JPS62158766A - Aqueous dispersin containing fluorocopolymer - Google Patents

Abstract

PURPOSE:To provide the titled dispersion which has excellent dispesion stability and gives a coating film having excellent weather resistance and durability, containing a specified random fluorocopolymer and a water-soluble resin. CONSTITUTION:80-20pts.wt. random fluorocopolymer (A) which has an OH value of 20-200, an acid value of 3-10 and solubility in org. solvents at room temp. and is composed of a fluoroolefin, cyclohexylvinyl ether, etc. and 20-80 pts.wt. random fluorocopolymer (B) having a carboxyl, sulfo, phosphate, hydroxyl, amino or isocyanate groups as functional groups capable of forming a three- dimensional crosslinked structure and a solubility parameter of form 10.5 to a valve obtd. by adding 2.2 to the solubility parameter of the component A (e.g., an acrylic resin or a urethane resin) are dispersed in water to obtain the titled dispersion.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a fluorine-containing aqueous dispersion and an aqueous coating composition obtained therefrom.

(Prior art and its problems) Organic solvent-based paints use volatile organic solvents, so they have an impact on the human body and safety and health problems such as explosions and fires.
Furthermore, there are problems with pollution due to air pollution, etc. Furthermore, from the viewpoint of resource saving, the use of organic solvent-based paints containing a large amount of the above-mentioned organic solvents has become a problem. Therefore, conversion from organic solvent-based paints to water-based paints using water as a medium is being actively carried out.

Water-based paints are obtained by using a water-soluble resin vehicle and dispersing it in an aqueous medium, but in many cases, in order to dissolve or disperse the resin in water, a large amount of acidic functional groups (e.g. It is generally adopted to introduce a carboxyl group or a sulfonic acid group. Therefore, even if a coating film is formed, this acidic functional group tends to remain in the coating film.Since acidic functional groups are generally hydrophilic, the water resistance of the coating film formed is poor, and the coating film lasts for a long time. There is a problem that the durability and weather resistance are inferior. In order to solve this problem, attempts have been made to water-disperse fluororesins with good weather resistance.

Although emulsification using a surfactant may be considered to disperse the fluororesin in water, emulsification using a surfactant is insufficient in terms of water resistance.

Technologies for blending fluorine-containing resins for the purpose of improving durability include a combination of a fluorine-containing copolymer and an epoxy resin (Japanese Patent Application Laid-Open No. 55-25416) and a combination of a fluorine-containing copolymer and an acrylic resin. Combination (JP-A-55-2
No. 5417), but all of these are basically solvent-based.

JP-A-59-15715 and JP-A-52-58
No. 733 discloses an aqueous acrylic resin dispersion of polyvinylidene fluoride, but these compositions cannot achieve both durability and gloss.

OBJECTS OF THE INVENTION Therefore, there is a need to obtain a water-based resin dispersion using a fluorine-containing copolymer to obtain a water-based coating composition that is durable and weather resistant.

(Structure of the Invention) In view of the above points, the present invention provides a copolymer containing 80 to 20 parts by weight of a fluorine-containing random copolymer (A) having a hydroxyl group in the molecule and 20 to 80 parts by weight of a water-soluble resin (B). A fluorine aqueous dispersion in which the aqueous resin (B) has a solubility parameter (δsp[B) of 10.5 or more and the fluorine-containing random copolymer (A) has a solubility parameter δsp[A]
) A fluorine-containing aqueous dispersion having a value of 2.2 or less.

A typical example of the fluorine-containing random copolymer used in the present invention is a fluorine-containing random copolymer containing a fluoroolefin, cyclohexyl vinyl ether, alkyl vinyl ether, etc. as a constituent, as disclosed in JP-A-57-34107. It is a polymer and is soluble in many organic solvents at room temperature. This type of polymer is commercially available from Asahi Glass Co., Ltd. under the trade name "Lumiflon".

