JPH02107677A - Fluorine-containing resin composition for paint - Google Patents

Abstract

PURPOSE:To obtain the subject composition having excellent flexibility and soluble in organic solvent by compounding a fluoroolefin, a carboxylic acid vinyl ester, etc., and a polyalkylene glycol monoallyl ether at specific ratios. CONSTITUTION:The objective composition contains, as essential components, (A) 25-75mol%, preferably 40-60mol% of a fluoroolefin (preferably chlorotrifluoroethylene or tetrafluoroethylene), (B) 10-70mol%, preferably 20-50mol% in total or a carboxylic acid vinyl ester (preferably vinyl acetate or vinyl propionate) and an alkyl vinyl ether (preferably ethyl vinyl ether, n- butyl vinyl ether or isobutyl ether) and (C) 3-40mol%, preferably 5-30mol% of a polyalkylene glycol monoallyl ether (e.g. ethylene glycol monoallyl ether).

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a fluororesin composition for paints, and more particularly to a fluororesin that has excellent flexibility and is soluble in organic solvents.

(Conventional technology) Paints using conventional fluoropolymers have poor weather resistance, heat resistance,
Due to its excellent chemical resistance, it is widely used in fields such as the chemical industry, architecture, food, and machinery.

Particularly in recent years, solvent-soluble fluororesin paints with improved workability have been in the spotlight.

These paints have increased solubility in organic solvents, making them soluble in common paint solvents, and can be cured at room temperature instead of conventionally requiring baking at high temperatures. Like hydrogen-based solvent-based paints, it can be applied on-site, and due to its weather and chemical resistance, it is a long-term, maintenance-free paint that is increasingly being used for construction, civil engineering, and machinery and metals.

(Problems to be Solved by the Invention) In order to make the fluororesin soluble in organic solvents, the crystallinity of the fluororesin is usually disturbed by a method such as copolymerization,
Needs to be internally plasticized.

Furthermore, in order to use this as a paint, there are issues such as how to maintain the inherent rigidity of the resin, the molecular weight of the resin to adjust the viscosity of the paint, and the need to maintain chemical resistance and repaint. In order to make this possible, it is necessary to introduce a functional group into the resin and cure it, and in this case there are problems such as how to select the type and amount of the functional group and cost issues.

From this viewpoint, fluororesins for coatings have been proposed, including copolymers consisting of fluoroolefins, fatty acid vinyl esters, and hydroxy group-containing allyl ethers (see JP-A-61-57609).

Alternatively, there is a method of copolymerizing a monomer mixture in which a carboxyl group-containing monomer is added to the above three components (Japanese Patent Application No. 1983-
118353), and furthermore, copolymers of fluoroolefins and general alkyl vinyl ethers are disclosed in U.S. Pat.
, 834, 767. Further, JP-A-57-34107 describes a copolymer in which a functional group is introduced into a resin by copolymerizing a fluoroolefin, an alkyl vinyl ether, a cyclohexyl vinyl ether, and a hydroxyalkyl vinyl ether.

These copolymers are soluble in organic solvents, and by crosslinking with °C isocyanate hardeners and melamine hardeners using functional groups, they can be made to dissolve in the original groove shoulders. Yes, weather resistant f'L.

Although coatings and films with excellent chemical resistance can be obtained, these coatings lack flexibility.

The above-mentioned Japanese Patent Application Laid-Open No. 61-57609 and Japanese Patent Application No. 63-1]
, 8353, in a fluorine-containing resin for coatings obtained by copolymerizing a fluoroolefin, a fatty acid vinyl ester, a hydroxy-containing allyl ether, or a monomer mixture in which a carboxyl group-containing monomer is further added to the above three components. It is stated that those in which the fatty acid vinyl ester is vinyl acetate or vinyl propionate are suitable from the viewpoint of physical properties such as weather resistance and chemical resistance, and economical efficiency. However, vinyl ester g+<
M Vinyl acetate or vinyl propionate have the advantage of high hardness and scratch resistance, but
On the other hand, it is inferior in terms of flexibility and there is room for improvement.

For example, when a painted steel plate is bent or subjected to impact, cracks and peeling often occur.

