JPH11302334A - Fluorocopolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new fluorocopolymer with excellent storage stability, capable of affording coating film with a combination of high gloss with weatherability when used as a coating resin. SOLUTION: This new fluorocopolymer is such one that the respective proportions of the essential constituent units are as follows (based on the total amount of all of the monomer units): (a) a fluoroolefin: 10-70 mol.%, (b) cyclohexyl acrylate optionally bearing substituent (s) on the cyclohexyl group: 20-80 mol.%, and (c) a hydroxyalkyl acrylate and/or a hydroxyalkyl crotonate: 1-30 mol.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorine-containing copolymer, and this copolymer is particularly useful as a resin and a film for a weather-resistant paint.

[0002]

2. Description of the Related Art Fluorine-containing copolymers which are soluble in an organic solvent and contain a hydroxyl group are used in various applications as coating materials having extremely high durability. As this kind of fluorinated copolymers, those containing a fluoroolefin, a hydroxyl group-containing monomer and other radically polymerizable monomers as essential components have been proposed (JP-A-57-34107, JP-A-61-57609 and JP-A-3-2609
No. 31906), among which the hydroxyl group-containing monomer is a component for providing a tough coating film by crosslinking with a curing agent such as an isocyanate compound and melamine. However,
Fluorine-containing copolymers using hydroxyalkyl vinyl ethers or hydroxyalkyl allyl ethers as hydroxyl group-containing monomers have poor storage stability and have a problem of gelling due to acids generated during storage. In addition, paints based on such a fluorine-containing copolymer have excellent weather resistance, and have the feature that the coating film gloss does not decrease even after long-term exposure, but the coating film gloss in the initial stage of coating is lower than that of the acrylic urethane paint. Therefore, a fluorinated copolymer capable of obtaining high coating film gloss has been desired.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel copolymer having excellent storage stability and, for example, high gloss and weather resistance when used as a coating resin. An object of the present invention is to provide a fluorine-containing copolymer which forms a coating film having the same function.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that fluoroolefins, cyclohexyl acrylates which may have a substituent on the cyclohexyl group, hydroxyalkyl acrylates and / or crotonic acid. The present inventors have found that a fluorine-containing copolymer containing a hydroxyalkyl ester as an essential component solves the above problems, and have completed the present invention. That is, in the present invention, the ratio of the essential constituent monomers based on the total amount of all the monomers is (a) 10
To 70 mol%, (b) cyclohexyl acrylate which may have a substituent in cyclohexyl group: 20 to 8
0 mol%, and (c) hydroxyalkyl acrylate and / or hydroxyalkyl crotonate: 1 to 30 mol%.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. Examples of the (a) fluoroolefin in the present invention include chlorotrifluoroethylene, tetrafluoroethylene, hexafluoropropylene, trifluoroethylene, vinylidene fluoride, and vinyl fluoride. Among these, chlorotrifluoroethylene and tetrafluoroethylene are preferable from the viewpoint of easy handling.

The (b) cyclohexyl acrylate which may have a substituent in the cyclohexyl group in the present invention includes cyclohexyl acrylate, te
Examples thereof include rt-butylcyclohexyl, hydroxymethylcyclohexyl acrylate, isobornyl acrylate, adamantyl acrylate, and tricyclodenisyl acrylate. Of these, cyclohexyl acrylate is preferable from the viewpoint of copolymerizability.

In the present invention, (c) hydroxyalkyl acrylate includes 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 3-hydroxybutyl acrylate, 4-hydroxybutyl acrylate and modified caprolactone thereof. And the like. Among them, acrylic acid 2-
Hydroxyethyl and 4-hydroxybutyl acrylate are preferred. Examples of the hydroxyalkyl crotonic acid ester include 2-hydroxyethyl crotonic acid, 3-hydroxypropyl crotonic acid and 4-hydroxy crotonic acid.
Hydroxybutyl and the like are mentioned, and among these, 2-hydroxyethyl crotonate is preferable from the viewpoint of copolymerizability. The hydroxyalkyl acrylate and the hydroxyalkyl crotonate may be used in combination of two or more.

