range of 1 to 20 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, etc.

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 of room temperature to 200°C. By doing so, a fluororubber coating film with excellent adhesion to the substrate and significantly improved tensile strength can be obtained.

As described above, the water-based paint of the present invention significantly improves the properties of the paint film, especially the tensile strength of the paint film, while maintaining sufficient adhesion to the substrate, and has a longer pot life than solvent-based paints. It is said to be easy to handle during construction, as it has good properties and does not cause abnormal situations such as stringing during spray painting, and because it does not use organic solvents, environmental measures such as ignition and pollution are easy to deal with. It also has advantages.

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 with reference to Examples.

However, parts indicate parts by weight. Examples 1 to 4 and Comparative Examples 1 to 15 (Physical property test of coating film) After uniformly mixing Solution B and/or Solution C with Solution A shown below so that aminosilane and/or amine are in a predetermined ratio. , Sawabetsu purification was carried out using a 200-mesh wire mesh to obtain a fluororubber water-based paint.

The resulting paint was applied to an aluminum plate whose surface was coated with polytetrafluoroethylene using a spray gun Q.
Dry, repeat this process 3 times, then cure (1
(at 50° C. for 0.5 hours) to form a cured coating film of about 150 μθ noft comb.

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

The tensile strength of each sheet obtained was measured according to the method of JIS K6301.

The results are shown in Table 1.

In addition, Example 1 using completely hydrolyzed A-iioo
In Examples 2 to 3, no gelation was observed in the paints.
4 (Although gelation occurred slightly in this case, there was no effect on the painting process.

The same procedure as in Example 1 was used except that A-1125 was used instead of A-1100 as an aminosilane that does not bond an amino group to the end of the molecule. Met.

Examples 5 to 9 and Comparative Examples 16 to 17 (Coating film physical properties and peeling test) Other than changing the amounts of aminosilane and amine used,
The test was conducted in the same manner as in Example 1.

JISK6301 for each fluororubber seam MC obtained.
The tensile strength was measured according to Method Q.

On the other hand, a fluororubber paint prepared in the same manner as in Example 1 was spray-painted on an iron plate surface that had been previously degreased by washing with acetone, 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 0.5 hour.

The coating film of each test piece obtained was cut into strips with a width of 10 mm to the extent that the base material was scratched, and the edges were heated at 24°C (50.0 ± 2, 5
A 180 degree peel test was performed by pulling at a speed of vrrn/min.

The test results are shown in Table 2. Example 10 and Comparative Example 18 (Pot life and spray coating test) The following solutions A, B and C were mixed so that A-1100 and ■-11 were each 0.005 mol per 100 parts of fluororubber. The mixture was mixed in the same manner as in Example 1 to obtain a fluororubber water-based paint.

A liquid Example lO: Fluororubber aqueous dispersion (Fluororubber content 60% by weight, Contains nonionic H8208.

) ...166 parts magnesium oxide ...
・・・・・・・・・・・・・・・・・・ Three parts of the obtained fluororubber paint were placed in a 300 TLl glass bottle with a lid, allowed to stand at 24°C, and the pot life was examined.

As a result, the solid content of the water-based paint of Example 10 gelled after 30 days of standing, making redispersion impossible, whereas the solvent-based paint of Comparative Example 18 gelled after 30 days of standing. After about 4 hours, a gradual increase in viscosity was observed, and after about 10 hours, the entire coating became gel-like and could no longer be used as a paint.

In addition, the above-mentioned fluororubber paint was spray-painted on an aluminum plate under the following conditions: Nozzle diameter, 0.8 mm; Spray pressure, 3.0 g/m. As a result, a solvent-based comparative example In the case of Example 18, a stringing phenomenon appeared immediately after the start of spraying, but in the case of the aqueous type Example 10, a smooth coating film was obtained without any abnormality.

Claims (1)

[Claims] 1. In an aqueous dispersion of fluororubber, (a)
General formula: %Formula%() (3) [In the formula, R is -CH3 or -C2H5, y is -CH3
, K' is -C3H6-1X is a single bond, +C2H,NH-
)-1 C-NH+ or (-C2H+ NHC2H
4NH+, y is 2 or 3. ] or a partial or complete hydrolyzate thereof; and (b) an amine compound having at least one terminal amine group directly bonded to an aliphatic hydrocarbon group. Rubber water-based paint. 2. The fluororubber water-based paint according to item 1, wherein the amino compound has at least two terminal amino groups directly bonded to an aliphatic hydrocarbon group. 3. The fluororubber water-based paint according to item 1 or 2 above, wherein the aminosilane compound and the amine compound are blended in a ratio of 0.5 to 30 parts by weight per 100 parts by weight of fluororubber. 4. The fluororubber water-based paint according to any one of Items 1 to 3 above, wherein the ratio of the aminosilane compound to the amine compound is 1:99 to 80:20 in molar ratio.