Furthermore, when used as a top coat material for an elastic base material, it cannot follow the expansion and contraction of the elastic base material, which may cause paint film defects such as cracking and peeling. Therefore, in order to make better use of the weather resistance, chemical resistance, and antifouling properties of this type of solvent-soluble fluorine-containing paint resin, it is important to increase its flexibility. It's coming.

The present invention solves the above-mentioned difficulties recognized in the prior art, and provides a coating film with good weather resistance, chemical resistance, antifouling properties, etc., which is also economically advantageous, increases flexibility, and uses solvents. An object of the present invention is to provide a soluble fluororesin composition for paint.

(Means for solving the problem) As a means of increasing the flexibility of a solvent-soluble fluororesin for paint, for example, a method of imparting flexibility at the crosslinking site using a flexible curing agent. Alternatively, a method of adding an additive having a plasticizing effect may be considered. However, a curing agent with flexibility, such as an extensible curing agent for isocyanate-based polyols, "Coronate EX976"
The tensile elongation at break of a specimen made of general-purpose fluorine paint cured using (Japan Polyurethane) was as low as 70% (at room temperature).
Furthermore, since the NGO content in the curing agent is lower than that of general-purpose isocyanate curing agents, a large amount of curing agent is required, which tends to reduce the fluorine content in the coating composition and reduce the weather resistance of the coating film. On the other hand, as for additives having flexibility, JP-A-60-137950 exemplifies the addition of polytetrahydrofuran, but the same problem arises because the fluorine content is lowered by the additive. Therefore, in order to maintain physical properties such as weather resistance and chemical resistance, and to increase flexibility, it is necessary to increase the flexibility of the fluororesin itself for coatings.

From the above point of view, the present inventors have developed a monomer mixture of fluoroolefins, carboxylic acid vinyl esters, alkyl vinyl ethers, and polyalkylene glycol monoallyl ethers, or a monomer mixture in which a carboxyl group-containing monomer is further added to the above three components as necessary. As a result of intensive studies on improving the flexibility of fluorine-containing copolymers for coatings obtained from the above, it was found that the flexibility of cured coatings was improved by increasing the U4 length of the non-vinyl group of the carboxylic acid vinyl ester or by introducing an aromatic ring. Furthermore, the flexibility is improved by increasing the chain length of the C)12cHffiO group of polyalkylene glycol monoallyl ether, and furthermore, the flexibility is improved by using an alkyl vinyl ether as a comonomer. It became clear that a flexible fluororesin could be obtained by combining these factors for improving flexibility and performing molecular design, and the present invention was completed.

That is, the present invention uses Jfl acid vinyl esters of 02 to CI6 as fluoroolefins and carboxylic acid vinyl esters, or aromatic carboxylic acid vinyl esters, alkyl vinyl ethers, and polyalkylene glycol monoallyl ethers as essential components, and further contains carboxyl groups as necessary. By polymerizing a monomer mixture containing monomers and other monomers in the presence of a radical initiator, it is possible to create coatings with excellent physical properties such as weather resistance and chemical resistance, and which are also economically advantageous. It has been discovered that it is possible to produce a fluorine-containing resin for paints that maintains flexibility.

Examples of carboxylic acid vinyl esters that can be used in the present invention include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl caproate, vinyl incaproate, vinyl bivarisocate, vinyl caprylate, vinyl capricate, and stearic acid. Examples include fatty acid vinyl esters such as vinyl, and aromatic carboxylic acid vinyl esters such as vinyl benzoate and pt-butyl vinyl benzoate. Long-chain fatty acid vinyl esters are preferable in order to impart flexibility, but are economical. Considering the nature of vinyl acetate,
Combinations with vinyl propionate or vinyl butyrate are preferred.

On the other hand, examples of alkyl vinyl ethers include aqueous vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, 5,2-ethylhexyl vinyl ether, and isooctyl vinyl ether. Then ethyl vinyl ether, n-
Butyl vinyl ether and isobutyl vinyl ether are preferred.

The mixing molar ratio of these carboxylic acid vinyl esters and alkyl vinyl ethers is in the range of 9515 to 5/95, and vinyl esters such as vinyl acetate and vinyl propionate, which are inexpensive and easily available, are suitable. However, if the amount of these is too large, flexibility will be impaired, while if the amount of vinyl ether is too large, the polymer yield will decrease, so a range of 90/10 to 10/90 is preferable.

