JP2000136330A - Fluoro electrodeposition coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electrodeposition coating material which can give a coating film excellent in long-term stability and weatherability by using a fluoro- copolymer having a specified composition and prepared by neutralizing at least part of the carboxyl groups of a carboxy fluoro copolymer with a basic compound. SOLUTION: A copolymer is used which is prepared by neutralizing at least part of the carboxyl groups of a copolymer comprising 35-65 mol% (A) fluoroolefin, 5-45 mol% (B) cyclic monomer having an unsaturation in the ring, 1-30 mol% (C) polymer units derived from an allyl ether having a curable site, or from an olefin or allyl alcohol having a curable site, 1-30 mol% (D) polymer units having carboxyl groups, and 0-40 mol% (E) polymer units derived from an olefin selected from among ethylene, propylene, and isobutylene with a basic compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorine-based electrodeposition paint which gives a paint having excellent long-term stability and excellent weather resistance.

[0002]

2. Description of the Related Art In recent years, environmental problems have become an important issue, and water-based paints have been required instead of solvent-based paints. Aqueous paints are also known, in addition to emulsion paints based on emulsions produced by emulsion polymerization, those in which a carboxylic acid group-containing polymer is neutralized with a basic compound and dissolved or dispersed in water. The latter, dissolved or dispersed in water, can be automatically applied as a coating on aluminum building materials.
It is widely used in the field of electrodeposition coating without solvent volatilization, and mainly uses a coating using an acrylic polymer.

[0003]

Fluorine-based electrodeposition paints have been proposed so far (JP-A-62-59676;
JP-A-7-238116, JP-A-4-323276, JP-A-4-332709), and there are problems such as difficulty in long-term stability of the paint due to the inclusion of an ester bond. Also,
Improvement in hardness has been desired in order to improve the scratch resistance of the coating film surface. An object of the present invention is to provide a fluorine-based electrodeposition coating material which is excellent in long-term stability of a coating material and gives a coating film having excellent weather resistance.

[0004]

The present invention provides (a) a polymerized unit based on a fluoroolefin, and (b) a polymerized unit based on a cyclic monomer having an unsaturated group in a ring copolymerizable with the fluoroolefin. , (C) polymerized units based on allyl ethers having curable sites, olefins or allyl alcohols having curable sites, (d) polymerized units having carboxyl groups, and optionally (e) ethylene, propylene and isobutylene. It comprises polymerized units based on one or more selected olefins, and the ratio of each polymerized unit to the total of all polymerized units is (a) 35 to 65 mol%,
(B) 5 to 45 mol%, (c) 1 to 30 mol%, (d)
Fluorine containing a fluorine-based copolymer obtained by neutralizing at least a part of the carboxyl group of a fluorine-based copolymer having 1 to 30 mol% and (e) 0 to 40 mol% with a basic compound It is a system electrodeposition paint.

In the following description, a fluorine-based copolymer having a carboxyl group before neutralization with a basic compound is referred to as “fluorine-based copolymer A”, and at least one of the carboxyl groups of the fluorine-based copolymer A is included. A fluorine-based copolymer obtained by neutralizing a part with a basic compound is referred to as “fluorine-based copolymer B”.

The fluorinated copolymer A in the present invention comprises:
(A) polymerized units based on fluoroolefins, (b)
A polymerized unit based on a cyclic monomer having an unsaturated group in a ring copolymerizable with a fluoroolefin, (c) an allyl ether having a curable site, a polymerized unit based on an olefin having a curable site or allyl alcohol , (D)
A polymerized unit having a carboxyl group and optionally (e) 1 selected from ethylene, propylene and isobutylene
It is a copolymer comprising polymerized units based on at least one kind of olefin. The polymerized unit (e) is an arbitrary polymerized unit, and may or may not be contained in the fluorine-based copolymer A.

