JPS6028458A - Coating composition - Google Patents

Abstract

PURPOSE:To obtain room temperature-curable titled composition free from gelling and coloring, with excellent long-term storage stability, by incorporating a tertiary amine in a hydroxyalkyl group-contg. fluorolefin copolymer solution. CONSTITUTION:The objective composition can be obtained by incorporating (A) an amount of solution per g of hydroxyalkyl group-contg. fluorolefin copolymer (pref. having 0.5-50mol% of hydroxyalkyl-vinylether-based structural unit) in it with (B) pref. 1mu-1m of a tertiary amine (pref. with a basicity pKa 8.0-11.5 and a boiling point 50-200 deg.C; e.g., triethylamine).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating composition having excellent storage stability and comprising a rhoolefin copolymer as a main component and a tertiary amine added thereto.

A fluoroolefin copolymer containing a hydroxyalkyl group is obtained, for example, by solution polymerization of a hydroxyalkyl vinyl ether and a fluoro-p-olefin, a fluoroalkyl vinyl ether, a fluoroalkyl vinyl ether, etc., and the resulting reaction solution (hereinafter referred to as the polymerization reaction solution) ) is used as a base for room-temperature curing paints, either as it is or diluted with aromatic hydrocarbons or paint thinners.

Paints based on Kakarufluoroolefin copolymers have excellent chemical resistance, weather resistance, stain resistance, and heat resistance, but they have poor storage stability and acid generation during storage, causing the pH of the solution to drop. decreases and turns into a gel.

As a result of our research, the present inventors found that this gelation is caused by the oxidative decomposition of the fluoroolefin monomer remaining in the polymerization reaction solution to generate acid, which attacks the hydroxyl groups in the copolymer and causes crosslinking. Gelation is thought to occur, and gelation varies depending on the molecular weight of the copolymer and the concentration of the solution.
It has been found that when H is 3 or less, it is raw, and when this polymerization reaction liquid is used as a paint base, it is desirable to maintain the pH at 4 or more.

Therefore, the present inventors attempted to prevent gelation by adding various basic substances to the polymerization reaction solution. First, basic inorganic compounds such as sodium tetraborate and sodium carbonate were added to the polymerization system and the polymerization reaction solution. When the acid was removed, it was possible to temporarily keep the polymerization reaction solution neutral, but acid was gradually generated and gelation occurred, resulting in a lack of long-term storage stability. The reason for this is thought to be that the basic inorganic compound hardly dissolves in the polymerization reaction solution.

Next, I tried adding basic organometallic compounds such as metal alcoholades and metal phenolates, but their basicity was too strong, causing decomposition and coloring of the copolymer, which could be used as a paint base. It wasn't.

Furthermore, when an amide compound or amine compound with good solubility was added to the polymerization reaction solution, the amide compound was unable to prevent gelation, while the primary and secondary amines caused coloring and were not able to prevent gelation much. However, it was surprisingly discovered that only tertiary amines have an excellent anti-gelling effect and cause almost no coloration, and the present invention was completed.

It is surprising that only tertiary amines can prevent gelation. This is because amine compounds are compounds used in crosslinking (gelation) through dehydrochlorination and dehydrofluorination reactions of fluorine-based copolymers.
This is because it is known that coloration occurs as a result of gelation, and it is true that such a reaction occurs when a primary amine and a secondary amine are added in the fluorocopolymerization containing a hydroxyalkyl group used in the present invention. This is because coloring occurs.

The tertiary amine used in the present invention is preferably a tertiary amine having a basic strength of, for example, pKa of 8.0 to 11.5, particularly 9 to 11. Sixth amines with a pKa of less than 8.0 tend to have a reduced gelation prevention effect; 11.
When the tertiary amine exceeds 5, deoxidation from the copolymer tends to occur easily, and coloring tends to become significant. Preferred third
Examples of amines include triethylamine, trin-
Examples include, but are not limited to, tetrapyramine, N-methylpyrrolidine, N-methylpiperidine, diethylpropylamine, N,N-dimethylbenzylamine, or a mixture of two or more thereof.

As the fluoroolefin copolymer containing a hydroxyalkyl group used in the present invention, those used in bases for room-temperature curing paints are employed. Such a copolymer is
As mentioned above, hydroxyalkyl vinyl ether and fluoroolefin, if necessary, alkyl vinyl ether,
Obtained by solution polymerization of monomers such as fluorotetraalkyl vinyl ether.

