JP3041904B2 - Primary color paint for coloring - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a primary color paint for coloring using a pigment dispersing resin which has excellent pigment dispersibility and is well compatible with various resins for coating.

[Prior Art] At present, there are many types of resins used as paint bases according to purposes. For example, when emphasizing appearance, acrylic-based, alkyd-based resins are used, and each of them has a baking type and a room temperature drying type. Sometimes. In addition, resins such as epoxy resins and vinyl resins are also used.

In the case of performing color matching with paint, it is a common method to perform color matching by mixing a plurality of raw material paints based on the same resin. If different resin-based paints are mixed, the compatibility of the resins may not be good, in which case the gloss of the painted surface may be reduced or the physical-chemical performance of the paint itself may be reduced. It will be somewhat impaired.

Therefore, one resin-based paint requires several types of primary color paints, and each other resin-based paint also requires several types of primary color paints. This is not desirable in terms of production efficiency and also causes troubles in production management.

On the other hand, a low-molecular-weight resin compatible with a relatively wide range of resins, for example, a low-molecular-weight resin such as urea-based, triazine-based, polyglycol-based, and acrylic-based resins, and a primary color paint in which a pigment is dispersed therein. It has been conceived to avoid the above-mentioned problems in production efficiency and the like by preparing.

However, such a low molecular weight resin is inevitably inferior in that the properties of the coating film and the durability of the coating film are generally deteriorated when the resin is mixed with various resins for coating.

[Problems to be solved by the invention]

As described above, in the related art, pigment dispersing resins that are well compatible with various resins for paints and can exhibit good coating film properties have hardly been found, and their appearance is strongly desired. Was.

In view of the above-mentioned conventional circumstances, the present invention has excellent dispersibility of pigments, and is well compatible with resins for various coatings such as alkyd, acrylic, vinyl, and epoxy, and is mixed with these resins. It is an object of the present invention to provide a coloring primary color paint using a pigment dispersing resin capable of imparting good coating properties without impairing the original performance of each resin when the resin is used.

[Means for solving the problem]

The present inventors have conducted intensive studies to achieve the above object, and as a result, a urethane-modified polyester resin obtained by reacting a specific polyester prepolymer with a polyfunctional isocyanate compound has a good compatibility with a wide range of resins. The present invention has been found to be soluble and exhibit good pigment dispersibility, and the present invention has been completed.

That is, the present invention relates to a polyester prepolymer having a number average molecular weight of 350 to 1,500 and a hydroxyl value of 100 to 300, wherein the isocyanate group has a ratio of 0.2 to 0.7 equivalent to 1 equivalent of the hydroxyl group of the prepolymer. Coloring obtained by dispersing a pigment in an organic solvent solution of a pigment dispersing resin comprising a urethane-modified polyester resin having a hydroxyl value of 40 to 240 and a number average molecular weight of 700 to 2,000 obtained by reacting a polyfunctional isocyanate compound. It relates to the primary color paint.

[Structure and operation of the invention]

The polyester prepolymer used as an intermediate raw material in the present invention can be obtained by subjecting a polyhydric alcohol, a polybasic acid and, if necessary, other organic acids to application raw materials to condensation polymerization by a well-known method. Can be.

Examples of the polyhydric alcohol include dihydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, polypropylene glycol, neopentyl glycol and hexylene glycol, glycerin, and trimethylo. -One or more of ethane, trimethylolpropane and the like can be used in combination.

As polybasic acids, hexahydrophthalic anhydride, phthalic anhydride, isophthalic acid, tetrahydrophthalic anhydride,
One or a mixture of two or more of various polybasic acids generally used for the production of polyesters such as trimellitic anhydride, adipic acid, sebacic acid and maleic anhydride can be used. Among them, it is particularly preferable to use hexahydrophthalic anhydride from the viewpoint of physical properties, weather resistance, compatibility and the like.

