JP4666126B2 - Aqueous resin composition - Google Patents

Description

【００３２】
【表２】

【００３３】
【発明の効果】
本発明の水性樹脂組成物は、耐候性に優れた塗膜を形成できるとともに、塗膜面が短時間で乾燥する。また、本発明の水性樹脂組成物は、低温での造膜性に優れた塗料とすることができ、屋外用の上塗り塗料として極めて有用である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aqueous resin composition containing a fluoropolymer.
[0002]
[Prior art]
Since the aqueous resin composition of a fluoropolymer can form a coating film having excellent weather resistance, chemical resistance and the like, it is used as a protective coating material for top coating in outdoor coating. In particular, in the case of outdoor construction, it is required that the coating surface be dried in a short time after painting. In order to dry the coating surface in a short time, there is a method using a polymer having a high glass transition temperature. However, a coating using such a polymer has a low film-forming property at low temperatures, and is used in winter. In coating, problems such as cracking of the coating film are likely to occur. On the other hand, in coatings using polymers having a high glass transition temperature, there is a method of adding a large amount of a film-forming aid in order to improve the film-forming property at a low temperature. Since it is a boiling point, it becomes difficult to dry a coating-film surface in a short time. Furthermore, there is a method of using a large amount of a low boiling point solvent as a film forming aid, but in this case, there is a problem that the gloss of the coating film is lowered.
[0003]
[Problems to be solved by the invention]
The object of the present invention is to solve the above-mentioned problems of the prior art and to form a coating film that can dry the coating surface in a short time, improve the film-forming property at low temperature, and has excellent weather resistance. It is in providing the aqueous resin composition which can be performed.
[0004]
[Means for Solving the Problems]
In the present invention, dispersed particles (A) of a polymer (a) having a glass transition temperature of 40 ° C. or higher and dispersed particles (B) of a polymer (b) having a glass transition temperature of 30 ° C. or lower in an aqueous medium. An aqueous resin composition containing, wherein the polymer (a) contains a fluoroolefin polymer, and the average particle size of the dispersed particles (A) is 1 / 1.5 or less of the average particle size of the dispersed particles (B). der is, and the dispersed particles (a) is, is an aqueous resin composition characterized in that it is contained 5-50% by weight relative to the total amount of the dispersed particles (a) and the dispersed particles (B) .
[0005]
In the present invention, the polymer (a) includes a fluoropolymer. When the polymer (a) contains a fluoropolymer, a coating film having excellent weather resistance can be formed. The fluorine-containing polymer is a polymer obtained by polymerizing fluorine-containing monomers. Examples of fluorine-containing monomers include fluoroolefins such as tetrafluoroethylene, vinylidene fluoride, chlorotrifluoroethylene, hexafluoropropylene, ester compounds of alcohols having a polyfluoroalkyl group and (meth) acrylic acid, fluorinated alkylene oxides, etc. Is exemplified. In particular, a fluoroolefin having a fluorine atom directly bonded to a polymer main chain carbon atom and giving a polymer having no ether bond in the main chain structure is preferable because a coating film having excellent durability can be formed. From the viewpoint of durability, the copolymerization ratio of the fluoroolefin is preferably 30 mol% or more, particularly 50 mol% or more.
[0006]
Further, the fluorine-containing polymer may be a polymer composed only of the above-mentioned fluorine-containing monomer, or may be a copolymer with another monomer. Examples of other monomers include vinyl ethers, carboxylic acid vinyl esters, carboxylic acid allyl esters, (meth) acrylic acid, (meth) acrylic acid esters, and the like. By copolymerizing these monomers, functions such as dispersion stability of the fluoropolymer in an aqueous medium and adhesion to a substrate can be enhanced.
