JPS58136662A - Coating composition - Google Patents

Abstract

PURPOSE:To provide a coating compsn. which has excellent applicability and gives a coating having good gloss, by dissolving a specified fluorocarbon polymer and a hardener in an org. solvent. CONSTITUTION:A coating compsn, is obtd. by dissolving a fluorocarbon polymer composed of a copolymer contg. a fluoroolefin, cyclohexyl vinyl ether, an alkyl vinyl ether and a hydroxyalkyl vinyl ether as essential constituents and a hardener in an org. solvent, said copolymer being composed of 40-60mol% of fluoroolefin, 5-45mol% of cyclohexyl vinyl ether, 5-45mol% of alkyl vinyl ether, 3-15mol% of hydroxyalkyl vinyl ether and 0-30mol% of other comonomer, said copolymer in an uncured state having an intrinsic viscosity of 0.05-0.1dl/g at 30 deg.C in tetrahydrofuran, and said hardener being a polyfunctional compd. reactive with hydroxyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating composition, and more specifically, to a coating composition in which a specific fluorine-containing copolymer and a curing agent are dissolved in an organic solvent. The present invention relates to a coating composition that provides an excellent coating film.

The present inventors have discovered that fluorine-containing copolymers containing units based on fluoroolefins, cyclohexyl vinyl ethers, and alkyl vinyl ethers and hydroxyalkyl vinyl ethers have excellent solubility in various organic solvents, weather resistance, It was discovered that it was extremely useful as a paint base, as it provided a wall film with good gloss and adhesion to the base material, and was hardenable.
The application is currently being filed as No. 89.

However, as a result of further investigation into the use of such fluorine-containing copolymers as paint bases, we found that the initial relatively high molecular weight fluorine-containing copolymers were not suitable for use as paint bases for spray painting. In this case, the solution concentration must be lowered due to viscosity, which results in a smaller coating film thickness per application, and when used as a top coat, the surface smoothness becomes poor, resulting in poor gloss of the coating film. I learned that there are some drawbacks, such as the fact that it becomes a nuisance.

As a result of extensive research based on recognition of the above problems, the present inventors have found that a specific fluorine-containing copolymer with a relatively low molecular weight having a specific intrinsic viscosity is used as a paint base, and a specific curing agent is used. It has been found that by doing so, such problems can be solved and a coating composition that provides a coating film with excellent workability and excellent gloss can be obtained.

Thus, the present invention has been completed based on the above findings, and provides an Ishigami 9 set IJk product in which a fluorine-containing polymer and a curing agent are dissolved in an organic solvent. A copolymer containing fluoroolefin, cyclohexyl vinyl ether, alkyl vinyl ether and hydroxyalkyl vinyl ether as essential components, fluoroolefin, cyclohexyl vinyl ether, alkyl vinyl in the copolymer:
The content of units based on hydroxyalkyl vinyl ethers and other monomers is 40-600-60 mol%, 5 mol%, 5-45 mol%, 3-15 mol% and 0-3 mol t4, respectively. The intrinsic viscosity determined in the cured state in tetrahydrofuran at 30° C. is n, 05
dA/2 or more 0.1 d17'? The present invention provides a novel coating composition characterized in that the temperature is 17°C and the curing agent is a polyfunctional compound that is reactive with hydroxyl groups.

In the present invention, the fluorine-containing polymer contains 40 to 600 to 60 mol%, 5 to 45 mol%, and 3 to 15 mol%, respectively, of fluoroolefin, cyclohexyl vinyl ether, alkyl vinyl ether, and hydroxyalkyl vinyl ether as essential constituents. %, preferably 45-555-55 mol% 50 mol% respectively
It is important that the content is from 10 to 350 to 35 mol% to 13 mol%.

Too low a fluoroolefin content is not only undesirable in terms of weather resistance, but also causes inconvenience in manufacturing. Also, those containing too high a fluoroolefin content are also difficult to manufacture. On the other hand, if the cyclohexyl vinyl ether content is too low, the hardness when formed into a coating film is undesirable, and if the alkyl vinyl ether content is too low, the flexibility is undesirable.

