JPS63297466A - Polymer composition for urethane coating - Google Patents

Abstract

PURPOSE:To obtain the titled composition, consisting of a polymer composition prepared by reacting a polyester polymer with an acrylic polymer and a curing agent which is an isocyanate compound and capable of providing films having quick-drying property, hardness, weather and fouling resistance. CONSTITUTION:The aimed composition consisting of (A) a polymer composition, prepared by mutually reacting 5-95pts.wt. polyester polymer having 5-200 KOH mg/g, preferably 20-150 KOH mg/g hydroxyl value (preferably 500-10,000 number-average molecular weight) with 95-5pts.wt. acrylic polymer having 5-200 KOH mg/g, preferably 20-150 KOH mg/g hydroxyl value (preferably 500-20,000 number-average molecular weight) and capable of forming a homogeneous solution in dissolving in a solvent and (B) a curing agent which is an isocyanate compound (e.g. tolylene diisocyanate).

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention focuses on pigment dispersibility, which is a characteristic of polyester resin,
The present invention relates to a urethane paint composition that provides an excellent coating film that combines flexibility with the characteristics of acrylic resins, such as quick drying, hardness, weather resistance, and stain resistance.

(Prior Art and Problems) In the paint industry, there is a demand for paints that cure at room temperature or at low temperatures from the viewpoint of energy conservation.

Conventionally, urethane paints made of acrylic resin and isocyanate compounds have been commonly used for applications requiring weather resistance, and their performance levels have generally been satisfactory in terms of drying properties, hardness, and stain resistance. However, acrylic resins have a drawback in that they have poor dispersibility for pigments with high oil absorption such as carbon black and organic pigments, and problems such as pigment dispersion are likely to occur during storage, for example. In addition, in applications that require flexibility, there are examples of acrylic resins being designed to have a low glass transition point (for example, around 0°C); becomes defective, and it is difficult to maintain a balance between the two.

On the other hand, urethane paints made of polyester resins and isocyanate compounds have satisfactory performance in terms of pigment dispersion and flexibility, but drying is slow (and weather resistance and stain resistance are poorer than acrylic resin-based paints).

The object of the present invention is to provide a urethane paint free from such drawbacks.

(Means for Solving the Problems) As a result of intensive study by the present inventors on a hybrid resin composition of both polyester and acrylic paints, which takes advantage of the excellent features of both paints, the present inventors have discovered that they can cause both resins to react with each other. The present invention was achieved by discovering that a resin composition that forms a uniform solution even when dissolved in a solvent can be obtained by this method, and that a urethane coating that has both the excellent features of both systems can thereby be obtained.

That is, in the present invention, the hydroxyl value is 5 to 200 KOHmg/
g of polyester resin 5 to 95 parts by weight and a hydroxyl value of 5 to 95 parts by weight
It is characterized by consisting of a resin composition (A) that reacts with 95 to 5 parts by weight of acrylic resin of 200KOR+eg/g to form a uniform solution when dissolved in a solvent, and a curing agent (B) that is an isocyanate compound. This is a resin composition for urethane paint.

The polyester resin used in the present invention needs to have a hydroxyl value of 5 to 200 KOH-g/g, and 2
Preferably, it is from 0 to 150 KOHmg/g. If the hydroxyl value is less than 5 KOH*g/g, the reaction with the acrylic resin will not proceed sufficiently, resulting in poor compatibility, resulting in cloudy resin solution and phase separation. In addition, if the hydroxyl value exceeds 200KOH+sg/g, the reaction with the acrylic resin will rapidly proceed, gelling will occur, making it difficult to control the reaction, and the acrylic resin will partially form a gel, making it impossible to obtain a uniform solution. The hydroxyl groups other than those involved in the reaction act as crosslinking reactive groups with the curing agent.

Such polyester resins contain carboxylic acid components such as terephthalic acid, isophthalic acid, phthalic anhydride, naphthalene dicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, 1.10 decanedicarboxylic acid, cyclohexanedicarboxylic acid, and trimellitic acid. Polyhydric carboxylic acids such as maleic acid and fumaric acid and their lower alcohol esters, hydroxycarboxylic acids such as paraoxybenzoic acid, and monocarboxylic acids such as benzoic acid can be used.