As other organic acids used as necessary, fatty acids having 8 to 18 carbon atoms, dimer acid, benzoic acid and the like can be used.

The polyester prepolymer of the present invention obtained from such a starting material has a number average molecular weight of 350 to 1,500, preferably 500 to 1,000, and a hydroxyl value of 100 to 300, preferably 110 to 200. . Further, the glass transition temperature is preferably in the range of -20 to 50C.

If the number-average molecular weight is less than 350, the resulting urethane-modified polyester resin has poor physical properties and weather resistance, etc.
If it exceeds 0, the compatibility between the above resin and other resins deteriorates. If the hydroxyl value is less than 100 or exceeds 300, the resulting urethane-modified polyester resin has poor durability and compatibility with other resins. If the glass transition temperature is too low, a sticky feeling remains in the coating film,
On the other hand, if it is too high, physical properties such as impact resistance and bending resistance of the coating film are deteriorated, and neither is preferable.

In the present invention, a urethane-modified polyester resin is produced by using the above-mentioned specific polyester prepolymer as an intermediate material and reacting it with a polyfunctional isocyanate compound.

As the polyfunctional isocyanate compound used here,
Examples thereof include hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate and dimers and trimers thereof. These isocyanate compounds and water, ethylene glycol, Reaction products with polyhydric alcohols such as propylene glycol can also be used. These compounds all have two or three isocyanate groups per molecule.

The amount of the polyfunctional isocyanate compound used is such that the isocyanate group is 0.2 equivalent to 1 equivalent of the hydroxyl group of the prepolymer.
~ 0.7 equivalents, preferably as a ratio to become 0.3 to 0.6 equivalents, the hydroxyl value of the resulting urethane-modified polyester resin is 40 to 240, preferably 50 to 150, the number average molecular weight is
It is good to be 700 to 2,000, preferably 1,000 to 1,9000.

Since such a urethane-modified polyester resin has a skeleton composed of a polyester resin, it is inherently low in viscosity and excellent in pigment dispersibility as compared with other resins, and has good compatibility with other resins. A urethane bond is introduced into the molecule, and the hydroxyl value is set to an optimum solubility parameter value to be 40 to 240, and the molecular weight is adjusted to the film-forming function and compatibility with other resins. By setting the optimum range in consideration of the above, the above-mentioned original characteristics are further promoted, and excellent performance desired for pigment dispersion is exhibited.

If the amount of the polyfunctional isocyanate compound falls outside the above range and the hydroxyl value and the number average molecular weight of the resulting urethane-modified polyester resin deviate from the above ranges, the dispersibility of the pigment, the physical properties of the coating film and the weather resistance If the glossiness of the coated surface is lowered in addition to the deterioration of the properties and the compatibility with the various resins for coating and the deterioration of the properties of the coating film, various problems are caused.

In the present invention, when the above-mentioned urethane-modified polyester resin is used as a resin for dispersing a pigment, the resin is generally used as a base, and a color pigment, an organic solvent, and if necessary, a fluidity adjusting agent, a surface tension adjusting agent, and a pigment dispersing agent. Ingredients and the like can be mixed to prepare each inter (primary color paint for coloring in which a single pigment is dispersed).

Examples of the coloring pigment include titanium oxide, red iron oxide, chrome yellow, carbon black, quinacridone-based, perylene-based, azo-based pigment, phthalocyanine, and the like. You can use all of the pigments that are available. In the case of the intercoat, the pigment concentration is designed to be several times higher than that of a normal paint in order to reduce the amount of mixing in each resin-based paint.

As the organic solvent, for example, a hydrocarbon solvent, an ester solvent, a ketone solvent, an alcohol solvent, a cellosolve solvent, and the like are used. However, the solvent is not limited thereto, and various solvents generally used for paints can be widely used.