[0007]
The dispersed particles (A) may be single particles of a fluorine-containing polymer as described above, or may be composite particles of different types of fluorine-containing polymers or composite particles of a fluorine-containing polymer and another polymer. There may be. The composite particles can be synthesized by a method such as forming another polymer in an aqueous dispersion of one dispersed particle. As the other polymer, a polymer having (meth) acrylic acid ester as a main component is preferable from the viewpoint of compatibility with a fluorinated polymer. Further, by using a monomer having a carboxyl group as a copolymerization monomer, the dispersion stability of the resin particles can be improved, and the effect of the associative thickener usually added to the paint can be improved. . By using a monomer having a polyoxyethylene chain, the dispersion stability of the resin particles can be improved. By using a (meth) acrylic acid ester having a hydroxycyclohexyl group, the water resistance of the coating film can be improved. By copolymerizing a monomer having a structure such as hindered amine, benzotriazole, or benzophenone, the weather resistance of the coating film can be further improved.
[0008]
The polymer (b) may not contain a fluorinated polymer, but the weather resistance of the coating film can be further improved by including the fluorinated polymer. Therefore, the polymer (b) in the present invention preferably contains a fluoropolymer. Examples of the polymer (b) include polymers having (meth) acrylic acid ester as a main component, in addition to those described for the polymer (a).
[0009]
The dispersed particles (B) may be single particles of a fluorine-containing polymer as described above, or composite particles of different types of fluorine-containing polymers or composite particles of a fluorine-containing polymer and another polymer. There may be. The composite particles can be synthesized by a method such as forming another polymer in an aqueous dispersion of one dispersed particle. As the other polymer, a polymer having (meth) acrylic acid ester as a main component is preferable from the viewpoint of compatibility with a fluorinated polymer.
[0010]
Further, when at least one of the polymers constituting the dispersed particles (A) and / or the dispersed particles (B) has a crosslinkable functional group, it can be crosslinked to form a tougher coating film. Examples of the crosslinkable functional group include a hydroxyl group, a carboxyl group, a carbonyl group, an epoxy group, a hydrazino group, and an alkoxysilyl group. The crosslinkable functional group can be introduced by copolymerizing a monomer having a crosslinkable functional group. As monomers having a crosslinkable functional group, hydroxyl group-containing monomers such as hydroxyalkyl vinyl ether, hydroxyalkyl allyl ether, hydroxyalkyl (meth) acrylate and diacetone acrylamide, carboxyl group-containing monomers such as (meth) acrylic acid and undecylenic acid, Examples thereof include epoxy group-containing monomers such as glycidyl vinyl ale, glycidyl allyl ether, and glycidyl (meth) acrylate.
[0011]
In addition, as a curing agent for crosslinking the polymer having the crosslinkable functional group introduced therein, a polyisocyanate compound or a blocked product thereof, a polyvalent epoxy compound, an oxazoline derivative, a hydrazine derivative, a polyvalent amine compound, a polyvalent carbonyl compound, etc. Is exemplified.
[0012]
In the present invention, the average particle size of the dispersed particles (A) is preferably 30 to 700 nm, and the average particle size of the dispersed particles (B) is preferably 45 to 1050 nm. If the average particle size is too small, the viscosity of the aqueous resin composition increases, and the resin concentration of the paint adjusted to a viscosity that is easy to paint decreases. On the other hand, if the average particle size is too large, the film-forming property at low temperatures may be lowered, and the water resistance of the coating film may be lowered. More preferable average particle diameters are 50 to 350 nm for dispersed particles (A) and 100 to 700 nm for dispersed particles (B).
[0013]
In the present invention, the average particle diameter is measured by various methods such as a static light scattering method, a dynamic light scattering method, a natural precipitation method, an electrophoretic light scattering method, and a direct observation method using a microscope. The average particle diameters of the dispersed particles (A) and the dispersed particles (B) are desirably measured and compared using the same principle method or the same apparatus. In the specific example of this invention, it showed with the numerical value measured using Otsuka Electronics ELS-800 (brand name). The glass transition temperature was measured by DSC.