Examples of alcohol components include ethylene glycol, diethylene glycol, 1,3-propanediol,
1,3-butanediol, 1,4-butanediol, 1
．． 5-bentanediol, 1,6-hexanediol,
1.10-decanediol, 3-methyl-bentanediol, 2.2'-diethyl-1,3-propanediol, 2-ethyl 1,3-hexanediol, neopentyl glycol, trimethylolethane, trimethylolpropane, Glycerin, pentaerythritol, an ethylene oxide adduct of bisphenol A, a -propylene oxide adduct of bisphenol A, an ethylene oxide adduct of hydrogenated bisphenol A, a propylene oxide adduct of hydrogenated bisphenol A, etc. can be used.

Furthermore, it is of course possible to use linseed oil, tung oil, safflower oil, dehydrated castor oil, cottonseed oil, coconut oil, and their fatty acids if necessary.

Such a polyester resin can be obtained by a conventional transesterification method or direct esterification reaction of one or more of the above carboxylic acid components and one or more of the above alcohol components.

The number average molecular weight of the polyester resin measured by GPC method is preferably 500 to 10.000.

The acrylic resin used in the present invention has a hydroxyl value of 5 to
It is necessary to be 200 KOHmg/g, and 20 to
Preferably, it is 150 KOHmg/g. If the hydroxyl value is less than 5 KOHmg/g, the reaction with the polyester resin will proceed sufficiently, but the compatibility will be poor and the resin solution will become cloudy and phase separation will occur. Furthermore, if the hydroxyl value exceeds 200XOB-g/g, the reaction with the polyester resin will proceed rapidly and gelation will occur, making it difficult to control the reaction, and gels will partially form, making it impossible to obtain a uniform solution.

In such an acrylic resin, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, 1,4-butanediol mono (meth)acrylate, etc. can be used as a hydroxyl group-containing monomer.

As comonomers (meth)acrylic acid, itaconic acid,
Maleic acid, fumaric acid and itaconic acid, maleic acid, lower alcohol-modified monoalkyl esters of fumaric acid, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (
meth)acrylate, isobutyl(meth)acrylate, tart-butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, stearyl(meth)acrylate, tridecyl(meth)acrylate, cyclohexyl(meth)acrylate, benzyl(meth)acrylate, Phenyl (meth)acrylate, glycidyl (meth)acrylate, α-methylglycidyl (meth)
Esters of acrylic acid and methacrylic acid such as acrylate, β-methylglycidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate can be used. Other comonomers include styrene, α-
methylstyrene, vinyltoluene, acrylonitrile,
Examples include methacrylonitrile, vinyl acetate, vinyl propionate, acrylamide, methacrylamide, methylol acrylamide, methylol methacrylamide, vinyl chloride, propylene, ethylene, and α-olefins of Ca to Ca11.

Such acrylic resins can be produced by any known polymerization method such as solution polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization. At that time, the polymerization initiators include azobisisobutyronitrile, 4゜4゛-azobis(4-cyanopentaic acid), benzoyl peroxide, t-butylperoxy-2-ethylhexanoate, cumene hydroperoxide, Potassium versalphate, hydrogen peroxide, 2,2°-azobis[2-methyl-N-(2-hydroxyethyl)propioamide], etc. can be used, and if necessary, dodecyl mercaptan is used as a chain transfer agent. , mercaptoethanol, etc. can be used.

The number average molecular weight of the acrylic resin measured by GPC method is preferably 500 to 20,000.

The resin composition (A) of the present invention is a product in which the polyester resin and the acrylic resin have reacted with each other. If the amount is less than 95 parts by weight, only the properties of the polyester resin will be emphasized and it will not be possible to form an excellent coating film that combines the features of both resins, which is the objective of the present invention.On the contrary, if the amount of acrylic resin is more than 95 parts by weight, If the polyester resin is less than 5 parts by weight, only the characteristics of the acrylic resin will be emphasized, making it impossible to achieve the object of the present invention.

The resin composition (A) of the present invention has a polyester resin of 5 to 9
5 parts by weight and 95 to 5 parts by weight of acrylic resin are mixed, 1
It can be produced by reacting at a temperature of 80 to 280°C for 10 minutes to 5 hours, preferably 30 minutes to 3 hours, under conditions that allow the ester groups and hydroxyl groups present in both resins to undergo transesterification. The transesterification reaction does not necessarily need to proceed completely, and may only partially react. After that, a suitable solvent can be added to obtain a resin solution, but in addition, butylated melamine, methylated melamine,
Amino resins such as butylated urea and methylated urea, or polyvalent incyanate compounds such as hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, xylylene diisocyanate, or their water derivatives, trimethylolpropane adducts, isocyanurates, etc. By reacting 0.1 to 5% by weight of the resin solid content, the hydroxyl groups remaining in the acrylic resin and the polyester resin can be mutually bonded and the reaction can proceed.