The polymerized unit (a) is based on fluoroolefins. Examples of the fluoroolefins include carbons such as tetrafluoroethylene, chlorotrifluoroethylene, trifluoroethylene, vinylidene fluoride, hexafluoropropylene, and pentafluoropropylene. Fluoroolefins of Formulas 2 to 3 are exemplified. Preferred fluoroolefins are perhaloolefins such as tetrafluoroethylene and chlorotrifluoroethylene.

The polymerized unit (b) is based on a cyclic monomer having an unsaturated group in a ring copolymerizable with a fluoroolefin, and the fluorine-based copolymers A and B in the present invention have a main chain of Has this ring. Having a ring in the main chain of the copolymer means that at least one of the carbon atoms constituting the ring is a carbon atom in the carbon chain constituting the main chain of the copolymer.

The cyclic monomer giving the polymerized unit (b) is not limited as long as it is a monomer having a cyclic unsaturated group which can be copolymerized with a fluoroolefin, and this ring is an aliphatic ring or Compounds that are heterocycles are preferred.

The compound in which the above-mentioned ring is an aliphatic ring includes:
Ethyl 3-phenyl-2,5-norbornadiene-2-carboxylate, 2-acetoxy-3-phenyl-2,5-
Norbornadienes selected from 2,5-norbornadienes and 2,5-norbornadienes having an ester bond or an aryl group such as norbornadiene, ethyl 2,5-norbornadien-2-carboxylate, and 5-ethylbicyclo [2.2. 1] Hept-2-ene, 5-ethylidenebicyclo [2.2.1] hept-2
-Ene, 5-vinylbicyclo [2.2.1] hept-2
-Ene, 5-allylbicyclo [2.2.1] hept-2
-2-norbornene having an alkenyl group such as -ene,
2-norbornene having an aryl group such as 3-phenyl-2-norbornene, norbornenes selected from 2-norbornene and the like, compounds having two or more aliphatic rings such as dicyclopentadiene, or cyclohexene, cyclopentene and cyclopentadiene And other compounds having one aliphatic ring.

In the case of 2-norbornenes having an alkenyl group, the unsaturated group in the ring is polymerized, but the alkenyl group has low polymerizability and remains after polymerization, so that it can be oxidized and converted to an epoxy group or the like. It can also be used as it is as a crosslinking site. Examples of the compound in which the ring is a heterocyclic ring include dihydrofuran, furan, γ-pyran, pyrrole, thiophene, and the like.

From the viewpoint of polymerizability, 3-phenyl-2,5
-Ethyl norbornadiene-2-carboxylate, 2,5-
Ethyl norbornadiene-2-carboxylate, 5-ethylidenebicyclo [2.2.1] hept-2-ene, 5-vinylbicyclo [2.2.1] hept-2-ene, 2,5
-Norbornadiene and 2-norbornene are preferred.
More preferred are 2,5-norbornadiene and 2-norbornene.

As the monomer giving the polymerized unit (c), an allyl ether having a curable site, an olefin having a curable site, or allyl alcohol is employed from the viewpoint of polymerizability and storage stability. The polymerized unit (c) is based on a monomer having no ring or, in the case of having a ring, a monomer having no unsaturated group capable of copolymerizing with a fluoroolefin in the ring, and the polymerized unit (b) Is different from

Examples of the hardening site include a hydroxyl group, an epoxy group, a carboxyl group, a carboxylic anhydride group, a hydrolyzable silyl group, an amino group, a carbonyl group, an ester group, a mercapto group, and an aldehyde group. Among them, a hydroxyl group, an epoxy group and a carboxyl group are preferred.

Considering availability and reactivity with a curing agent, the curable site in allyl ethers is preferably a hydroxyl group or an epoxy group, and the curable site in olefins is preferably a carboxyl group. The olefins preferably have no fluorine atom.