〔The invention's effect〕

The pigment dispersing resin of the present invention shows good dispersibility for various organic pigments and inorganic pigments, and also shows good compatibility with many resins used for coatings. The dried alkyd paint is a room temperature drying type alkyd paint.
It can be used for coloring paints such as baked alkyd paints, room temperature dry acrylic paints, baked acrylic paints, vinyl chloride paints, epoxy paints and nitrocellulose paints. As a result, the type of the interface can be greatly reduced, and the productivity of the paint can be remarkably improved.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The parts in the examples are parts by weight. Further, the polyester prepolymer solutions E1 to E8 used in the following Examples and Comparative Examples, a urethane-modified polyester resin solution UE
1 to UE5 and the test acrylic varnish AC9 were each prepared by the following method.

<Preparation of Polyester Prepolymer> In a flask equipped with a stirrer, a rectification tower, a water separator cooling tube, a thermometer and a nitrogen gas inlet, based on the formulation shown in Table 1, polybasic acid and polyhydric alcohol were used. Then, the mixture was heated and stirred in a nitrogen gas atmosphere, and the temperature was raised from 160 ° C. to 230 ° C. over 4 hours while distilling off the condensed water generated outside the system. Then, 1.5% by weight based on the contents of the flask
Of xylene was gradually added, and the condensation reaction was continued while maintaining the temperature at 230 ° C. The reaction is terminated when the acid value becomes 10 or less,
After dilution with the remaining xylene, eight types of polyester prepolymer solutions E1 to E8 were obtained. The measurement results of the number average molecular weight, hydroxyl value, acid value and the like of each prepolymer were as shown in Table 1 below.

<Preparation of urethane-modified polyester resin solution> Polyester prepolymer solutions E1 to E4 prepared above
After cooling E7 and E7 to 80 ° C., respectively, a polyfunctional isocyanate compound shown in Table 2 was added, and stirring was continued at 80 ° C. for 3 hours, and unreacted isocyanate groups were traced by infrared absorption spectrum analysis. did. The reaction was terminated when the isocyanate group disappeared, and five types of urethane-modified polyester resin solutions UE1 to UE5 were obtained. The nonvolatile content, viscosity (gardner, 25 ° C.), resin acid value and the like of each solution were as shown in Table 2 below.

<Preparation of acrylic varnish for test> Charge 40 parts of xylene and 10 parts of butyl alcohol
In a reaction vessel heated to 135 ° C, methyl methacrylate 2
A mixture of 8 parts, 13 parts of butyl acrylate, 5 parts of β-hydroxyethyl methacrylate, 1 part of acrylic acid and 1 part of cumene hydroperoxide was added dropwise over 3 hours, and stirring was continued at the same temperature for 2 hours. Thus, a test acrylic varnish AC9 was obtained.

Examples 1-4 and Comparative Examples 1-4 Urethane-modified polyester resin solutions UE1 shown in Table 2
To UE4 is the resin solution for pigment dispersion of the present invention (Examples 1 to 4)
And a urethane-modified polyester resin solution UE5 shown in Table 2 and a polyester prepolymer solution E shown in Table 1
5, E6, E8 and a pigment dispersion resin solution for comparison (Comparative Examples 1 to 5)
4).

Using each of these pigment dispersion resin solutions, the following compatibility test (Test I), paint preparation test (Test II), and toning test (Test III) were performed.

<Test I; Compatibility Test> Four types of general paint varnishes shown in Table 3 below and each of the pigment dispersing resin solutions were mixed so that the resin solid component weight ratio was 8/2. This mixture was flow-coated on a glass plate, and then the dried coating film was checked for scumming. A transparent sample was represented by ○ (pass), and a cloudy one was represented by × (fail). The results were as shown in Table 3.

<Test II; paint preparation test> § Preparation of inter-white Based on each pigment dispersion resin solution, 60 parts of titanium oxide RCR3 (ICI) and 15 parts of xylene were used for 20 parts of each.
Part, methoxypropyl acetate (hereinafter referred to as MPA)
Was mixed and dispersed by a sand mill until the particle size became 10 μm or less, thereby preparing eight kinds of inter-whites W1 to W8.