It is particularly important that the hardening copolymer contain hydroxyalkyl vinyl ether in the proportion within the above range from the viewpoint of improving curability without impairing various useful properties as a paint base. be. In other words, if the copolymer has a high content of hydroquine alkyl vinyl ether, the solubility of the copolymer changes and it becomes soluble only in certain substances such as alcohols, which limits its applicability as a base for m-dispersible paints. This is undesirable because it not only reduces the flexibility of the cured coating, but also reduces the gelation time (pot life) in the presence of a curing agent, significantly impairing the paint's workability. If the content is too low, the effect of improving curability will be lost, resulting in hardness,
This is undesirable because it increases the heating time, reduces the solvent resistance of the cured coating film, and reduces the 11111 staining resistance, and also causes disadvantages such as impairing the adhesion to the substrate and primer.

In the present invention, as the fluoroolefin, haloolefins, particularly chlorotrifluoroethylene or tetrafluoroethylene, are preferably employed. Further, as the alkyl vinyl ether, those containing a straight-chain twisted or branched alkyl group having 2 to 8 carbon atoms, particularly those in which the alkyl group has 2 to 4 carbon atoms, are preferably employed. Note that the fluoroolefins and alkyl vinyl ethers are not limited to being used alone, but may also be used in the form of a mixture of two or more types.

The above copolymers may contain units based on comonomers other than the above four essential constituents within a range not exceeding 30 molar units.

Examples of such comonomers include olefins such as ethylene, propylene, and imbutylene, haloolefins such as vinyl chloride and vinylidene chloride, unsaturated carboxylic acid esters such as methyl methacrylate, vinyl acetate, vinyl n-butyrate, and the like. Examples include vinyl carboxylates.

In the present invention, it is important that the intrinsic viscosity of the copolymer having the above composition measured in an uncured state in tetrahydrofuran at 30°C is 11.05 dZ/f or more and n or more and less than i tyy'. . If the viscosity is too low, the mechanical strength will decrease, and if the blade is too high, when applied as a solution type paint, there will be a tendency that the solution concentration will have to be lowered from the viewpoint of viscosity, especially in spray painting etc. In this case, the coating thickness per coat becomes small, which impairs the rollability, and when used as a top coat, the surface smoothness becomes poor, resulting in a coating with poor gloss, both of which are undesirable. For example (v] n47 dib/y
A copolymer with an intrinsic viscosity of less than [η) [1,1d6/f] will cause threading during spray painting if the polymer concentration in the paint exceeds 18%. In combination, even when the polymer concentration is 60% or more, a smooth spray-painted surface can be obtained without causing stringiness. Furthermore, the dry film thickness per spray coating without sagging is only 10 μm in the former case, while it reaches 50 μm or more in the latter case. Furthermore, the so-called wet-on-wet method involves applying a topcoat before the undercoat dries.
When painting, the former results in noticeable skin roughness on the surface of the paint film, while the latter provides a high gloss of 80% (60''-60° specular reflection) or more.

The above copolymers are produced by causing a copolymerization reaction by allowing a polymerization initiator, such as a polymerization initiator or ionizing radiation, to act on a monomer mixture in a predetermined proportion in the presence or absence of a polymerization medium. It can be manufactured by

Here, as the polymerization initiator, water-soluble or oil-soluble ones can be used as appropriate depending on the polymerization type or polymerization medium. Specifically, the water-soluble initiator is
A redox initiator consisting of a persulfate such as potassium persulfate, hydrogen peroxide, or a combination of these with a reducing agent such as sodium bisulfite or sodium thiosulfate, as well as small amounts of iron, ferrous salts, silver nitrate, etc. An inorganic initiator, such as a system in which dibasic acid peroxide, diglutaric acid peroxide, or monosuccinic acid peroxide coexists, or an organic initiator, such as dibasic acid oxide, azopisimptylamidine dihydrochloride, etc. , as oil-soluble initiators, t-butyl peroxyin butyrate, t
Examples include peroxy ester type peroxides such as -butyl peroxyacetate, dialkyl peroxy dicarbonates such as -inpropyl peroxin carbonate, benzoyl peroxide, and azobisine butyronitrile. The amount of the polymerization initiator used can be changed as appropriate depending on the type, copolymerization reaction conditions, etc., but it is usually 0.005 to 5% by weight, especially 0.05% by weight, based on the total amount of monopolymers to be copolymerized. ~05% by weight is adopted.

