JPH0832847B2 - Paint composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field] The present invention relates to a coating composition.

[Prior art] Shown in JP-B-55-44083 or JP-B-60-21686 as a paint resin that provides a coating film with extremely excellent weather resistance as compared with paint properties such as room temperature curability and general-purpose paints. Known fluororesins are known. The coating material using the fluororesin disclosed in these publications is, for example, as a solvent type coating material, for example, Japanese Patent Publications 61-41259, 61-41260, 61-412.
It is used as a heavy anticorrosion top coat as shown in 61 or the like, or as a top coat on a cement-based substrate as shown in JP-A-59-4473, and its weather resistance is It has become known that it is excellent.

However, since the fluororesin is supplied as a paint varnish using a so-called good solvent such as xylene as a thinner, a paint produced based on the varnish is used as a primer for rust prevention of synthetic oils, synthetic resin modified rust prevention or the like. When it is directly applied to a coating such as a modified synthetic resin mixed paint, phthalate resin enamel, or acrylic resin-based topcoat, there are drawbacks such as tingling and poor adhesion.

[Problems to be Solved by the Invention] The present invention is a primer for oil-based rust preventives, synthetic resin-modified rust preventives, etc., or a synthetic resin compounding paint, phthalic acid resin enamel, acrylic resin-based topcoat which is weather-deteriorated due to aging. It is intended to provide a coating composition having good adhesion without causing streaks when applied to an old coating film such as.

[Means for Solving the Problems] The present invention has been made to solve the above problems, and has a fluorine content of 10% by weight or more based on the fluoroolefin unit, Provided is a coating composition comprising a mineral spirit-soluble fluorocopolymer having a copolymerization ratio of 30 to 70 mol% and an intrinsic viscosity of 0.05 to 2.0 dl / g measured in tetrahydrofuran, and mineral spirit. To do.

In the coating composition of the present invention, the mineral spirit-soluble fluorine-containing copolymer has a fluorine content based on the fluoroolefin unit of 10% by weight or more, and the copolymerization ratio of the fluoroolefin unit is 30 to 70 mol%. , An intrinsic viscosity measured in tetrahydrofuran of 0.05 to 2.0 dl /
It is g. Fluorine content based on fluoro-olefin is 1
If it is less than 0% by weight, the weather resistance becomes insufficient and the advantage as a weather resistant coating film or a repair coating film is diminished. Further, if the intrinsic viscosity measured in tetrahydrofuran is outside the above range, a tough coating film cannot be obtained, or the coating operation becomes difficult, which is not preferable. Further, such a fluorine-containing copolymer has a fluorine content based on a fluoroolefin unit.
Even if it is 10% by weight or more, a fluorine-containing polymer insoluble in mineral spirits such as polytetrafluoroethylene, polychlorotrifluoroethylene, and tetrafluoroethylene-hexafluoropropylene copolymer is not adopted. A copolymer of fluoroolefin and vinyl ether is preferably used because of its solubility in mineral spirits. Examples of such fluoroolefins include tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride, hexafluoropropylene and the like, but tetrafluoroethylene and chlorotrifluoroethylene are particularly preferably adopted. Examples of vinyl ethers include alkyl vinyl ethers containing a linear, branched, or cyclic alkyl group having about 2 to 8 carbon atoms. Further, such vinyl ether may include fluoroalkyl vinyl ether in which a part or all of hydrogen bonded to carbon is substituted with fluorine.
The copolymerization ratio of fluoroolefin and vinyl ether is
Fluoroolefin 30-70 mol%, especially 40-60 mol%,
The vinyl ether content is preferably 70 to 30 mol%, particularly preferably 60 to 40 mol%. If the amount of the fluoroolefin is too large, the solubility in mineral spirits will be insufficient, and if it is too small, sufficient weather resistance will not be obtained. Also, 30 to 95 mol% of vinyl ether, especially
It is preferable that 40 to 80 mol% is a cyclic alkyl vinyl ether. When the amount of the cyclic alkyl vinyl ether is too small, when the hydroxyl group or carboxylic acid group described below is introduced into the fluorocopolymer, the solubility in mineral spirits becomes insufficient, and the fluorocopolymer as a coating composition. The content becomes too low to make it difficult to apply to thick film coating. On the other hand, if the amount of cyclic alkyl vinyl ether is too large, the adhesion to the primer or the deteriorated coating film is lowered, or the flexibility of the formed coating film is lowered, which is not preferable.

Such a mineral spirit-soluble fluorine-containing copolymer is subjected to a copolymerization reaction by causing a polymerization initiation source such as a polymerization initiator or ionizing radiation to act on a monomer mixture in a predetermined ratio in the presence or absence of a polymerization medium. It can be manufactured by urging.