The fluorine-containing random copolymer has a hydroxyl value of 20-200 and an acid value of 3-! Preferably, it has 0. If the hydroxyl value is less than 20, the stability of the crosslinked product and the dispersion will deteriorate. Furthermore, if the hydroxyl value exceeds 200, water resistance and durability will not be sufficient. Acid value is 2-20, preferably 3-10
If the range is exceeded, the stability of the dispersion will deteriorate.

The aqueous resin (B) used in the present invention includes a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a hydroxyl group, an oxirane group, an active methylol group, an amino group, and a reactive carbon group as functional groups capable of forming a three-dimensional crosslinked structure. It may contain a carbon unsaturated group, an isocyanate group or a blotted 4-isocyanate group, a halogen group, etc., and if necessary, it itself may contain a functional group for waterification (for example, a carboxylic acid group, a sulfonic acid group, a hydroxyl group). , amino groups), and the types of resins include, for example, alkyd type, polyester type, maleated part type, maleated polyalkadiene type, epoxy type, acrylic type, urethane type, polyamide type, polyethylene imine type. and aminoplast type.

Introduction of functional groups into the resin may be carried out according to general methods, and may be carried out by selecting monomers and controlling the polymerization reaction.

Specifically, in the case of alkyd type and polyester type □, a carboxyl group may be introduced in the reaction step of a polybasic acid and a polyhydric alcohol to form an aqueous resin. In the case of maleated oils, carboxyl groups can be introduced into aqueous resins by treating drying oils (eg, linseed oil, dehydrated castor oil, soybean oil, Kiriura) with maleic anhydride. Maleated polyalkadienes include, for example, polybutadiene (eg, 1,2-polybutadiene, 1,4-polybutadiene, 1,2- and 1.2-polybutadiene).
4-copolymerized polybutadiene), polyisoprene or polycyclopentanene, for example by adding an unsaturated carboxylic acid (e.g. maleic anhydride, hymic anhydride, fumaric acid, itaconic acid) to its double bond. It may be one in which a carboxyl group is introduced to become an aqueous resin. In the epoxy system, in addition to various epoxy resins typified by the reaction of bisphenol A and shrimp chlorohydrin, various other compounds having epoxy groups can be used. These may be used as they are if they are originally water-soluble, or may be made water-soluble or water-dispersible by introducing a basic group or an acidic group into some or all of the oxirane groups. For acrylic, α,
β-unsaturated carboxylic acids (e.g. acrylic acid, methacrylic acid, cinnamic acid, crotonic acid, fumaric acid, citraconic acid,
maleic anhydride) and acrylic esters (e.g. methyl ester, ethyl ester, propyl ester, butyl ester, 2-ethylhexyl ester, lauryl ester) and/or methacrylic esters (e.g. methyl ester, ethyl ester, propyl ester, butyl ester) ester, 2-ethylhexyl ester, lauryl ester), and if necessary, an aqueous resin obtained by polymerizing other polymerizable monomers.

In the case of urethane, diisocyanate compounds (for example, hexamethylene diisocyanate, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), isophorone diisocyanate) and active hydrogen compounds. Examples include resins having a skeleton structure of and into which a water-soluble group is introduced. For polyamides, dicarboxylic acids (e.g. phthalic acid, adipic acid, sebacic acid, dimeric fatty acids) and polyamines (e.g. ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenediamine, propylenediamine, butylenediamine) are used. Amino group-containing polymers obtained by condensation are preferred, and polyamides obtained by further condensing oligomers obtained by ring-opening polymerization of lactams (e.g., ε-caprolactam) with the above polyamines, or instead of the above polyamines, are preferred. Polyesteramides obtained using alkanolamines (eg, ethanolamine, propatoolamine) can be used as aqueous resins.