As the allyl ether having a hydroxyl group, hydroxyalkyl allyl ethers such as hydroxyethyl allyl ether and hydroxypropyl allyl ether are preferable. The alkyl group of the hydroxyalkyl allyl ether preferably has 2 to 12 carbon atoms. From the viewpoint of polymerizability, hydroxyethyl allyl ether is more preferable. Allyl alcohol can also be preferably used.
The fluorine-based copolymer obtained by copolymerizing these hydroxyl-containing monomers can be half-esterified with an acid anhydride or the like to form a polymerized unit having a carboxyl group in the fluorine-based copolymer.

Examples of the allyl ether having an epoxy group include allyl ether having an alicyclic epoxy group such as 3-allyloxycyclohexene oxide and allyl glycidyl ether.

As the monomer giving the polymerized unit (d),
3-butenoic acid, 4-pentenoic acid, 3-hexenoic acid, 4-
Hexenoic acid, 5-hexenoic acid, 5-heptenoic acid, 6-heptenoic acid, 6-octenoic acid, 7-octenoic acid, 7-nonenoic acid, 8-nonenoic acid, 8-decenoic acid, 9-decenoic acid, 9
And unsaturated carboxylic acids such as -undecenoic acid, 10-undecenoic acid, 11-tridecenoic acid and 12-tridecenoic acid.

The monomer giving the polymerized unit (e) is one or more olefins selected from ethylene, propylene and isobutylene. The unsaturated group in the olefin is selected from those which are polymerizable unsaturated groups.

The ratio of each polymerized unit to the total of all polymerized units of the fluorocopolymer A is (a) 35 to 65 mol%,
(B) 5 to 45 mol%, (c) 1 to 30 mol%, (d)
1 to 30 mol% and (e) 0 to 40 mol%. The polymerized unit (e) is an optional component, and when the polymerized unit (e) is 0 mol%, it means that the fluorine-based copolymer A does not include this polymerized unit. The preferred ratio of each polymerized unit to the total of all polymerized units is (a) 40 to 60 mol%, (b)
10-40 mol%, (c) 5-25 mol%, (d) 5
25 mol% and (e) 1 to 30 mol%.

The weight average molecular weight of the fluorinated copolymer A in the present invention is preferably 5,000 or more, preferably 10,000 to 10,000.
More preferably, it is 300,000. If the molecular weight is too small, the weather resistance of the coating film is insufficient, and if the molecular weight is too large, the viscosity of the coating becomes too high, which is not preferable. In the present invention, the fluorine-based copolymer A is used in the presence or absence of a polymerization catalyst in a predetermined ratio of a monomer mixture, and a polymerization initiator such as a polymerization initiator or ionizing radiation is allowed to act on the copolymerization reaction. It can be manufactured by performing. Here, as the polymerization initiator, a water-soluble one or an oil-soluble one can be appropriately used depending on the polymerization type or the polymerization medium. The amount of the polymerization initiator to be used can be appropriately changed depending on the type and the copolymerization reaction conditions, but usually, the amount is 0.1 to 10% based on the total amount of the monomers to be copolymerized.
About 0.5 to 0.5% by weight is employed.

The type of the above-mentioned copolymerization reaction is not particularly limited, and bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization and the like can be employed. From the standpoint of easiness, emulsion polymerization in an aqueous medium or alcohols such as isopropyl alcohol, n-butyl alcohol, s-butyl alcohol, t-butyl alcohol, esters, and saturated halogenated carbon having one or more fluorine atoms Solution polymerization using an aromatic hydrocarbon such as hydrogen or xylene as a solvent is preferred. The polymerization temperature can be about 10 to 90 ° C. The reaction pressure can be appropriately selected, but is usually 1 to 100 kg / c.
m ² , particularly preferably about ² to 50 kg / cm ² .

The fluorinated electrodeposition coating composition of the present invention contains a fluorinated copolymer B obtained by neutralizing at least a part of the carboxyl groups of the fluorinated copolymer A with a basic compound.
Examples of the basic compound include the following.

