JPH0832848B2 - Fluororesin coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a fluorine-containing copolymer composition.

[Prior Art] Conventionally, fluororesin paints containing a solvent-soluble fluorine-containing copolymer as a main component have remarkably excellent weather resistance as compared with other general-purpose paints, and therefore metal, synthetic resin, fiber, glass, Widely used in various fields such as cement. A coating film based on a fluororesin paint has excellent weather resistance and is extremely less deteriorated by ultraviolet rays, etc., but when a clear coating film is used, it transmits ultraviolet rays, which causes deterioration of the base material. there were.

In order to solve this problem, a method of adding an ultraviolet absorber to the fluororesin paint has been implemented. Further, a composition containing a special ultraviolet absorber for the purpose of reducing the amount of loss of the ultraviolet absorber produced during baking of the coating film is also found in JP-A-60-36365. Further, a fluorine-containing copolymer having a group capable of absorbing ultraviolet rays is also found in JP-A-49-13229.

[Problems to be Solved by the Invention] A conventional fluororesin coating material containing a special ultraviolet absorber is
Part of the ultraviolet absorber is distilled out as the solvent evaporates during drying, and 100% of the added ultraviolet absorber is not utilized.
Further, there is a problem that unreacted ultraviolet absorber may bleed out.

Further, the fluorine-containing copolymer having an ultraviolet absorbing group is
There are problems that the soluble solvent is limited, for example, it is insoluble in a non-polar solvent, and the gloss of the coating film is difficult to appear.

[Means for Solving the Problems] The present invention has been made to solve the above problems, and is a fluororesin coating composition containing the following (a) and (b).

(A) Fluorine content based on fluoroolefin is 10
% By weight or more, having 30 to 70 mol% of polymer units based on alkyl vinyl ether or alkyl vinyl ester with respect to all polymer units, and having a polymer unit containing a group having an ultraviolet absorbing ability to 0.5 to all polymer units. It has 50 mol% and the intrinsic viscosity measured at 30 ° C. in tetrahydrofuran is 0.05 to
Fluorine-containing copolymer having a content of 2.0 dl / g (b) Curing agent The composition of the present invention has a fluorine content of 10% by weight or more based on a fluoroolefin and contains all polymerized units based on an alkyl vinyl ether or an alkyl vinyl ester. 30 to 70 mol% of the polymerized units, and 0.5 to 50 mol% of polymerized units containing a group having an ultraviolet absorbing ability (hereinafter referred to as UVAC) to all polymerized units in tetrahydrofuran. The intrinsic viscosity measured at 30 ° C is 0.05 to 2.
It contains a fluorine-containing copolymer of 0 dl / g and a curing agent. Examples of the fluoroolefin in the fluorine-containing copolymer include vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, pentafluoropropylene, hexafluoropropylene and the like. In particular, fluoroolefins having about 2 to 4 carbon atoms are preferable. As the alkyl vinyl ether or alkyl vinyl ester, a vinyl ether or vinyl ester having an alkyl group having about 1 to 15 carbon atoms is adopted. Such an alkyl group is
It may be a straight-chain type, a branched type, or an alicyclic type. Examples of such alkyl vinyl ethers include ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether, hexyl vinyl ether, cyclohexyl vinyl ether and octyl vinyl ether. Examples of the alkyl vinyl ester include ethyl vinyl ester, n-butyl vinyl ester, t-butyl vinyl ester, hexyl vinyl ester, octyl vinyl ester and decyl vinyl ester. Although various types of UVAC can be adopted, those having a basic structure of benzophenone type, benzotriazole type, or phenyl salicylate type are preferable because they are easy to manufacture and have excellent ultraviolet absorption. Here, the benzophenone type What is benzotriazole Or What is phenyl salicylate system? It has a basic structure of Such UVAC may be contained in the main chain of the fluorine-containing copolymer, but it is practically difficult to introduce UVAC into the main chain, and normally, UVAC is contained in the side chain.
Will be introduced. As a method for introducing such a UVAC, a vinyl-based monomer having a reactive group such as an epoxy group, a hydroxyl group, or an active hydrogen-containing group such as a carboxylic acid group is reacted with a reactive ultraviolet absorber, or a linking agent. A vinyl-based monomer having UVAC that is bound with an ultraviolet absorber using
A method of copolymerizing with a fluoroolefin and an alkyl vinyl ether or an alkyl vinyl ester, a fluorine-containing copolymer having a reactive group such as an active hydrogen-containing group such as an epoxy group, a hydroxyl group, and a carboxylic acid group, and a reactive ultraviolet absorber. There is a method of reacting, or a method of binding an ultraviolet absorber with a linking agent. Here, the linking agent is a polyfunctional compound having a group that reacts with both the reactive group of the vinyl monomer or the fluorine-containing copolymer and the reactive group of the ultraviolet absorber. For example, when the vinyl monomer or the fluorine-containing copolymer has a hydroxyl group, and the ultraviolet absorber has a hydroxyl group, it is difficult to directly react them, but a compound such as diisocyanate or polyvalent carboxylic acid is used. Both can be easily bound by reacting. The linking agent is a compound having the same action as diisocyanate, polycarboxylic acid and the like in this case.