In the above copolymerization reaction, the reaction format is not particularly limited, and bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization, etc. can be adopted, but the stability of the polymerization reaction operation and the separation of the produced copolymer can be improved. For ease of emulsion polymerization in an aqueous medium, alcohols such as Ut-butanol, esters, saturated halogenated hydrocarbons containing one or more fluorine atoms, aromatic hydrocarbons such as xylene, etc. Solution polymerization using a solvent as a solvent is preferably employed. In addition, when carrying out a copolymerization reaction in an aqueous medium, it is preferable to add a basic buffer so that the pH value of the liquid during polymerization does not fall below 4, preferably 6. Addition of a basic substance is also effective in solution polymerization. Moreover, it goes without saying that the method of the present invention can be carried out by batchwise, semi-continuous, continuous, etc. operations.

In this copolymerization reaction, the copolymerization reaction temperature is -50°C.
The optimum value can be appropriately selected within the range of ~ +150°C depending on the polymerization initiation source, the type of polymerization medium, etc., but when the copolymerization reaction is carried out in an aqueous medium, the temperature is 0°C ~ +100°C, preferably 10°C. C. to about 90.degree. C. may be adopted. In addition, the reaction pressure can be selected as appropriate, but is usually 1 to 100 Ky/
cm2. In particular, it is desirable to adopt a value of about 2 to 50 to /α2.

In order to suppress the intrinsic viscosity of the resulting copolymer within the above range, it is preferable to carry out the copolymerization reaction in the presence of a suitable chain transfer agent using a reaction medium with a relatively large chain transfer constant.

In the present invention, it is important to use a polyfunctional compound having hydroxya contained as a curing site in the copolymer as the curing agent. Examples of such curing agents include heat-curing type curing agents such as melamine curing agents, urea resin curing agents, and polybasic acid curing agents, which are used in ordinary thermosetting acrylic paints.As melamine curing agents, Examples include butylated melamine, methylated melamine, epoxy-modified melamine, etc., and various degrees of modification from 0 to 6 can be used depending on the purpose, and the degree of self-condensation can also be selected as appropriate. Examples of urea resin include methylated urea,
Examples include butylated urea. Examples of the polybasic acid curing agent include long-chain aliphatic dicals, bonic acids, aromatic polyvalent carbon #IW or its anhydride, block polyvalent incyanates, etc. Useful. When using melamine or urea hardeners, curing can be accelerated by adding an acidic catalyst.

As the curing agent in the present invention, a room temperature curing type such as polyvalent incyanates can also be used. As polyvalent incyanates, non-yellowing diincyanates such as hexamethylene diincyanate and inphorone diincyanate, and adducts thereof are particularly useful. When curing at room temperature using incyanates,
It is also possible to accelerate curing by adding known catalysts such as dibutyltin dilaurate.

In the present invention, various solvents can be used as the organic solvent, including aromatic hydrocarbons such as xylene and toluene, alcohols such as n-butanol, esters such as butyl acetate, and ketones such as methyl in butyl ketone. In addition to glycol ethers such as ethylseronulp, etc., various commercially available thinners can also be used, and these can also be used by mixing them in various proportions. It is desirable to select such an organic solvent as appropriate, taking into account the condition of the object to be coated, the evaporation rate, the working environment, etc.

In preparing the coating composition of the present invention, it is possible to use various equipment commonly used for forming coatings, such as a ball mill, a paint shaker, a sand mill, a jet mill, a three-roll mill, a kneader, and the like. At this time, pigments, dispersion stabilizers,
It is also possible to add viscosity modifiers, leveling agents, antigelation agents, ultraviolet absorbers, and the like.

The coating composition of the present invention is used as a heat-curable so-called baking paint. In some cases, curing agents such as melamine, urea resins, polybasic acids or their anhydrides, and block polyvalent incyanates are also mixed at the same time during the above-mentioned preparation.
Used as a powder paint.

On the other hand, when used as a cold-curable coating material using non-blocking polyvalent incyanates, etc., the curing agent components are prepared separately and a two-component coating material is prepared. In this case, by adjusting the type and amount of incyanate and catalyst added, copolymer concentration, content of hydroxyalkyl vinyl ether-based units in the copolymer, etc.
The paint has a pot life of about 0 hours, cures at room temperature in several hours to several days, and provides a coating film with good physical properties.