What is polyethyleneimine? Pregnancy←Cl! -C11, -N→
It is a straight-chain or branched-chain resin in which i is a basic repeating unit, and can be synthesized by known techniques. In addition,
In some cases, ionene-type resins can also be used, for example, polymers produced by the Menschudkin reaction of polyamines (preferably diamines) and polyhalides (preferably dihalides) T: [(-N(RlX
Rt)R+] (an integer from 3 to 1000) as a basic repeating unit, and can be synthesized according to known techniques.In the aminoplast system, melamine resins, urea resins, etc., which are known as water-soluble or hydrophilic resins, are used. It is ok to use the one that is provided.

For the above aqueous resins, the resin having acidic groups such as carboxyl groups can be made aqueous by converting the acidic groups into bases (
For example, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, diethylenetriamine, triethylenetetramine, monoethanolamine, jetanolamine, triethanolamine, monoisopropanolamine, diisopropylamine, It may be neutralized with (patulamine, dimethylethanolamine, morpholine, methylmorpholine, piperazine, ammonia, sodium hydroxide, potassium hydroxide, lithium hydroxide). On the other hand, when aqueousizing a resin having a basic group such as an amine group, the basic group is removed using an acid (e.g., hydrochloric acid, sulfuric acid, oxalic acid, acetic acid, formic acid, lactic acid).
You can neutralize it with

In the present invention, the solubility parameter (δsp[B]) h<10 of the aqueous resin (B) is 5 or more, and the δsp[A] value of the fluorine-containing random copolymer (A) is 2.
It must be less than or equal to the sum of 2. The solubility parameter (δsp) was determined by Su and Kolpet (K, W, S
Uh.

J.M. Corbett) Journal of
Applied Polymer Science (Journal)
of A11lplied Polymer 5cie
nce), 12.2359 (1968).

, δsp=σrtoδm(l+fVgo・δm b )/(
, /T7+ /V'1E) (where mQ is a low sp solvent,
mh is the high sp solvent, δ is the solubility parameter and V is the molecular volume at the point. ) When δsp[B] is smaller than 10.5, the water solubility of the aqueous resin deteriorates, and the stability of the dispersion system deteriorates.

δsp[B] is δsp[A]+ 2 of the fluororesin,
When it is larger than 2, the compatibility with the fluororesin deteriorates, and dispersion stability becomes a problem. Moreover, the gloss of the coating film becomes poor.

According to the present invention, an aqueous dispersion is obtained by dispersing the resin components (A) and (B) in water. This dispersion may be further formulated with pigments and additives (eg, dispersants, flow control agents, UV protection agents) to form aqueous coating compositions. The aqueous coating composition may also include a curing agent. Examples of curing agents include melamine resin, polyvalent metal salts (e.g. cobalt naphthenate, lead naphthenate, zinc naphthenate), triglycidylison anurate (TF
IC), dicyandiamide, blocked isocyanate, and the like.

The blending ratio of the fluorine-containing random copolymer and water-soluble resin is preferably 20/80 to 80/20. If it is smaller than 20780, effects such as durability cannot be obtained by blending the fluorine-containing random copolymer. If it is larger than 80/20, problems will arise in the stability of the dispersion system.

The aqueous coating composition described above can be used in various fields such as top dust coating for automobiles and electrodeposition coating for aluminum sash.

(Effects of the Invention) The fluororesin-containing aqueous dispersion obtained by the present invention and the aqueous coating composition obtained therefrom have good dispersion stability, and the obtained coating has high weather resistance and durability, and is useful in various fields. It can be applied.

The present invention will be explained in more detail with reference to Examples.

(Example) Production Example 1 Parts by weight Styrene 16 Methyl methacrylate 14.3 Lauryl methacrylate 48.3 Hydroxyethyl acrylate 12.2 Methacrylic acid
9.2 Charge 165 g of diethylene glycol monobutyl ether into an IQ sepaul colben equipped with a reflux condenser, dropping funnel, thermometer and stirrer, and add 120 g of diethylene glycol monobutyl ether.
After raising the temperature to ℃, while maintaining that temperature, styrene 8
8g1 methyl methacrylate 78.7g, lauryl methacrylate 265.7g, hydroxyethyl acrylate 67
．． 1g, methacrylic acid 50.6g.