In the present invention, the ratio of the above-mentioned essential constituent monomers of the fluorine-containing copolymer is (a): 10 to 70 mol%, and (b): 20 to 80, based on the total amount of all the monomers. Mol%, and (c): 1 to 30 mol%, preferably (a): 20 to 60 mol%, (b): 30 to 60 mol%, and (c): 5 to 20 mol%. is there. When a copolymer comprising the above essential constituent monomers is used, for example, as a coating resin, if (a) exceeds 70 mol%, the solubility of the fluorinated copolymer decreases, and if it is less than 10 mol%, If it is, the weather resistance is reduced. If (b) exceeds 80 mol%, the weather resistance decreases, and if it is less than 20 mol%, the gloss of the coating film decreases. On the other hand, when (c) exceeds 20 mol%, the weather resistance decreases, and when it is less than 1 mol%, the strength of the coating film decreases.

The fluorine-containing copolymer of the present invention may be copolymerized with other monomers as long as the physical properties are not impaired. Examples of such polymerizable monomers include ethylene, propylene and isobutylene. α-olefins, chloroethylenes such as vinyl chloride and vinylidene chloride, alkyl vinyl ethers such as ethyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether and cyclohexyl vinyl ether, vinyl propionate, vinyl caproate, and pivalic acid Vinyl, Veova-9 (trade name, manufactured by Shell Chemical Co., Ltd.), vinyl carboxylate such as vinyl cyclohexanecarboxylate and vinyl benzoate, methyl methacrylate, ethyl methacrylate and cyclohexyl methacrylate Methacrylates such relations, methyl acrylate, ethyl acrylate, Purobiru acrylate, isopropyl acrylate, n- butyl acrylate, isobutyl acrylate, s- butyl acrylate,
T-butyl acrylate, neopentyl acrylate, ethylhexyl acrylate, isodecyl acrylate, lauryl acrylate, tridecyl acrylate, stearyl acrylate, benzyl acrylate, tetrahydrofurfuryl acrylate, methoxyethyl acrylate, dimethylaminoethyl acrylate Chloroethyl acrylate, trifluoroethyl acrylate and heptadecafluorooctylethyl acrylate.

The glass transition temperature (hereinafter, referred to as Tg) of the fluorine-containing copolymer in the present invention is preferably in the range of 10 to 60 ° C., and its molecular weight is determined by gel permeation chromatography (hereinafter, referred to as GPC). The number average molecular weight (in terms of polystyrene) is preferably 3000 to 100,000, and more preferably 5000 to 50,000. Tg is 60 ° C
When the molecular weight exceeds 100, the workability of the coating film decreases, and when the molecular weight exceeds 100,000, the workability deteriorates. In any case, the usefulness as, for example, a resin for a coating material may be reduced.

The fluorinated copolymer of the present invention can be produced by a method of copolymerizing the above-mentioned components (a) to (c) in the presence of a radical-generating polymerization initiator. As the polymerization method, methods such as bulk polymerization, suspension polymerization and emulsion polymerization in an aqueous medium, and solution polymerization in an organic solvent can be adopted. Examples of radical-generating polymerization initiators include peroxides such as diisopropyl peroxydicarbonate, tertiary butyl peroxypivalate, benzoyl peroxide and lauroyl peroxide, azobisisobutyronitrile and azobisisovaleronitrile. Inorganic peroxides such as azo compounds, ammonium persulfate and potassium persulfate can be used, and the amount used is preferably in the range of 0.0001 to 10 mol% based on all monomers. Examples of the emulsifier in the emulsion polymerization include sodium perfluorooctanoic acid, potassium salt or ammonium salt, sodium or ammonium perfluorooctanesulfonate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium alkylnaphthalenesulfonate, and dialkylsulfosuccinate. Examples thereof include sodium acid, sodium polyoxyethylene alkyl ether sulfate, and sodium alkane sulfonate, and the amount thereof is preferably in the range of 0.1 to 50 parts by weight based on 100 parts by weight of the total amount of monomers. . Examples of the organic solvent in the solution polymerization include cyclic ethers such as tetrahydrofuran and dioxane; hydrocarbons such as mineral terpene and cyclohexane; aromatic hydrocarbon compounds such as benzene, toluene and xylene; esters such as ethyl acetate and butyl acetate; Ketones such as acetone, metholethylketone and cyclohexanone; methanol, ethanol, isopropanol, n-butanol and n-
Alcohols such as butyl cellosolve; freons such as 1,1,2-trichloro-1,2,2-trifluoroethane; and one or more of these can be used. The amount of the organic solvent used is preferably in the range of 20 to 200 parts by weight based on 100 parts by weight of the total amount of the monomers. Among these polymerization methods, considering that the main use form of the fluorinated copolymer in the present invention is a solution type paint, solution polymerization is suitably employed as the copolymerization method.