The coating composition of the present invention has excellent workability, surface hardness,
Colored steel plates, colored aluminum plates, aluminum sash, which can provide coatings with excellent gloss, flexibility, and excellent solvent resistance, stain resistance, and weather resistance under mild conditions. It is useful not only as a baking paint for such things, but also as an air-drying paint that can be applied on-site.
The material of the base material is not limited to metals such as iron, aluminum, copper, or their alloys such as stainless steel and brass, but also inorganic materials such as glass, cement, concrete, PRP, polyethylene, polypropylene, and ethylene-vinyl acetate copolymer. It is also useful for coatings such as nylon, acrylic, polyester, and ethylene, and is particularly useful as a top coat for coated objects that have another base coat.

They are also used in specific applications such as aluminum pools, exterior colored glass, and cement roofs.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 A stainless steel autoclave with an internal volume of 21 mm (pressure resistance 2.5 K17 cm2) was charged with 1742 mm of t-butanol.
5ee-butanol 9869, cyclohexyl vinyl ether (c-HyVE) 117g, ethyl vinyl ether (EVE) 111y, hydroxybutyl vinyl ether (HBVE) 71.7F, potassium carbonate 6.
92 and azobisinbutyronitrile (AIBN)
Prepare 2.6 r and remove dissolved air by solidifying with liquid nitrogen and degassing. Thereafter, 360v of chlorotrifluoroethylene was introduced into the autoclave and the temperature was gradually raised. When the temperature inside the autoclave reached 65°C, the pressure was 4.5 Kg/1wr2. Then 9.
The reaction was continued under stirring for 0 hours, and the pressure was 02Kg/cm.
”, cool the autoclave with water to stop the reaction. After reaching room temperature, purge unreacted monomers,
Open the autoclave. The resulting polymer solution is poured into water to precipitate the polymer, which is then washed and dried to recover the polymer. Polymer yield is 5872;
The polymer concentration was 31.5%, the monomer reaction rate was 892 cm, and the average polymerization rate was 45.2 t/#-h.

Intrinsic viscosity of the obtained polymer (in THF, 30°C) ([
η]) is ΩD 9 dj/9, and 13 (! NMR composition analysis result, 0TFFi) c -HyVFi / EVE
/ HBVK molar ratio is 51. O/i 6.5
/23.0/9.5.

This copolymer 1002 was mixed with 40 tons of aromatic solvent (manufactured by Toei Sangyo: Nurubetsun+1so) and 20 tons of mineral spirit.
t, xylene 20t, and methyl in butyl ketone 201 (polymer concentration 50%), benzophenone ultraviolet absorber (Kyodo Yakuhin: Bio-Nup 130) 10f, melamine curing agent (Mitsui Toatsu: Cymel) 305) 6t and para-toluenesulfonic acid curing catalyst (Mitsui Toatsu: Catalyst +6000) Ω52
Add acrylic paint to the steel plate and stir evenly.
After setting for 5 minutes, the above clear paint was spray coated to a dry film thickness of 60 μm. After setting for an additional 10 minutes, baking hardening was performed at 150° C. for 20 minutes.

The obtained coating surface had a smooth and glossy appearance, and the gloss was 83% (60°-60° specular reflection: the same applies hereinafter). Also, 10crn steel balls with a diameter of 1.6y and a weight of 500t
The product was subjected to a DuPont impact test in which it was dropped from a height of 300 ft, but no abnormalities were observed in the coating film.

Comparative Example 1 Polymerization was carried out using the same recipe as in Example 1, using only t-butanol and 116Of as the polymerization solvent. Polymerization was carried out for 10 hours (pressure decreased to 0.2 Kg/(7)2),
[η] = 0.41 polymer to 5949 (yield 90
0chi) obtained. As a result of compositional analysis of the copolymer by 13ONMH, 0TFE/'c-HxvE/EVE/H
The molar ratio of BVFi is 51.5/17.0/22.
It was O,/9.5.

A paint having the same formulation as in Example 1 was prepared using this copolymer, but it was impossible to spray paint due to severe stringiness. Therefore, the amount of solvent was increased to adjust the polymer concentration to 15%, and spray painting was performed using this. As a result, the surface of the coating film was noticeably rough, and the resulting coating film had a gloss of only 30 degrees. Moreover, the average film thickness of the top coat was 12μ.