[0014]
In the present invention, the glass transition temperature of the polymer (a) is 35 ° C. or higher, and the glass transition temperature of the polymer (b) is lower than 35 ° C. When the glass transition temperature of the polymer (a) is too low, the drying property of the coating film surface is lowered. The glass transition temperature of the polymer (a) is preferably 40 ° C. or higher. If the glass transition temperature of the polymer (b) is too high, the film-forming property at low temperatures is lowered. The glass transition temperature of the polymer (b) is preferably 30 ° C. or lower. The glass transition temperature of the polymer can be adjusted by selecting a copolymerization monomer or by crosslinking the polymer.
[0015]
In the present invention, the average particle size of the dispersed particles (A) is 1.5 times or less, preferably 1/2 or less, of the average particle size of the dispersed particles (B). Since the average particle size of the dispersed particles (A) is smaller than the average particle size of the dispersed particles (B), the coating film formed by drying has a large proportion of the dispersed particles (A) in the coating film surface. Therefore, it is considered that the performance of the dispersed particles (A) greatly affects the performance of the coating film surface.
[0016]
The ratio of the dispersed particles (A) is preferably 5 to 50% on a mass basis with respect to the total amount of the dispersed particles (A) and the dispersed particles (B). If the amount of the dispersed particles (A) is too large, the film-forming property at a low temperature is lowered. If the amount of the dispersed particles (A) is too small, sufficient dry curability cannot be achieved. Preferably it is 10 to 40% of range.
[0017]
The aqueous resin composition of the present invention includes dispersed particles (A) and dispersed particles (B). The total content of the dispersed particles (A) and dispersed particles (B) is based on the entire dispersed particles contained. 80% or more is preferable on a mass basis, and particularly 90% or more is preferable. Usually, the total content of the dispersed particles (A) and the dispersed particles (B) is 100% on a mass basis with respect to the entire dispersed particles contained.
[0018]
The aqueous resin composition of the present invention can be used for paints by adding various additives usually used as paint additives. Examples of such additives include pigments, pigment dispersants, wetting agents, antifoaming agents, leveling agents, film-forming aids, thickeners, preservatives, ultraviolet absorbers, light stabilizers, antioxidants, and the like. The
[0019]
Since the coating material using the aqueous resin composition of the present invention can form a coating film excellent in weather resistance, it is useful as a top coating material for outdoor use. The paint can be applied by a painting method such as a brush, a roller, or a spray. Also, inorganic base materials such as concrete, natural stone and glass, metal base materials such as iron, stainless steel, aluminum, copper, brass and titanium, organic base materials such as acrylic resin, polycarbonate resin, FRP and resin reinforced concrete It can be applied to a material or the like with or without an undercoat.
[0020]
【Example】
[Example 1]
Chlorotrifluoroethylene (CTFE) / ethyl vinyl ether (EVE) / cyclohexyl vinyl ether (CHVE) / 4-hydroxybutyl vinyl ether (HBVE) / HBVE compound with an average of 10 molecules of ethylene oxide (EOVE) is 50/15/37 / An aqueous dispersion (X1) containing a polymer copolymerized at a ratio of 1.5 / 1.5 (mol%) was used. The aqueous polymer dispersion (X1) contained dispersed particles having an average particle diameter of 100 nm, and the solid content concentration was 50% (mass basis; the same applies hereinafter). The glass transition temperature of the polymer measured by DSC was 45 ° C.
[0021]
[Example 2]
In stainless steel autoclave, 1000 g of deionized water, 10 g of EVE, 240 g of CHVE, 20 g of HBVE, 10 g of a compound obtained by adding ethylene oxide on average to 1-hydroxymethyl-6-vinyloxymethylcyclohexane (EOVCH), After charging 25 g of a compound (EOLA) with an average of 10 moles of ethylene oxide added to lauryl alcohol and 2 g of sodium lauryl sulfate, deoxygenated after stirring, 500 g of CTFE was added, the temperature was raised to 60 ° C., and an aqueous ammonium persulfate solution was added. The polymerization reaction was initiated by addition. The difference between the external temperature and the internal temperature was kept at 5 ° C. or less, and the addition of the ammonium persulfate aqueous solution was continued, and the polymerization reaction was completed in 20 hours.