As the solvent for the resin composition (A) of the present invention, toluene,
Aromatic solvents such as xylene, ester solvents such as ethyl acetate, butyl acetate or cellosolve acetate, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ether solvents such as dioxane and tetrahydrofuran, chlorine solvents such as tetrachloroethane Solvents can be used alone or in combination.

The resin composition (A) in which the polyester resin and acrylic resin of the present invention partially react with each other becomes a uniform resin solution when dissolved in the above-mentioned solvent, and does not undergo phase separation even when left standing and stored. If the mixture undergoes phase separation and becomes a non-uniform solution, it will not be possible to obtain a smooth and glossy coating when used as a paint.

Further, in the present invention, an isocyanate compound is used as the curing agent (B). As an isocyanate compound,
Polyvalent isocyanates such as polyvalent isocyanates, polymers of polyvalent isocyanates, and adducts of polyvalent isocyanates and polyhydric alcohols can be used.

Examples of polyvalent isocyanates include aromatic, aliphatic, or alicyclic isocyanates such as tolylene diisocyanate, metaphenylene diisocyanate, naphthylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, dicyclohexylpropane diisocyanate, and trimethylpentane diisocyanate. Examples include group polyvalent isocyanates.

The isocyanate compounds used in the present invention have unblocked tlM isocyanate groups. Blocked materials require heating during curing and are not preferred.

The isocyanate compounds used in the present invention are all curing agent components that undergo a crosslinking reaction with the hydroxyl groups in the resin composition (A) during curing of the coating material to form a coating film.

The blending ratio of the resin composition (A) and the isocyanate compound in the coating composition is such that the hydroxyl group contained in the resin composition (A) and the isocyanate group in the isocyanate compound are in an equivalent ratio of 1 equivalent of the former to 0 equivalent of the latter. .5 to 2.0 equivalent is desirable; at this equivalent ratio, the isocyanate group is 0.5
If the amount is less than 2.0 equivalent, the crosslinking density of the cured coating film will not be sufficient, so the physical properties of the coating film such as chemical resistance, solvent resistance, water resistance, etc. will be insufficient, and if it exceeds 2.0 equivalents, the cured coating film will be very hard. Become,
It cannot be put to practical use due to its poor flexibility and bendability.

In the urethane coating composition of the present invention, in addition to the resin composition (A) and the curing agent which is an isocyanate compound, even if an acrylic resin and/or polyester resin is additionally added, a uniform resin solution can be obtained. Additional uses of these are also possible. This is considered to be because the resin composition (A) had good compatibility with both resins due to a portion of both resins reacting with each other.

In addition, various materials commonly used in paints include coloring pigments such as titanium oxide, carbon black, red iron, and extender pigments such as clay, calcium carbonate,
Can be used in combination with barium sulfate, talc, alumina, silica, silica powder, etc.

In addition, cellulose derivatives, petroleum resins, phenolic resins, ketone resins, synthetic rubbers, unsaturated polyester resins, natural resins such as rosin, or synthetic resins, leveling agents, anti-sagging agents, antifoaming agents, surfactants, curing accelerators, etc. It is also possible to use various auxiliary agents such as agents.

The coating composition of the present invention can be prepared by a method known per se. For example, the above-mentioned components are mixed and dispersed with an organic solvent using a steel mill, a pebble mill, an attriter, a sand mill, a high-speed stirrer with blades, etc. It can be adjusted by loading it into a machine and mixing and dispersing it uniformly. Examples of organic solvents used in this case include hydrocarbons such as xylene and solvent naphtha, ketones such as methyl isobutyl ketone and cyclohexanone, ethyl acetate, m-ythyl acetate, ethylene glycol monoethyl ether acetate, and ethylene glycol monobutyl ether. Examples include those used in ordinary coating compositions, such as esters and ethers such as acetate and diethylene glycol mobutyl ether acetate.

The amount of the total solvent can be selected within an appropriate range depending on the coating method used, and is approximately 10 to 90% by weight of the total coating composition.