Examples of the hydroxyalkyl vinyl ether include hydroxybutyl vinyl ether, hydroxyethyl vinyl ether, hydroxypropyl vinyl ether,
- Preferably, the alkyl group has 3 to 10 carbon atoms, such as methyl-3-hydroxypropyl vinyl ether,
Examples of the fluoroolefins include chlorotrifluoroethylene and tetrafluoroethylene. As the alkyl vinyl ether, those in which the alkyl group has 1 to 10 carbon atoms are preferred, such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, inbutyl vinyl ether, and 2-chloroethyl vinyl ether. , and fluoroalkyl vinyl ethers include those in which the hydrogen atoms of the alkyl groups of the alkyl vinyl ethers are partially or completely substituted with fluorine atoms, and among these, for example, 2.2.
3.3-tetrafluoropropyl vinyl ether, 2.
2.3゜3,4.4.5.5-octafluoropentyl vinyl ether, 2.2.3.3.4.4.5.5.6
．． 6.7.7.8°8,9.9-hexadecafluorononyl vinyl ether and the like are preferred.

The fluoroolefin copolymer used as the main component of the coating composition of the present invention preferably contains 0.5 to 50 mol% of copolymer constitutional units based on hydroxyalkyl vinyl ether. Preferred fluoroolefin copolymers include, for example, those containing 50 mol% of hydroxyalkyl vinyl ether units, particularly 1 to 30 mol% of human tetraxyalkyl vinyl ethers, 40 to 60 mol% of fluorotetraolefins, and 20 mol% of alkyl vinyl ether units.
Preferably, it contains up to 50 mol%.

The solution polymerization method is used as the polymerization method, and the solvent is one or more copolymers of solvents such as acetic acid esters such as ethyl acetate and butyl acetate, and ketones such as methyl ethyl ketone and methyl isopropyl ketone. Any solvent can be used without particular restriction as long as it dissolves the polymer and does not interfere with the polymerization reaction. When using a mixed solvent, the mixing ratio may be changed as appropriate depending on the concentration of the copolymer to be obtained. As the polymerization initiator, for example, azo compounds such as azobisisobutyronitrile, and peroxides such as diisopropyl peroxydicarbonate and benzoyl peroxide are used. The usage of the polymerization initiator varies depending on its type, copolymerization reaction conditions, etc., but it is usually 0.005 to 1 mol%, preferably 0.1 to 0.0% based on the total molar amount of monomers.
．． It is 6 mol%.

The reaction temperature and reaction pressure are appropriately selected depending on the type of polymerization initiator and polymerization solvent, the molecular weight of the desired copolymer, etc., but the reaction temperature is usually 0 to 100°O, and the reaction pressure is is usually 100 to 9/cm2 or less, preferably 50kp/am2 or less.

A tertiary amine is added to the polymerization reaction solution of the fluoroolefin copolymer containing a hydroxyalkyl group obtained in this way.
1 microequivalent (hereinafter referred to as μeq/9) to 1
A range of milliequivalents (hereinafter referred to as meq/9) is preferred. When the amount of tertiary amine added is less than 1μ5q79, there is a tendency that the gelation prevention effect cannot be changed, and 1meq/9
If it exceeds 20%, the copolymer tends to be colored easily and is also economically unfavorable. A particularly preferred range is 10 μsq/9 to 500 μeq/9.

The coating composition of the present invention can be obtained by adding a tertiary amine to the polymerization reaction solution as described above, but it is also possible to add one or more of the above-mentioned solvents such as acetic esters and ketones to the polymerization reaction solution as appropriate. The copolymer concentration may be adjusted by The copolymer concentration is preferably 10 to 60% by weight, particularly 30 to 50% by weight.

The coating composition of the present invention is used as a base for a room-temperature curable coating, and is mixed with a pigment, a viscosity modifier, a leveling agent, a film-forming curing agent, a wetting agent, etc. to prepare a coating.

In order to cure the composition of the present invention at room temperature, for example, polyvalent isocyanates may be used.

When using polyvalent isocyanates, the added tertiary
Preferably, the amine has a boiling point in the range of 50 to 200°. If the boiling point is less than 50°0, foaming may occur in the coating film depending on the curing conditions, and whitening may occur in the coating film due to the g&humidity effect due to the latent heat of vaporization.

If the boiling point exceeds 20,000, the amine remains in the coating film for a long period of time, and the physical properties of the coating film tend to deteriorate due to moisture absorption of the amine.

Next, the coating composition of the present invention will be explained based on Examples.