Examples of the fluoroolefins used in the present invention include trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropene, vinyl fluoride, and vinylidene fluoride. , tetrafluoroethylene are preferred.

As polyalkylene glycol monoallyl ether, ethylene glycol monoallyl ether, propylene glycol monoallyl ether, diethylene glycol monoallyl ether, dipropylene glycol monoallyl ether, triethylene glycol monoallyl ether, tripropylene glycol monoallyl ether; however, R
=H or CH, and m=2 to 4 are preferred from the viewpoint of imparting flexibility. Further, from the viewpoint of flexibility adjustment and coating film strength maintenance, a combination of m=1 and m=2 to 3 can be used.

Next, typical copolymer resins in the present invention include the total amount of fluoroolefin, carboxylic acid vinyl ester and alkyl vinyl ether, and the content of polyalkylene glycol monoallyl ether and carboxyl group-containing monomer, respectively. 25-75 mol%, 10-75 mol%
70 mol%, 3-40 mol% and 0-2O mol%, preferably 40-60 mol%, 2O-50 mol%, respectively.
mol%, 5-30 mol% and 0-10 mol%.

The content of fluoroolefin can be changed arbitrarily depending on the amount of each monomer when charging, but if it is too high, the solubility of the fluorine-containing paint resin in organic solvents will decrease, and the fluorine-containing resin will become less soluble in manufacturing. There is a problem with the yield of resin for coating materials, and conversely, when the yield is low, it is unfavorable from the viewpoint of physical properties such as weather resistance and chemical resistance.

In addition, resins for paints containing carbon fibers that have too high a total content of carboxylic acid vinyl ester and alkyl vinyl ether are unfavorable from the viewpoint of physical properties such as weather resistance and chemical resistance. Undesirable.

If the content of polyalkylene glycol monoallyl ether is too high, the molecular weight will decrease and problems will also arise in terms of production. On the other hand, if the content is too low, the curing reaction with the curing agent becomes difficult to occur, resulting in a decrease in physical properties such as chemical resistance and weather resistance, and it becomes difficult to recoat. Furthermore, if the proportion of the carboxyl group-containing monomer is too high, the water resistance, solubility of the fluorine-containing paint resin, and reaction yield will be poor.

The resin for fluorine-containing paints of the present invention may be cyclic ethers such as tetrahydrofuran and dioxane, aromatic hydrocarbon solvents such as benzene and toluene, ester solvents such as ethyl acetate and butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, It can be dissolved in ketone solvents such as cyclohexanone, amide solvents such as dimethylformamide and dimethylacetamide, and halogen-containing solvents such as 1,1,1-trichloroethane and trichlorethylene.

Fluorine-containing paint obtained by copolymerizing the fluoroolefin, carboxylic acid vinyl ester, alkyl vinyl ether, polyalkylene glycol monoallyl ether of the present invention, or a monomer mixture obtained by adding a carboxyl group-containing monomer to the above four components The resin can be produced by any method such as solution polymerization, emulsion polymerization, suspension polymerization, or bulk polymerization in the presence of a conventional radical initiator.

The polymerization temperature in the production of resin for fluorine-containing paints varies depending on the type of polymerization initiator, but is between -30 and 130°C,
Preferably, 0 to 100°C is appropriate.

The radical initiator is an oil-soluble radical initiator such as diisopropyl peroxydicarbonate, di-normal propyl peroxydicarbonate, tertiary butyl peroxybivalate, di-2-ethylhexyl peroxydicarbonate, benzoyl peroxide, lauroyl peroxide. , propionyl peroxide, trichloroacetyl peroxide, perfluorobutyryl peroxide, perfluorooctanoyl peroxide, etc., abbisisobutyronitrile, azobis-
Examples include azo compounds such as 2,4-dimethylvaleronitrile, and organic boron compounds such as triethylboron-oxygen or peroxide.

The purity of the monomer may be less than 98% by gas chromatography as long as it does not contain any impurities that do not interfere with normal radical polymerization.