The polymerization conditions are not particularly limited.
The preferred polymerization temperature in the preferred reaction is 20-100 ° C
The preferred pressure is 1 to 200 kg / cm ² and the preferred polymerization time is 3 to 40 hours. The monomers used in the polymerization may be initially charged in batches at the beginning, or some of the monomers may be added sequentially as the polymerization proceeds. Also,
If necessary, potassium carbonate, sodium hydrogen carbonate, hydrotalcite, an anion exchange resin and the like may be added as a pH adjuster.

The fluorine-containing copolymer obtained by the present invention is used as a room temperature-curable paint or a heat-curable paint by using an appropriate curing agent in combination. The curing agent is a compound having a plurality of reactive groups with hydroxyl groups in one molecule, such as a polyvalent isocyanate compound or an aminoplast resin. Examples of the polyvalent isocyanate compound include hexamethylene diisocyanate, isophorone diisocyanate, and blocked isocyanate.
Examples of the aminoplast resin include melamine resins such as methylated melamine and butylated melamine, benzoguanamine resins and urea resins. The preferred amount of the polyvalent isocyanate compound is such that the isocyanate group derived from the isocyanate compound is substantially equimolar to the hydroxyl group derived from the fluorine-containing copolymer, and when an aminoplast resin is used, the fluorine-containing It is preferably about 10 to 30 parts by weight per 100 parts by weight of the copolymer. In addition, together with these curing agents, dibutyltin dilaurate or p
-A compound that promotes a curing reaction such as toluenesulfonic acid may be used.

In preparing the paint, a pigment such as titanium oxide, iron oxide, phthalocyanine blue, benzidine yellow, quinacridone red and carbon black, a metal such as stainless steel powder, aluminum powder and bronze powder are added to a solution of the fluorocopolymer. Various additives such as powder, a pigment dispersant, an ultraviolet absorber and a surface conditioner, and other resins may be added as required. When the fluorinated copolymer is used as a varnish, the solid content concentration is 4%.
The content is preferably set to 0 to 60% by weight. The coating composition obtained from the fluorine-containing copolymer is usually used in the coating field.
It can be used in a conventional method, and for example, it can be applied to a coating substrate such as a steel plate, stainless steel, aluminum, concrete, mortar, plastic and wood by spraying, brushing and rolling.

The present invention will be described more specifically with reference to the following Examples and Comparative Examples.

Example 1 (1) Preparation of fluorinated copolymer In a 1.5 liter autoclave equipped with a stirrer, 200 g of xylene, 16 g of cyclohexyl acrylate (hereinafter referred to as CHA), 2-hydroxyethyl crotonate were added. After charging 20 g (hereinafter referred to as HE) and replacing the space with nitrogen gas, 280 g of chlorotrifluoroethylene (hereinafter referred to as CTFE) was added,
The autoclave was heated to 40 ° C. Then, a mixed solution of 100 g of xylene, 147 g of CHA, 37 g of 4-hydroxybutyl acrylate (hereinafter, referred to as HBA) and 30 g of xylene, di-2-ethoxyethylperoxydicarbonate [Perloyl EEP manufactured by NOF Corporation, hereinafter, 6 g of a mixed solution was charged by a high-pressure constant-flow micropump over 6 hours. Thereafter, the temperature was maintained at 40 ° C. while stirring for 6 hours. Unreacted C
Purge the TFE, open the autoclave and allow 720
g of a polymerization reaction solution was obtained.

(2) Evaluation of Physical Properties of Fluorine-Containing Copolymer A part of the above polymerization reaction solution was taken and the number average molecular weight of the copolymer (gel permeation chromatography), fluorine content (fluorine quantitative analysis) and Measurement of hydroxyl value and nuclear magnetic resonance analysis were performed. As a result, the number average molecular weight was 120
00 (in terms of polystyrene), the fluorine content is 21.4
Weight%, hydroxyl value 59 (mg-KOH / g-resin)
Met. Further, when the composition of the polymer was analyzed together with the measurement results of ¹ H-NMR and ¹³ C-NMR,
The composition of the copolymer is CTFE / CHA / HBA / HE =
It was confirmed to be 50/36/9/5 (mol%).