Example 1 Content fl that was sufficiently replaced with nitrogen gas and maintained in a reduced pressure state
In a JR 1000 mj glass autoclave with a stirrer, 160 ml of sufficiently deoxygenated butyl acetate, 160 mA of S ethyl acetate, 130 mA of 2.2.3.3-tetrafluoropropyl vinyl ether (hereinafter referred to as 4IFVl)
p,4-hydroxybutyl vinyl ether (HD
vIc) and 1.69 g of azobisisobutyronitrile, and then chlorotrifluoroethylene (hereinafter referred to as O'rFE) 117 g. introduced, 70
The temperature was raised to °C. The temperature inside the autoclave is 70'
When O is reached, the pressure inside the autoclave is 4.7 kg.
/am2. Thereafter, the reaction was continued under stirring at the same temperature for 4 to 5 hours, and when the pressure decreased to 1.0 to 9/cm2, the autoclave was cooled to room temperature by water cooling, and the interior of the autoclave was replaced with nitrogen to remove unreacted monomers. was removed. The average polymerization rate of this copolymerization reaction is 160g
/1hrz monomer reaction rate was 86% by weight, and the resulting copolymer composition was 50% O'I'FE, 4'I
PVB+39%/l/% and HDVK i 1 mol%. The copolymer concentration of the obtained polymerization reaction solution was 47% by weight.Butyl acetate was added to the obtained polymerization reaction solution to adjust the copolymer concentration to 40% by weight, and then 100g of the reaction solution was added. Add 120% triethylamine to this
mg was added and thoroughly stirred. The amount of triethylamine added was 30 μeq/liter.

50 ml of the obtained coating composition of the present invention was placed in a 50 m4 sample tube, sealed, and placed in a constant temperature bath maintained at 40°0 to determine the storage condition (presence or absence of gelation) and presence or absence of coloring. When examined, it was found that it did not gel even after 6 months and only turned slightly yellow.

Examples 2 to 7 A copolymer having the composition shown in Table 1 was produced in the same manner as in Example 1, and the resulting polymerization reaction solution was adjusted to the copolymer concentration shown in the same table, and then triethylamine was added at 30 μeq/9. The composition of the present invention was obtained by adding the following.

When their storage condition and presence or absence of coloration were examined in the same manner as in Example 1, it was found that they did not gel even after 6 months and were only slightly colored pale yellow.

In Table 1, TFEiG; t is tetrafluoroethylene, EvIc is ethyl vinyl ether, and n-BVE is n-butyl vinyl ether. The composition of the present invention was obtained by adding the tertiary amine shown in Table 2 in the proportion shown in the table. In addition to examining the storage state and coloring state, a coating film was formed as follows and its state and coloring state were also examined.

The results are shown in Table 2.

To form a coating film, add hexamethylene diisocyanate trimer in an amount such that the incyanate groups correspond to the water groups in the copolymer, mix thoroughly, and apply it on an aluminum plate. This can be done by leaving it at room temperature for 3 to 5 days.

Comparative Example 1 A comparative composition was prepared in the same manner as in Example 8 except that triethylamine was not added, and the storage state, coloring state, coating film state, and coloring state of the composition were determined in the same manner as in Example 8. I looked into it.

The results are shown in Table 2.

Comparative Examples 2 to 5 Comparative compositions were prepared in the same manner as in Example 8, except that the basic substances shown in Table 2 were added in the proportions shown in the same table. The storage condition, coloring condition, paint film condition, and coloring condition were investigated. The results are shown in Table 2〇 Procedural amendment (voluntary) September 2, 1988 1 Indication of case 1988 Patent application No. 156556 2 Name of invention Paint composition 3 Relationship with the person making the amendment Patent applicant address New Hankyu Building, 1-12-39 Umeda, Kita-ku, Osaka Name (285) Daikin Industries, Ltd. Representative Yama 1) Representative Minoru 4 540 5 Subject of arrest (1) Specification Contents of amendment in column 6 of “Detailed Description of the Invention” (1) Change “3 to 10” on page 6, line 11 of the specification to “2 to 10”
and correct it.

(2) ``Correct HDVEJ to [nvr;J'' on page 11, line 7.

that's all QQ')-

Claims (1)

[Scope of Claims] 1. A coating composition comprising a fluoroolefin copolymer solution containing a hydroxyalkyl group as a main component, to which a 6th amine is added. 2. The composition according to claim 1, wherein the tertiary amine has a basic strength of pKa 8.0 to 11.5. 3 The fluoroolefin copolymer contains 0.5 to 5 copolymer constitutional units based on hydroxyalkyl vinyl ether.
A composition according to claim 1 containing 0 mol %. 4. The composition according to claim 1, wherein the tertiary amine is a fluoroolefin copolymer (19) and an additive of 1 micro to 1 mm. 5. The composition according to claim 1, wherein the tertiary amine has a boiling point of 50 to 200°0.