In addition, it is preferable that the fluorine-containing copolymer has a hydroxyl group or a carboxylic acid group, from the viewpoint of excellent adhesion to a primer or a deteriorated coating film. The introduction of such a hydroxyl group or a carboxylic acid group is carried out by copolymerizing a hydroxyalkyl vinyl ether or the like in the production of a fluorine-containing copolymer, or by reacting a hydroxyl group-containing fluorine-containing copolymer with a dibasic acid anhydride. Can be carried out by a method such as converting at least a part of the above into a carboxylic acid group-containing group. The content of such hydroxyl group and carboxylic acid group is the hydroxyl value (hereinafter referred to as OHV)
And the sum of the acid values (hereinafter referred to as AV) is preferably 30 mgKOH / g or less. When the sum of OHV and AV is more than 30 mgKOH / g, the solubility in mineral spirits is deteriorated, thick film coating becomes difficult, and the moisture resistance and weather resistance of the coating film are deteriorated, which is not preferable. Particularly preferably, the sum of OHV and AV is 2
It is 0 mgKOH / g or less.

The coating composition of the present invention contains the mineral spirit-soluble fluorine-containing copolymer and the mineral liquid described above. It is most preferable that the total amount of the fluorine-containing copolymer contained in such a composition is dissolved in mineral spirits, but there may be some insoluble portion. The amount of mineral spirits is appropriately selected depending on the type of the fluorocopolymer, the coating method, etc., but it is preferable to use at least an amount that can dissolve the total amount of the fluorocopolymer in the composition.

The coating composition of the present invention is used as a one-component air-drying coating, as a top coat or repair of a chemical plant to which a primer has been applied, an iron structure, and the like, and a chemical planft having a deteriorated coating film that has been applied in the past It is preferably used for repairing steel structures and buildings. Such a paint may be a clear paint containing no pigment,
It may also contain pigments or dyes such as titanium oxide. Further, the composition part of the present invention may contain other additives such as an ultraviolet absorber.

In addition, the coating composition of the present invention contains CAB (cellulose acetate butyrate) in order to improve the drying property of the coating film.
Alternatively, NC (nitrocellulose) or the like may be added, and in order to improve the gloss and hardness of the coating film or the workability of the coating, a polymer made of acrylic acid or its ester, or a coating resin such as polyester is included. You can leave.

[Examples] The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples and Comparative Examples.

Manufacture of fluorinated copolymer 110 g of t-butanol in an autoclave with a stirrer made of stainless steel with an internal volume of 200 cc and cyclohexyl vinyl ether (CHVE), ethyl vinyl ether (EVE), hydroxybutyl vinyl ether (HBV) in the proportions shown in Table 1.
W), 2 g of potassium carbonate and 0.1 g of azobisisobutyronitrile were charged and the dissolved air was removed by solidification and deaeration with liquid nitrogen. Then, chlorotrifluoroethylene (CTFE) in the proportion shown in Table 1 was introduced into the autoclave, and the temperature was gradually raised. After the temperature inside the autoclave reached 65 ° C, after continuing the reaction under stirring for 7.2 hours,
The autoclave was cooled with water to stop the reaction. After reaching room temperature, unreacted monomers were purged and the autoclave was opened. The obtained polymer solution was poured into water to precipitate the polymer, which was then washed and dried to collect the polymer. Charge the recovered polymer into a 200cc four-necked flask with a stirrer,
After xylene was added and dissolved, succinic anhydride was added. After further adding triethylbenzylammonium chloride, the temperature of the flask was gradually raised. After the solution in the flask reached 110 ° C., the temperature was maintained and the reaction was continued for 2 hours to obtain a polymer having a carboxylic acid group.

Intrinsic viscosity of the obtained polymer (in tetrahydrofuran,
30 ° C) ([η]), OHV and AV are shown in Table 1.

Examples 1 to 5 and Comparative Example 1 The fluorine-containing copolymers shown in Table 1 were used to prepare the compositions shown in Table 2. For a composition having good solubility, it was applied on a chromate-treated aluminum plate so as to have a dry film thickness of 20 to 30 μm, and after dried, adhesion was evaluated (by a goose eye peel test). . The results are shown in Table 2. The fluorinated copolymer 6 of Comparative Example 1 is a fluorinated copolymer having tetrafluoroethylene / hexafluoropropylene = 92/8 mol%.

[Effects of the Invention] The composition of the present invention gives a coating film having good adhesion and excellent weather resistance without causing tingling when coating on a primer or repair coating on an old coating film. Has the effect.

Claims (2)

[Claims] 1. The content of fluorine based on fluoroolefin units is 10% by weight or more, the copolymerization ratio of fluoroolefin units is 30 to 70 mol%, and the intrinsic viscosity measured in tetrahydrofuran is 0.05 to 2.0. A coating composition comprising a mineral spirit soluble fluorine-containing copolymer of dl / g and mineral spirits. 2. The coating composition according to claim 1, wherein the mineral spirit-soluble fluorine-containing copolymer is a copolymer of fluoroolefin and vinyl ether.