(3) Evaluation of fluorinated copolymer and paint film The above polymerization reaction solution was placed in a glass bottle, sealed and then sealed at 60 ° C.
As a result, the viscosity was not increased even after 30 days, and the initial viscosity was maintained. 30 g of xylene and 20 g of titanium oxide are added to 50 g of the above polymerization reaction solution.
Then, 0.4 g of Disperbic-110 (manufactured by Big Chemie) as a pigment dispersant was added, and the mixture was mixed with a paint conditioner for 1 hour. To this solution, 0.3 mg of dibutyltin dilaurate and 6.2 g of Coronate HX (manufactured by Nippon Polyurethane Industry Co., Ltd.) [NCO / OH = 1/1
(Equivalent ratio)] to prepare a coating composition. The obtained composition for coating was applied to a chromate-treated aluminum plate having a thickness of 0.6 mm with a bar coater, allowed to dry naturally at room temperature for one week, and cured to obtain a coating film having a thickness of 20 μm. The coating film was evaluated by JIS-K5400 and various conventional methods, and the results are shown in Table 1 below.

Example 2 (1) Preparation of Fluorine-Containing Copolymer In a 1.5-liter autoclave equipped with a stirrer, 200 g of xylene and 4-tert-butylcyclohexyl acrylate (hereinafter referred to as t-BCHA) 2
After charging 2 g and 20 g of HE and replacing the space with nitrogen gas, 280 g of CTFE was added, and the autoclave was cooled to 40 g.
Heated to ° C. Then, 100 g of xylene, t-BCH
A mixed solution of 200 g of A, 18 g of acrylic acid 2-hydroxyethyl ester (hereinafter referred to as HEA), and a mixed solution of 30 g of xylene and 6 g of EEP were each charged over 6 hours by a high-pressure constant flow micropump. Thereafter, the temperature was maintained at 40 ° C. while stirring for 6 hours. Unreacted CTF
E was purged, and the autoclave was opened to obtain 740 g of a polymerization reaction solution.

(2) Evaluation of Physical Properties of Fluorine-Containing Copolymer A portion of the above polymerization reaction solution was taken and the physical properties were evaluated in the same manner as in Example 1. As a result, the number average molecular weight was 15,000 and the fluorine content was 18. 6% by weight and a hydroxyl value of 42.
The composition of the copolymer is CTFE / t-BCHA / HEA /
It was confirmed that HE = 50/40/5/5 (mol%).

(3) Evaluation of fluorinated copolymer and paint film The above polymerization reaction solution was placed in a glass bottle, sealed and then sealed.
As a result of examining the change in viscosity over time while keeping the temperature at ° C, no increase in viscosity was observed even after 30 days, and the initial viscosity was maintained. A coating film was prepared in the same manner as in Example 1, and the coating film was evaluated. The results are shown in Table 1.

Example 3 (1) Preparation of Fluorine-Containing Copolymer In a 1.5-liter autoclave equipped with a stirrer, 200 g of xylene, 10 g of CHA, and 4 g of ethyl acrylate (hereinafter referred to as EA) were charged, and nitrogen gas was used. After replacing the space, 280 g of CTFE was added, and the autoclave was heated to 40 ° C. Then, xylene 100
g, 90 g of CHA, 37 g of EA, and 40 g of HEA and a mixed solution of 30 g of xylene and 6 g of EEP were charged over 6 hours by a high-pressure constant flow micropump. Thereafter, the temperature was maintained at 40 ° C. while stirring for 6 hours.
Unreacted CTFE was purged, and the autoclave was opened to obtain 670 g of a polymerization reaction solution.

(2) Evaluation of Physical Properties of Fluorine-Containing Copolymer A portion of the above polymerization reaction solution was subjected to physical properties evaluation in the same manner as in Example 1. As a result, the number average molecular weight was 14,000 and the fluorine content was 23. The hydroxyl value was 3% by weight and the hydroxyl value was 56.
The composition of the copolymer is CTFE / CHA / EA / HEA =
It was confirmed to be 50/23/15/12 (mol%).

(3) Evaluation of Fluorine-Containing Copolymer and Paint Film The above polymerization reaction solution was placed in a glass bottle, sealed and then sealed.
As a result of examining the change in viscosity over time while keeping the temperature at ° C, no increase in viscosity was observed even after 30 days, and the initial viscosity was maintained. A coating film was prepared in the same manner as in Example 1, and the coating film was evaluated. The results are shown in Table 1.