Example 2 Polymerization was carried out using the same recipe as in Example 1 except for 5ec-butanol and 1160F as the polymerization solvent. After 10 hours of polymerization, the pressure decreased to 0.9/crn2. [1:] = 11.06 polymer 562f (yield 85.2%) was obtained. The composition of the copolymer is CTFK/
c-HyVE/, FVE/HBVB%
The ratio was 51.8/16.9/252/8.9.

When a coating composition similar to that in Example 1 was prepared and sprayed, a smooth coating with an average thickness of 70 μm and a gloss of 85% with good spray coating properties was obtained.

Example 3 Polymerization was carried out using the same recipe as in Example 1, using t-butanol 500f and i-propertool 4002 as polymerization solvents. When polymerization is carried out for 10 hours, the pressure is 0.3 Kg.
/1yn2. [η]-〇〇8 polymer 5
752 (yield 87.1%) was obtained. The composition of the copolymer is 0
TFE/c-HyVE/EVEli/HB
VE molar ratio: 52.0/17.2/21.
It was 8/90.

When the formulation and coating were carried out in the same manner as in Example 1, the spray coating properties were good, and a smooth film with a gloss of 83% and an average thickness of 62 μm was obtained.
A coating film was obtained.

Examples 4 to 10 Using the copolymer obtained according to the formulation of Example 1, the coating composition shown in the table was mixed, and an aluminum plate (o, at, alodine +
1000 treatment) surface was spray coated once, and the coating condition, coating surface condition, and film thickness were observed.

Comparative Example 2 Polymerization was carried out using the same recipe as in Example 1, using t-butanol 2322.5ec-butanol 9282 as a polymerization solvent. When polymerization is carried out for 10 hours, the pressure becomes 0.2 K1
It decreased to 7cm2. [η]-〇, 20 polymer ~ 5
929 (yield 89.7) was obtained. The composition of the copolymer is 0
TFE/c-HyVE/EVE/HBVE
The molar ratio was 50.8/17.2/23.17a9.

A paint similar to that in Example 1 was prepared and spray painting was attempted, but it was impossible due to severe threading. Therefore, by diluting the paint with a solvent and adjusting it to a 30% polymer concentration, it became possible to spray paint without threading, but the cured paint film had rough skin and the gloss remained at 40-50%. Ta. Moreover, the average film thickness was 20μ.

Comparative Example 3 Using the same recipe as in Example 3, polymerization was carried out using 800 f of 1-propanol in 400 t of t-butanol as a polymerization solvent. After 1° hour, the pressure was 1.0 K.
Descend to 17 cm2 and add 5 of the polymer of [η]-〇〇4.
osr (yield 76%) was obtained. The composition of this copolymer is CT
FE /'c -HyVE /EVE / HBVFi
Molar ratio: 510/17.0/22.8/92
Met.

Using this copolymer, a coating material similar to that of Example 1 was prepared and sprayed, and good spray coating properties were obtained. The cured paint film was smooth and had a gloss of 85 degrees, but when we conducted an impact test, we found that cracks appeared in a radial pattern, and in some places the paint film was detached, which is necessary for practical purposes. It was found that the coating film strength could not be obtained.

Among agents: 1) Akira Ryo Hagiwara -

Claims (3)

[Claims] (1) In a coating composition formed by dissolving a fluorine-containing polymer and a curing agent in an organic solvent, the fluorine-containing polymer contains fluoroolefins, cyclohexyl vinyl ethers, alkyl vinyl ethers, and hydroxyalkyl vinyl ethers as essential components. A copolymer in which the content of units based on fluoroolefins, cyclohexyl vinyl ethers, alkyl vinyl ethers, hydroxyalkyl vinyl ethers and other copolymers is 40 to 600 to 60 mol% and 5 mol%, respectively. , 5~
45 mol%, 3 to 15 mol%, and 0 to 30 mol%, and the intrinsic viscosity measured in an uncured state in tetrahydrofuran at 30°C is 0.054179 or more. fCL
A coating composition characterized in that the A/F is untreated and the curing agent is a polyfunctional compound that is reactive with hydroxyl groups. (2) The coating composition according to claim 1, wherein the curing agent is used in an amount of 1 to 40 parts by weight per 100 parts by weight of the fluorine-containing value. , (3) The coating composition according to claim 1, wherein the fluoroolefin is tetrafluoroethylene t or chlorotrifluoroethylene.