Examples of reactive ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4- (2-hydroxyethoxy) benzophenone, and 2-hydroxy-4-.
(2-hydroxypropoxy) benzophenone, 2-
(2'-hydroxy-3 ', 5'-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl)
-5-chlorobenzotriazole, 4-carboxylic phenyl salicylate, 2-hydroxy-4- (2 '
-Succinate ethyl) benzophenone, 2- (2'-
Hydroxy-3'-aminomethyl) benzotriazole and the like are exemplified.

In the present invention, the fluorine-containing copolymer has a fluorine content based on fluoroolefin of 10% by weight or more. If the fluorine content is too low, good weather resistance cannot be achieved, which is not preferable. Further, polymerized units based on alkyl vinyl ether or alkyl vinyl ester are contained in an amount of 30 to 70 mol% based on all polymerized units. When the amount of the polymerized units based on the alkyl vinyl ether or alkyl vinyl ester is less than the above range, the solubility in a non-polar solvent becomes extremely low, and gloss when formed into a coating film is not obtained, which is not preferable. On the other hand, if the amount is too large, the weather resistance decreases, which is not preferable. The amount of UVAC is appropriately determined according to the purpose, but normally, a unit containing UVAC-containing polymerized units in an amount of 0.5 to 50 mol% based on all polymerized units is adopted. UVAC
When the amount of is small, a sufficient ultraviolet ray shielding effect cannot be achieved. On the other hand, if the amount is too large, the solubility in a solvent is lowered and the physical properties of the coating film are lowered, which is not preferable. When UVAC is introduced into the reactive groups of the fluorine-containing copolymer, UVAC may be introduced into all of the reactive groups when the reactive group is the same as the curing reaction site described later. But,
In order to secure the curability of the fluorinated copolymer, it is preferable to leave the reactive group, and the remaining amount is 50% of all the reactive groups.
The above is preferable.

In the present invention, the fluorinated copolymer may be a copolymer of a copolymerizable monomer in addition to the above three kinds of components. Examples of the copolymerizable monomer include allyl compounds, acryloyl compounds, methacryloyl compounds, olefins, and fluorine-containing vinyl compounds. Further, the fluorinated copolymer preferably has a curing reactive site.

Examples of the curing reactive site include an active hydrogen-containing group such as a hydroxyl group, a carboxylic acid group, an acid amide group, an amino group and a mercapto group, an epoxy group, an unsaturated group, an active halogen-containing group such as iodine and bromine, which can be hydrolyzed. Examples thereof include a silyl group. Above all, an active hydrogen-containing group or an epoxy group is preferably adopted because it has excellent reactivity with a curing agent described later.

Examples of the method for introducing the curing reactive site include copolymerizing a monomer having a curing reactive site, converting a part of the fluorocopolymer into the curing reactive site, and curing reactive site in the fluorocopolymer. Examples thereof include a method of reacting a compound having a group or providing a curing reactive site.
Here, as the monomer having a curing reactive site, hydroxyalkyl vinyl ether, hydroxyalkyl allyl ether, hydroxyalkyl vinyl ester,
Examples thereof include hydroxyalkyl allyl ester, glycidyl vinyl ether, glycidyl allyl ether, aminoalkyl vinyl ether, aminoalkyl allyl ether, aminoalkyl vinyl ester, aminoalkyl allyl ether, acrylic acid, methacrylic acid and allyl vinyl ether. As a method of converting a part of the fluorine-containing copolymer into a curing reactive site, after copolymerizing a monomer having a hydrolyzable ester bond after polymerization,
There is a method of hydrolyzing to exchange with a carboxylic acid group or a hydroxyl group. Further, as a method of introducing a curing site by reacting a compound with a fluorine-containing copolymer, a method of introducing a carboxylic acid group by reacting a polyvalent carboxylic acid anhydride with a fluorine-containing copolymer having a hydroxyl group, a hydroxyl group Isocyanate group-containing acryloyl compound or methacryloyl compound or a fluorine-containing copolymer having a method of introducing an unsaturated group by reacting a compound such as acrylic acid chloride, a fluorine-containing copolymer having an epoxy group, polyvalent Reacting a carboxylic acid anhydride to form a hydroxyl group and a carboxylic acid group,
Examples include a method of reacting phenol to introduce a hydroxyl group.