Comparative Example 1 (1) Preparation of Fluorine-Containing Copolymer In a 1.5-liter autoclave equipped with a stirrer, 200 g of xylene and 16 g of CHA were charged, the space was replaced with nitrogen gas, and 280 g of CTFE was added. Was heated to 40 ° C. Then, xylene 100
g, 147 g of CHA, 40 g of 4-hydroxybutyl vinyl ether (hereinafter referred to as HBVE) and a mixed solution of 30 g of xylene and 6 g of EEP were charged over 6 hours by a high-pressure constant flow micropump. Then 6
While stirring for an hour, the temperature was maintained at 40 ° C. Purge unreacted CTFE, open autoclave,
0 g of a polymerization reaction solution was obtained.

(2) Evaluation of Physical Properties of Fluorine-Containing Copolymer An aliquot of the above polymerization reaction solution was subjected to physical properties evaluation in the same manner as in Example 1. As a result, the number average molecular weight was 16,000 and the fluorine content was 21. 8% by weight and hydroxyl value were 52.
The composition of the copolymer is CTFE / CHA / HBVE = 50
/ 38/12 (mol%).

(3) Evaluation of Fluorine-Containing Copolymer and Paint Film The above polymerization reaction solution was placed in a glass bottle, sealed and then sealed.
As a result of examining the change in viscosity over time while maintaining the temperature at 0 ° C, gelation was observed after 10 days. A coating film was prepared in the same manner as in Example 1, and the coating film was evaluated. The results are shown in Table 1.

Comparative Example 2 (1) Preparation of Fluorine-Containing Copolymer In a 1.5-liter autoclave equipped with a stirrer, 200 g of xylene and 13 g of cyclohexylvinyl ether (hereinafter referred to as CHVE) were charged, and the space was replaced with nitrogen gas. After that, 280 g of CTFE was added, and the autoclave was heated to 40 ° C. Then, 100 g of xylene,
A mixed solution of 120 g of CHVE and 50 g of HBA and a mixed solution of 30 g of xylene and 6 g of EEP were charged over 6 hours by a high-pressure constant flow micropump. Thereafter, the temperature was maintained at 40 ° C. while stirring for 6 hours. Unreacted CT
Purge FE, open autoclave, 675g
Was obtained.

(2) Evaluation of Physical Properties of Fluorine-Containing Copolymer An aliquot of the above polymerization reaction solution was subjected to physical property evaluation in the same manner as in Example 1. As a result, the number average molecular weight was 16,000, and the fluorine content was 23.0. 1% by weight and a hydroxyl value of 56.
The composition of the copolymer is CTFE / CHVE / HBA = 50
/ 38/12 (mol%).

(3) Evaluation of Fluorine-Containing Copolymer and Paint Film The above polymerization reaction solution was placed in a glass bottle, sealed and then sealed.
As a result of examining the change in viscosity over time while maintaining the temperature at 0 ° C, gelation was observed after 3 days. A coating film was prepared in the same manner as in Example 1,
The coating film was evaluated, and the results are shown in Table 1.

[0030]

[Table 1] * 1 60 ° gloss: measured by the method described in JIS-K5400. * 2 Pencil hardness: Tested by the method described in JIS-5400. * 3 Solvent resistance: A xylene rubbing test was performed using a rubbing tester. * 4 Accelerated weathering resistance: The gloss retention after a 3000 hour test using the fluorescent ultraviolet ray wetting cycle tester under the following conditions. Dark / irradiation cycle: 4 hours / 4 hours Temperature / humidity condition: Irradiation 63 ° C, 50% RH Dark 50 ° C, 98% RH or more

[0031]

Industrial Applicability The fluorine-containing copolymer of the present invention not only has excellent storage stability, but also has excellent weather resistance and high glossiness. High utility value.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hiroshi Inukai 1 in Funami-cho, Minato-ku, Nagoya-shi, Aichi, Japan

Claims (1)

[Claims] (1) The ratio of the essential constituent monomers based on the total amount of all the monomers is (a) fluoroolefin: 10 to 70
Mol%, (b) cyclohexyl acrylate which may have a substituent in the cyclohexyl group: 20 to 80 mol%, and (c) hydroxyalkyl acrylate and / or hydroxyalkyl crotonate: 1 to 30 mol. % Of the fluorine-containing copolymer.