The fluorine-containing coating resin thus obtained has active hydrogen in its molecular chain, and therefore can be cured with a compound having a functional group that reacts with active hydrogen. That is, by adding polyvalent isocyanate a to a solution in which a fluorine-containing paint resin is dissolved in the above-mentioned solvent and scattering the solvent, the reaction proceeds at room temperature. The curing reaction progresses by treatment at a temperature above the dissociation of the , and a cured coating film is obtained. It also reacts with melamine, urea resin, polybasic acids or their anhydrides at high temperatures to form a cured coating film. Furthermore, the solution of this fluorine-containing paint resin contains
It is also possible to add pigments, ultraviolet absorbers, dispersion stability, etc., and good dispersibility is exhibited in either case.

Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 90.3 g of vinyl acetate (νAc), 75.6 g of ethyl vinyl ether (EVE), and 87.6 g of diethylene glycol monoallyl ether (DEGMAE) were placed in a stainless steel autoclave with a capacity of 1.41 and equipped with a magnetic stirrer.
g.

3.1 g of Perloil NPP (Nippon Oil & Fats brand), 366.9 g of butyl acetate (BAC) and 6.1 g of sodium borate were charged, and the inside of the autoclave was heated with nitrogen gas for 30 minutes.
Degassed twice. Then chlorotrifluoroethylene (
After introducing 384.4 g of CTFE into the autoclave, the temperature was gradually raised. The molar ratio of Naori Ac and EVE is 5
It was 0-50. After polymerization at 40°C for 24 hours,
Unreacted CTFf! was removed and the autoclave was opened. Next, take out the polymerization solution and remove impurities by washing with water.
After drying, 440 g of copolymer resin (yield 72%) was obtained. The molecular weight (Mn) of the obtained resin was 17,000 (number average molecular weight in terms of polystyrene), and the 011 valence was 51■KO
It was H/g.

Examples 2 to 7 and Comparative Examples 1 to 2 In the same manner as in Example 1, the copolymerization composition shown in Table 1 was prepared (however, the amount of Verloyl NPP charged was 1 wtχ/monomeric pair).
The polymerization reaction was carried out in Table 1, and the results such as yield, molecular weight, OH value, and acid value are shown in Table 1.

The fluorine-containing resins for paints obtained in Examples 1 to 7 and Comparative Examples 1 to 2 were dissolved in butyl acetate (BAc) and the resin solid content concentration was adjusted to 50%. Next, an amount of isocyanate (Coronate EH, Nippon Polyurethane) was added in an amount corresponding to the OOH value, and the mixture was applied onto a glass plate using an applicator, and placed in a gear oven to undergo a curing reaction at 150°C for 730 minutes. A cured film was obtained. The obtained cured film was peeled off from the glass plate and used as a sample for measuring strength and elongation. It was also coated on a chromate-treated aluminum plate, subjected to the same treatment, and its adhesion and hardness were measured.

The results are shown in Table 2.

(Table 2 below: Coating film physical properties Tables 1 and 2 show that the coating films of Examples 1 to 7 exhibit well-balanced physical properties, but the elongation rate in Comparative Example 1 is small, and the elongation rate in Comparative Example 2 is However, the yield was poor, the tensile strength was low, and the physical properties of the coating film were not favorable.

(Effects of the Invention) The fluorine-containing resin composition of the present invention is soluble in ordinary organic solvents and forms a cured coating film with flexibility, so cracks and peeling occur upon impact. It is suitable as a paint that exhibits weather resistance, chemical resistance, antifouling properties, etc. without causing coating film defects.

l5 Cellotape peeling test described in 5400

Claims (1)

[Claims] 1) 25 to 75 mol% of fluoroolefins, the total amount of carboxylic acid vinyl ester and alkyl vinyl ether is 1
A fluorine-containing resin composition for coating material containing 0 to 70 mol% and 3 to 40 mol% of polyalkylene glycol monoallyl ether as essential components. 2) Carboxylic acid vinyl ester is CH_3 (CH_2
)_nCOOCH=CH_2 The fluorine-containing resin composition for paint according to claim 1, wherein n=0 to 14. 3) Alkyl vinyl ether is CH_2=CHO(C
H_2)_nCH_3 However, claim 1 where n=0 to 3
The fluorine-containing resin composition for paint described above. 4) Polyalkylene glycol monoallyl ether is C
H_2=CHCH_2O(CHR-CH_2O)_mH
The fluororesin composition for paint according to claim 1, wherein R=H or CH_3 and m=2 to 4.