The fluorocopolymer in the present invention has an intrinsic viscosity of 0.05 to 2.0 dl / g measured at 30 ° C. in tetrahydrofuran. If the intrinsic viscosity is too small, the physical properties of the coating film cannot be sufficiently obtained, and the thickness of the coating film cannot be sufficiently obtained, which is not preferable. If the intrinsic viscosity is too large, the workability is deteriorated, which is not preferable.

The composition of the present invention contains another curing agent of the above-mentioned fluorine-containing copolymer. A coating film that is tough and has excellent solvent resistance can be obtained. The curing agent is a compound having a group capable of reacting with the curing reactive site of the fluorocopolymer,
Those that react with the fluorine-containing copolymer to give a good cured product are used. Examples of such a curing agent include polyisocyanate type, aminoplast, polybasic acid anhydride metal alkoxide, polyvalent amine compound and the like. As a polyisocyanate system, a polyisocyanate compound such as hexamethylene diisocyanate, a silyl isocyanate compound such as methylsilyltriisocyanate, a partial condensate of these, a multimer, or an isocyanate group blocked with phenol or the like. Examples include block polyisocyanate compounds blocked with an agent. Particularly, a non-yellowing type is preferably used. As the aminoplast, melamine resin, guanamine resin, urea resin and the like are adopted. Among them, methanol, ethanol,
Melamine at least partially etherified with one or more lower alcohols such as propanol and butanol is preferably used. Examples of polybasic acid anhydrides include aromatic polyvalent carboxylic acid anhydrides such as phthalic anhydride and pyromellitic anhydride, and aliphatic polyvalent carboxylic acid anhydrides such as maleic anhydride and succinic anhydride.

The composition of the present invention may contain various additives and the like, if necessary, in addition to the above components. Examples of such additives include solvents, synthetic resins, curing catalysts, heat stabilizers, leveling agents, lubricants, pigments, dyes, viscosity modifiers, dispersion stabilizers, gelation inhibitors, and the like. In particular, when used for coating such as paint, it is preferable that each component is dispersed or dissolved in an appropriate solvent. As such a solvent, both polar and non-polar solvents can be used, xylene, aromatic hydrocarbons such as toluene, alcohols such as n-butanol, esters such as butyl acetate, ketones such as methyl isobutyl ketone, In addition to glycol ethers such as ethyl cellosolve, various commercially available thinners can be adopted, and these can also be mixed and used at various ratios. As the synthetic resin, an acrylic resin, a phenol resin, an epoxy resin, a polyimide resin, a polyamide resin, a polyether resin, a silicone resin, or an elastomeric material such as polyurethane or an acrylic elastomer is used. Moreover, these precursors may be blended. Preferably, it has a group similar to or capable of reacting with the curing reactive site of the fluorine-containing copolymer.

[Examples] The present invention will be specifically described below with reference to Examples.
The present invention is not limited to the embodiments.

Synthesis Example 1 50 parts by weight of xylene, 50 parts by weight of methyl isobutyl ketone, based on 100 parts by weight of a fluorine-containing copolymer obtained by copolymerizing tetrafluoroethylene, ethyl vinyl ether and glycidyl vinyl ether in the proportions of 50, 40 and 10 mol%, respectively. 2,
36 parts by weight of 4-dihydroxybenzophenone and 1 part by weight of triphenylphosphine were added and the reaction was carried out at 120 ° C. for 6 hours to obtain a fluorine-containing copolymer A-1 having UVAC. This fluorine-containing copolymer in tetrahydrofuran at 30 ° C
Intrinsic viscosity measured by was 0.22 dl / g.

Synthesis Examples 2 to 8 A fluorine-containing copolymer having a copolymerization composition (mol%) shown in Table 1 was reacted with 2,4-dihydroxybenzophenone in the same manner as in Synthesis Example 1 to give a fluorine-containing copolymer having UVAC. Copolymers A-2 to A-8 were obtained.