Primary to tertiary such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, monobutylamine, dibutylamine, tributylamine, etc.
Grade alkylamines, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, alkanolamines such as dimethylaminoethanol, diethylaminoethanol, ethylenediamine, propylenediamine, diethylenetriamine, triethylenetetramine Alkylene polyamines such as ethyleneimine and propyleneimine, ammonia, piperazine, morpholine, pyrazine and pyridine.

The acid value of the fluorocopolymer B is 5 mg KOH
/ G or more. If the amount of the carboxyl group is too small, that is, if the acid value is less than 5 mgKOH / g, it is difficult to obtain an aqueous solution, and it may not be suitable for an electrodeposition paint, which is not preferable. If the acid value is too large, the alkali resistance, boiling water resistance and the like of the coating film may decrease, which is not preferable. Acid value is 5-150mgKOH
/ G is preferred, and 10-100 mgKOH / g is more preferred. When the fluorine-based copolymer B has a hydroxyl group,
The hydroxyl value of the fluorocopolymer B is 10 to 150 mg KO.
H / g is preferred, and 20-100 mgKOH / g is more preferred.

In the electrodeposition coating composition of the present invention, a polymer other than the fluorocopolymer B as a resin component for forming a coating film,
For example, a polyester polymer, an acrylic polymer, and the like may be blended, and if necessary, a curing agent, a surface smoothing agent, a silane coupling agent, an ultraviolet absorber, a light stabilizer,
Color pigments, metallic pigments, extender pigments, matting agents and the like can be blended.

As the curing agent, amino plastics, blocked isocyanate compounds and the like can be used. In particular, aminoplasts are preferably employed. As aminoplasts, melamine resin, guanamine resin, urea resin and the like can be used. In particular, among melamine resins, methylol partially etherified with at least one of lower alcohols such as methanol, ethanol, propanol and butanol. Melamine resins are preferred. The curing agent is preferably used at a ratio of about 5 to 100 parts by weight per 100 parts by weight of the fluorocopolymer B.

The electrodeposition coating composition of the present invention comprises a fluorine-containing copolymer B
Is preferably dissolved or dispersed in an aqueous medium. Here, water alone may be used as the aqueous medium, but preferably contains an organic solvent in order to enhance the stability of the composition.

The organic solvent is water-soluble for stabilizing the electrodeposition paint and has an affinity for the fluorocopolymer B, for example, methanol, ethanol, n-propanol, isopropyl alcohol, n-butyl. Alcohol, isobutyl alcohol, s-butyl alcohol, t
Alcohols such as -butyl alcohol and pentanol, and cellosolves such as methyl cellosolve, ethyl cellosolve, isopropyl cellosolve, butyl cellosolve, and s-butyl cellosolve are preferable.

The electrodeposition coating composition of the present invention is usually used by adjusting the resin solid content concentration to a range of about 3 to 50% by weight. The metal article is used as an anode in the electrodeposition paint prepared in this way, and after applying a DC voltage between the counter electrode and the metal article, the metal article is pulled up and heated and baked after washing or without washing. An electrodeposition coating film having excellent gloss is formed.

[0031]

EXAMPLES Example 1 (Synthesis of Fluorinated Copolymer A-1)
76.9 g of 2,5-norbornadiene (hereinafter referred to as NBD) in a 2.5 L stainless steel autoclave with a stirrer (withstand pressure of 50 kg / cm ² · G) and 2-hydroxyethyl allyl ether (hereinafter referred to as 2-HEAE) 56.8 g) and 10-undecenoic acid (51.2 g) were charged, and cooling air degassing and pressurization with nitrogen gas were repeated to remove dissolved air.

Next, 1129.7 g of dichloropentafluoropropane (hereinafter referred to as HCFC225) and 376.1 g of tetrafluoroethylene (hereinafter referred to as TFE).
g was introduced into the autoclave and the temperature was raised. When the temperature in the autoclave reaches 55 ° C., the pressure is 16.5 kg /
cm ² · G.