The obtained polymer aqueous dispersion (X2) contained dispersed particles having an average particle diameter of 70 nm, the solid content concentration was 47%, and the glass transition temperature of the polymer measured by DSC was 54 ° C.
[0022]
[Example 3]
A stainless steel autoclave was charged with 1000 g of deionized water, 240 g of EVE, 10 g of CHVE, 20 g of HBVE, 10 g of EOVCH, 25 g of EOLA, and 2 g of sodium lauryl sulfate. 500 g was added, the temperature was raised to 70 ° C., and an aqueous ammonium persulfate solution was added to initiate the polymerization reaction. The difference between the external temperature and the internal temperature was kept at 5 ° C. or less, and the addition of the ammonium persulfate aqueous solution was continued, and the polymerization reaction was completed in 20 hours.
The obtained polymer aqueous dispersion (X3) contained dispersed particles having an average particle diameter of 80 nm, the solid content concentration was 46%, and the glass transition temperature of the polymer measured by DSC was 7 ° C.
[0023]
[Example 4]
A stainless steel autoclave was charged with 1000 g of deionized water, 200 g of EVE, 50 g of CHVE, 20 g of HBVE, 10 g of EOVCH, 25 g of EOLA, and 0.5 g of sodium lauryl sulfate. 500 g of CTFE was added, the temperature was raised to 70 ° C., and an aqueous ammonium persulfate solution was added to initiate the polymerization reaction. The difference between the external temperature and the internal temperature was kept at 5 ° C. or less, and the addition of the ammonium persulfate aqueous solution was continued, and the polymerization reaction was completed in 20 hours.
The obtained polymer aqueous dispersion (X4) contained dispersed particles having an average particle diameter of 340 nm, the solid content concentration was 46%, and the glass transition temperature of the polymer measured by DSC was 11 ° C.
[0024]
[Example 5]
A glass reactor was charged with 600 g of deionized water and heated to 60 ° C. Here, 1000 g of a monomer mixture (tert-butyl methacrylate / n-butyl methacrylate / 2-ethylhexyl methacrylate / methacrylic acid = 34/25/40/1 (mass ratio)) and ABEX23S (trade name: Rhodia Nikkasha) 15 g of a surfactant (manufactured) was added and stirred. Further, 400 g of deionized water was added and stirred uniformly to obtain a pre-emulsion.
50 g of this pre-emulsion was placed in a glass reactor and heated to 80 ° C.
While stirring, 50 g of a 2% aqueous solution of sodium persulfate was added and stirring was continued for 1 hour. Thereafter, 1965 g of the pre-emulsion and 20 g of 2% aqueous solution of sodium persulfate were added over 5 hours, and stirring was further continued for 3 hours. The internal temperature was cooled to 20 ° C., stirring was stopped, and the aqueous polymer dispersion was taken out. 28% aqueous ammonia was added to obtain an aqueous polymer dispersion (X5) having a pH of 9. The obtained polymer aqueous dispersion (X5) contained dispersed particles having an average particle diameter of 230 nm, had a solid content concentration of 45%, and had a glass transition temperature of 5 ° C. as measured by DSC.
[0025]
[Example 6]
A stainless steel autoclave was charged with 1000 g of deionized water, 10 g of EVE, 240 g of CHVE, 20 g of HBVE, 10 g of EOVCH, 25 g of EOLA, and 0.5 g of sodium lauryl sulfate. 500 g of CTFE was added, the temperature was raised to 70 ° C., and an aqueous ammonium persulfate solution was added to initiate the polymerization reaction. The difference between the external temperature and the internal temperature was kept at 5 ° C. or less, and the addition of the ammonium persulfate aqueous solution was continued, and the polymerization reaction was completed in 20 hours.