A mixed solution of 27.5 g of tert-butyl peroxy-2-ethylhexanoate was added dropwise over 3 hours, and after completion of the dropwise addition, after holding for 30 minutes, 1 g of diethylene glycol monobutyl ether I, tert-butyl peroxy-2-ethyl hexanoate A solution containing 2.2 g of noate was added, and the mixture was maintained for an additional 1.5 hours to complete the reaction.

The resulting aqueous acrylic resin had a resin solid content of 77% and an acid value of 6.
0, hydroxyl value 58, δsp[B] was 10.4.

Production example 2 Ingredients: 1 weight
16 Methyl methacrylate 21.7 2-ethylhexyl acrylate 38.3 Hydroquinethyl acrylate 1.1.8 Methacrylic acid
9.2 Synthesis was carried out in the same manner as in Production Example 1 except for changing the formulation.

The resulting aqueous acrylic resin had a resin solid content of 77% and an acid value of 6.
0, the hydroxyl value was 72, and the δsp[B] was 11.0.

Production Example 3 rLi ifi part Sutyrene 16 Methyl methacrylate 36.4 2-ethylhexyl acrylate 20.9 Hydroquinethyl acrylate 1785 Methacrylic acid
9.2 Produced in the same manner as in Production Example 1 except for using the above recipe.

The resulting aqueous acrylic resin had a resin solid content of 77% and an acid value of 6.
0, hydroxyl value was 85, and δsp[B] was 11.5.

Production Example 4 An emulsion was synthesized using the same ingredients as Production Example 2 as follows.

Equipped with reflux condenser, dropping funnel, thermometer and stirrer.
350 g of deionized water and 2.8 g of sodium lauryl sulfate were placed in a separable container I2, and the temperature was raised to 80°C. While maintaining the temperature, 44.8 g of styrene was added.
, 60.8 g of methyl methacrylate.

2-edylhexyl acrylate t07.2g, hydroxyethyl acrylate 41.4g, methacrylic acid 25.8g
g mixed solution and 70 g of deionized water 1 potassium persulfate 1
．． 7 g of the mixed solution was added dropwise over 2 hours, and after the addition was completed, the reaction was maintained for 2 hours to complete the reaction.

The resulting aqueous acrylic emulsion resin has a resin solid content of 4
0%, acid value 60, hydroxyl value 72, and δsp 11.0.

Group 1 Carp Using the above aqueous resin varnish, the aqueous resin varnish was combined with a fluorine-containing random copolymer shown in Table 1 below to obtain a fluororesin aqueous dispersion.

Table 1 The above water-soluble varnish is 100% neutralized with DMEA (dimethylethanolamine), and the above fluorine-containing random copolymer is added thereto and stirred until uniform. A predetermined amount of deionized water was added while stirring to obtain an aqueous fluororesin dispersion (non-volatile content: 20%).

The stability over time and particle size of this dispersion were evaluated.

The results are shown in Table-2.

Claims (1)

[Scope of Claims] 1. 80 to 20 parts by weight of a fluorine-containing random copolymer (A) having a hydroxyl group in the molecule and 20 to 20 parts by weight of a water-soluble resin (B)
A fluorine-containing aqueous dispersion containing 80 parts by weight, the solubility parameter (δsp[B]) of the aqueous resin (B)
10.5 or more and less than or equal to the solubility parameter δsp[A] value of the fluorine-containing random copolymer (A) plus 2.2. 2. The fluorine-containing random copolymer (A) has a hydroxyl value of 20 to
200 and an acid value of 3 to 10. 3. The fluorine-containing aqueous dispersion according to item 1, wherein the water-soluble resin (B) is an acrylic resin, a polyester resin, an alkyd resin, a mylenated oil, a mylenated polyalkadiene resin, an epoxy resin, or a urethane resin.