The coating composition of the present invention can be applied to metals, plastics, inorganic materials, inorganic-organic composites, wood products, etc. by conventional coating methods such as spray coating, brush coating, or roll coating. The coating film is usually cured at room temperature, but it is also possible to heat it at 40 to 150°C for 1 minute to 60 minutes.

(Example) Next, the present invention will be specifically explained with reference examples, examples, and comparative examples, and all parts and percentages are based on heavy I unless otherwise specified.

Reference Example 1 (Example of preparation of polyester resin) The raw materials shown in Table 1 were charged into a four-loaf flask equipped with a stirrer, a thermometer, a condenser with a stacked din, and a nitrogen introduction tube.
The reaction was carried out in a nitrogen stream at 220° C. for about 10 hours while distilling off the reaction product to obtain polyester resins A-1 to A-5.

Reference Example 2 (Example of Preparation of Acrylic Resin) 100 parts of pheasant roll was charged into a four-bottle flask equipped with a stirrer, a thermometer, and a condenser, and the temperature was raised to 100°C. The raw materials shown in Table 2 were added dropwise thereto over 4 hours, and the temperature was further maintained for 6 hours to obtain acrylic resins B-1 to B-5 having a solid content of 50%.

Reference Example 3 (Example of Preparation of Resin Composition (A)) The polyester resin and acrylic resin shown in Table 3 were charged into a four-loaf flask equipped with a stirrer, a thermometer, and a condenser with a stacked ring, and heated to raise the temperature. The temperature was raised to 220°C while distilling off the reaction product, and then the reaction was carried out at the same temperature for 1 hour. After cooling, the solvent shown in Table 3 was added to reduce the solid content to 50%.
Resin solutions C-1 to C-3, C-6 and C-9 were obtained.

Further, C-4 was obtained under the same reaction conditions except that the reaction was carried out at 240° C. for 30 minutes. Furthermore, C-5 was obtained in the same manner except that the reaction conditions were 180°C for 3 hours.

Example 1 C-1 of the resin composition (A) shown in Table 3 and the pigment shown in Table 4 were dispersed in a ball mill for 4 hours, and then hardening powder was added with stirring, and further 70 parts of Kijirole and acetic acid were added. ethyl 20
The mixture was diluted with a mixed solvent consisting of 1 part and 10 parts of cellosolve acetate, and the viscosity was adjusted to 125°C for 15 seconds using a Ford Cup 14 to obtain a paint. This was applied to a coated object (Bonderite 1144 zinc phosphate treated steel plate) using air spray and dried at 30°C for 7 days to obtain a test plate. The coating film performance is shown in Table-4.

Examples 2 to 5 Comparative Examples 1 to 4 In the same manner as in Example 1, paints were prepared in the proportions shown in Table 4, and test plates were obtained in the same manner. The coating film performance is shown in Table-4.

l) Orester NP-1000: Aliphatic polyisocyanate (manufactured by Mitsui Toatsu Chemical Co., Ltd.) solid content 75%, NGO content 17%.

2) Rubicron 500RG: Red organic pigment (manufactured by Toyo Soda Co., Ltd.) 3) Drying time After applying Nispray, lightly touch the paint film with your finger. Time until the paint stops sticking to your finger (touch) and strongly press it with your finger. When looking at the time it takes for no marks to be left (curing), those that show a short time are considered to have good drying properties.

4) Appearance of the coating film: The finish of the coating film was visually observed, and a smooth and uniform coating film was evaluated as ◎, a slightly inferior coating film was evaluated as 0, and a coating film with poor uniformity was evaluated as ×.

5) Flexibility: When bent with a curvature of 3■-φ with the coating film facing outward, a sample was rated ◎ if no cracking occurred, and a rated × if a slight crack occurred and a marked O1 crack.

6) Stain resistance: A line was drawn with marker ink, and 24 hours later, the stain was wiped off with methanol. Based on the degree of stain, it was evaluated as total (O1 for no residue, O1 for a little residue, and × for most residue).

7) Weather resistance 100 on sunshine weather meter
The gloss retention rate after testing for 0 hours is displayed.

Claims (1)

[Claims] 5 to 95 parts by weight of polyester resin with a hydroxyl value of 5 to 200 KOHmg/g and a hydroxyl value of 5 to 200 KOHmg/g
Resin composition (A) which reacts with 95 to 5 parts by weight of acrylic resin in g and forms a homogeneous solution when dissolved in a solvent.
and a curing agent (B) which is an isocyanate compound.