The obtained polymer aqueous dispersion (X6) contained dispersed particles having an average particle diameter of 350 nm, the solid content concentration was 49%, and the glass transition temperature of the polymer measured by DSC was 56 ° C.
[0026]
[Examples 7 to 18]
Polymer dispersions X1 to X6 shown in Table 1 were mixed at a mass ratio shown in Table 1 to prepare an aqueous resin composition. 100 g of the aqueous resin composition, 25 g of Type C CR-97 (trade name: Titanium Oxide manufactured by Ishihara Sangyo Co., Ltd.), 4 g of ethylene glycol monobutyl ether acetate, SN Disapersant 5027 (trade name: Pigment dispersant manufactured by San Nopco) Of FS Antifoam 90 (Dow Corning antifoaming agent), BERMODOL PUR2102 (AKZO NOBEL thickening agent), and deionized water 15 g. A white paint was obtained.
[0027]
Each paint was applied to a slate plate coated with Bonflon water-based primer S clear (trade name: Primer manufactured by Asahi Glass Coat and Resin Co., Ltd.) so as to have a coating amount of 150 g / m ² , and the following tests were conducted. The results are shown in Table 2.
[0028]
Surface drying property: According to JIS K5600-3-2, the time until the coating film was determined to be surface drying was measured. In Table 2,> 8 indicates that the coating film was not determined to be surface dried even after 8 hours. The coating was cured at 23 ° C. and 50%.
[0029]
Low-temperature film-forming property: The substrate and paint were allowed to stand at 5 ° C. for 10 hours and then applied, immediately put in a 5 ° C. thermostat and dried for 5 hours. After drying, the coated plate was immersed in deionized water and left at room temperature for 1 hour. After standing, it was lifted from deionized water and dried at 23 ° C. and 50%. The case where no abnormality of the coating film was observed after pulling up and after drying was rated as ◯, and the case where blistering was observed on the entire surface during lifting or cracking after drying was marked as x.
[0030]
Weather resistance: JIS K5400 9.8.1 Sunshine carbon arc lamp type accelerated weather resistance test was used to measure the 60-degree specular gloss before and after the 5000 hour test, and the residual gloss ratio (gloss after test ÷ gloss before test x 100) was calculated.
[0031]
[Table 1]

[0032]
[Table 2]

[0033]
【The invention's effect】
The aqueous resin composition of the present invention can form a coating film excellent in weather resistance, and the coating film surface dries in a short time. In addition, the aqueous resin composition of the present invention can be used as a coating having excellent film-forming properties at low temperatures, and is extremely useful as an outdoor top coating.

Claims (5)

An aqueous resin composition comprising, in an aqueous medium, dispersed particles (A) of a polymer (a) having a glass transition temperature of 40 ° C. or higher and dispersed particles (B) of a polymer (b) having a glass transition temperature of 30 ° C. or lower. A thing,
The polymer (a) includes a fluoroolefin polymer ,
The average particle size of the dispersed particles (A) Ri Average der 1 following 1.5 minutes in the particle size of the dispersed particles (B), and,
The aqueous resin composition, wherein the dispersed particles (A) are contained in an amount of 5 to 50% on a mass basis with respect to the total amount of the dispersed particles (A) and the dispersed particles (B) .   The aqueous resin composition according to claim 1, wherein the polymer (b) contains a fluoropolymer.   The aqueous resin composition according to claim 2, wherein the fluorinated polymer is a fluoroolefin polymer. The aqueous resin composition according to claim 1, 2, or 3 , wherein the total content of the dispersed particles (A) and the dispersed particles (B) is 80% or more based on the weight of the entire dispersed particles contained. The coating material formed by adding the compounding agent for coating materials to the aqueous resin composition in any one of Claims 1-4 .