§Preparation of white paint The above-mentioned white paints W1 to W8 were mixed in the following composition to prepare eight kinds of white paints WP1 to WP8, and then mixed thinner of xylene and MPA at a weight ratio of 7/3. Was used to dilute to a sprayable viscosity.

§Formation of coating film The white paints WP1 to WP8 diluted as described above were sprayed on a 0.8 mm x 70 mm x 150 mm steel plate (hereinafter referred to as a treated steel plate) treated with zinc phosphate so that the dry film thickness became 30 µm. After painting and baking at 140 ° C. for 20 minutes, the state of the coated surface, physical properties of the coating film and durability were evaluated. The results were as shown in Table 4 below.

<Test III; Toning test> §Preparation of inter-black Based on each pigment dispersion resin solution, carbon black (COLOR BLACK FW200: DEXA) for each 60 parts
Was mixed with 25 parts of xylene and 10 parts of MAP, and dispersed by a sand mill until the particle size became 10 μm or less, thereby preparing eight kinds of inter-blacks B1 to B8.

§Preparation of Inter Blue Based on each of the pigment dispersion resin solutions, 30 parts of phthalocyanine bullion (Rionol-PR-PRX; manufactured by Toyo Ink Mfg. Co., Ltd.) and 15 parts of xylene were added to 50 parts of each. And MAP were mixed and dispersed by a sand mill until the particle size became 10 μm or less, thereby preparing eight kinds of inter-blues F1 to F8.

§Preparation of toning paints Using the eight kinds of white paints WP1 to WP8 prepared in Test II, and the above-mentioned inter-black B1 to B8 and inter-blue F1 to F8, the following formulation and By mixing in the combinations shown in the table, eight kinds of toning paints P1 to P8 were prepared.

§ Physical properties of coating film and standing stability The above-mentioned toning paints P1 to P8 were subjected to the following rubbing test, 60-degree specular gloss test and rattaning test. The results were as shown in Table 5 below.

(Rubbing test)

The above toning paints P1 to P8 were mixed with xylene and MPA at a weight ratio of 7/3.
The mixture was diluted to a viscosity that could be sprayed with a mixed thinner, and the diluted paint was applied to a 50 mm × 150 mm tin plate by flowing, and allowed to stand in a room at room temperature for 3 minutes.
The difference in color from the unrubbed part was compared. A sample having almost no color difference was evaluated as ○, and a sample having large color difference was evaluated as ×.

[60 ° specular gloss test] The tin plate used for the rubbing test was further heated to 140 ° C and 20 ° C.
After baking and drying, the glossiness of the coating film was measured. Pass 80 or more.

[Standing test]

Each diluted paint prepared by the rubbing test was put into a test tube, and after 3 days, a color-separated state was observed. The ones with little color separation and color floating were rated as ○, and those with color separation and strong color floating were rated as x.

As is clear from the results of Tables 3 to 5, the pigment dispersing resin of the present invention has good compatibility with various resins and exhibits excellent pigment dispersing properties. Recognize.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-178172 (JP, A) JP-A-61-171719 (JP, A) JP-A-54-135823 (JP, A) JP-A-4- 264128 (JP, A) Patent 2861402 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 17/00 C09D 175/00-175/16 C08G 18/00-18/87 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] (1) a number average molecular weight of 350 to 1,500 and a hydroxyl value of 10
In a polyester prepolymer of 0 to 300, isocyanate groups are contained in an amount of 0.2 to 0.7 with respect to 1 equivalent of a hydroxyl group of the prepolymer.
The hydroxyl value obtained by reacting a polyfunctional isocyanate compound in an equivalent ratio is 40 to 240, and the number average molecular weight is 700.
A primary color paint for coloring obtained by dispersing a pigment in an organic solvent solution of a pigment dispersing resin composed of up to 2,000 urethane-modified polyester resins.