In Table 1, the figures of the fluorine-containing copolymer composition are mol%.

Synthesis Example 9 Units based on tetrafluoroethylene, ethyl vinyl ether and hydroxybutyl vinyl ether are respectively
100 parts by weight of xylene and 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) -5-based on 100 parts by weight of the fluorine-containing copolymer contained at 50, 30, 20 mol%. 35 parts by weight of chlorobenzotriazole was added, and the mixture was reacted at 140 ° C. for 7 hours to obtain a fluorine-containing copolymer A-9 having UVAC.
The intrinsic viscosity of this fluorine-containing copolymer measured in tetrahydrofuran at 30 ° C. was 0.16 dl / g.

Synthesis Example 10 46 parts by weight of glycidyl vinyl ether and 214 parts by weight of 2,4-dihydroxybenzophenone were reacted in xylene in the presence of triphenylphosphine at 120 ° C. for 5 hours to give U.
A vinyl monomer having VAC was obtained.

In an autoclave, in the presence of methyl isobutyl ketone, chlorotrifluoroethylene, hydroxybutyl vinyl ether, cyclohexyl vinyl ether, and the vinyl monomer having UVAC above 40,1 respectively.
After charging 5,35,10 mol, polymerization was carried out at 70 ° C. for 10 hours in the presence of azoisobutyronitrile to obtain a fluorine-containing copolymer A-10 having UVAC. The intrinsic viscosity of this fluorinated copolymer measured at 30 ° C. in tetrahydrofuran was 0.23 dl / g.

Examples 1 to 9 Comparative Example 1 Solubility of the fluorine-containing copolymers A-1 to A-10 having UVAC obtained in the above-described Synthesis Examples 1 to 10 in xylene and methyl ethyl ketone (dissolved: ○, partially dissolved Is Δ, insoluble is x), and a fluorine-containing copolymer having each UVAC
100 parts by weight of Solvesso 150, 25 parts by weight of cyclohexanone, and 10 parts by weight of Epomate B-002 (curing agent for epoxy made by Yuka Shell Co., Ltd.) were mixed to give a coating of 25 μm thickness on a glass plate. It was applied and cured at 200 ° C. for 60 seconds to obtain a test piece. Table 2 shows the surface gloss of this test piece, the absorptance of light having a wavelength of 350 mm, the surface condition after 250 hours of the duty cycle, and the absorptance of light having a wavelength of 350 mm.

Comparative Example 2 100 parts by weight of fluorinated copolymer A-11 in which chlorotrifluoroethylene, cyclohexyl vinyl ether, ethyl vinyl ether, and glycidyl vinyl ether were copolymerized in the proportions of 50, 15, 15, and 20 mol%, respectively, Solvesso 15
0 100 parts by weight, cyclohexanone, 25 parts by weight, Coronate 2507 (manufactured by Nippon Polyurethane Co .; blocked isocyanate), 18 parts by weight, 0.03 parts by weight of dibutyltin dilaurate, 20 parts by weight of 2,4-dihydroxybenzophenone , 25μ film thickness on a glass plate, 200 ℃
After curing for 60 seconds, a test piece was obtained. Table 2 shows the surface gloss of this test piece (gloss at 60 ° C.), the absorptance of light having a wavelength of 350 mm, the surface state after a duty cycle / 250 hours, and the absorptance of light having a wavelength of 350 mm.

EFFECTS OF THE INVENTION The composition of the present invention is soluble in various solvents, and provides a coating film having excellent surface gloss and ultraviolet absorption, and therefore, various protective coatings, particularly for outdoor synthetic resin coating. It is extremely useful as a paint. In addition, since a cured coating film is formed using a curing agent, a coating film further excellent in solvent resistance and the like can be obtained, and the surface of the coating film can be washed using a solvent.

Claims (1)

[Claims] 1. A fluororesin coating composition containing the following (a) and (b): (A) Fluorine content based on fluoroolefin is 10
% By weight or more, having 30 to 70 mol% of polymer units based on alkyl vinyl ether or alkyl vinyl ester with respect to all polymer units, and having a polymer unit containing a group having an ultraviolet absorbing ability to 0.5 to all polymer units. It has 50 mol% and the intrinsic viscosity measured at 30 ° C. in tetrahydrofuran is 0.05 to
2.0 dl / g fluorinated copolymer (b) Curing agent