Next, 20% HCFC225 of diisopropyl peroxydicarbonate (hereinafter referred to as IPP) was used.
The reaction was started by adding 2 ml of the solution. While maintaining the pressure as the pressure decreased, 225.3 g of TFE and NBD
, 186.5 g of 2-HEAE, 36.5 g of 10-undecenoic acid, and the reaction was continued.

During the reaction, IPP 20% HCFC
A total of 30 ml of the 225 solution was added continuously. After 10 hours, the supply of each monomer was stopped, and the reaction was continued up to 2 kg / cm ² · G. Thereafter, the autoclave was cooled with water to stop the reaction.

After reaching room temperature, unreacted monomers were purged and the autoclave was opened. 4 m of the obtained polymer
The solvent was removed under reduced pressure of mHg over 5 hours to obtain a fluorine-based copolymer (hereinafter, referred to as A-1). ¹³ C of A-1
Table 1 shows the results of composition analysis and physical property measurement by -NMR.

Examples 2 to 5 (Fluorine-based copolymers A-2 to A
The synthesis was performed in the same manner as in A-1 to obtain a fluorine-based copolymer having the composition (mol%) and physical properties shown in Table 1 (hereinafter, referred to as A-2 to A-5). . CTFE in Table 1 represents chlorotrifluoroethylene.

"Examples 6 to 10 (Evaluation of electrodeposition paint)""Preparation of electrodeposition paint" Mixture of fluorinated copolymers A-1 to A-5 and melamine resin (Cymel 303, manufactured by Mitsui Cyanamid) Triethylamine was added to (fluorine-based copolymer / melamine resin = 7: 3 (weight ratio)) so as to have a neutralization ratio of 80%. Thereafter, ethylene glycol monobutyl ether was added to a solid content of 5% by weight, and ion-exchanged water was further added to prepare aqueous dispersion type electrodeposition coating compositions B-1 to B-5 having a solid content of 10% by weight.

"Electrodeposition coating" The aqueous dispersion type electrodeposition coating B-
1 to B-5 were applied to an alumite-treated aluminum plate (anode) at 180 V for 3 minutes. The obtained aluminum plate was washed with ion-exchanged water,
A curing reaction was performed for 30 minutes. Table 2 shows the evaluation results of the coated plates. Table 3 shows the evaluation method.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

The electrodeposition coating composition of the present invention has excellent liquid stability.
Further, the obtained coating film has an excellent appearance, has high hardness for improving the scratch resistance of the coating film surface, and also has excellent properties such as adhesion and weather resistance.

Claims (3)

[Claims] (1) a polymerization unit based on a fluoroolefin, (b) a polymerization unit based on a cyclic monomer having an unsaturated group in a ring copolymerizable with the fluoroolefin,
(C) a polymerized unit based on an allyl ether having a curable site, an olefin having a curable site or allyl alcohol, (d) a polymerized unit having a carboxyl group,
And optionally (e) polymerized units based on one or more olefins selected from ethylene, propylene and isobutylene, wherein the ratio of each polymerized unit to the total of all polymerized units is (a) 35 to 65 mol%, (b) 5 to 45 mol%, (c) 1 to 30 mol%, (d) 1 to 30 mol% and (e) at least a part of the carboxyl groups of the fluorocopolymer having a carboxyl group having 0 to 40 mol%. A fluorine-based electrodeposition coating material containing a fluorine-based copolymer obtained by neutralizing the above with a basic compound. 2. The fluorine-based electrodeposition coating composition according to claim 1, wherein the ring of the cyclic monomer is an aliphatic ring or a heterocyclic ring. 3. The fluorine-based electrodeposition coating composition according to claim 1, wherein the cyclic monomer is a norbornadiene or a norbornene.