JPH04220424A - Resin used for dispersing pigment - Google Patents

Abstract

PURPOSE:To provide the title resin which is highly compatible with many kinds of resins for coating materials and gives a coating film having excellent properties. CONSTITUTION:A urethane-modified polyester resin which is prepd. by reacting an amine-modified polyester prepolymer obtd. using an aminoalcohol as a constituent of an alcohol component with a polyisocyanate compd. and has a hydroxyl value of 40-200 and a number-average mol. wt. of 700-2,000 is used as the pigment dispersing resin.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin for dispersing pigments which has excellent pigment dispersibility and is well compatible with various resins for paints.

0002

BACKGROUND OF THE INVENTION At present, there are many types of resins used as bases for paints depending on the purpose. For example, if appearance is important, acrylic and alkyd resins are used, and each of these has a baking type and room temperature drying type, and depending on the purpose, baking type acrylic paint uses resins with different properties. Sometimes. In addition, epoxy resins, vinyl resins, and other resins are also used.

[0003] When performing color matching using paints, the usual method is to mix a plurality of primary color paints based on the same resin. If paints made of different resins are mixed together, the compatibility of the resins may not be good, and in that case, the gloss of the painted surface may decrease, or
In addition, the original physical and chemical properties of the paint will be impaired to some extent.

[0004] Therefore, one resin-based paint requires several types of primary-color paints, and similarly, each resin-based paint requires several types of primary-color paints. The number of types is enormous, which is not desirable in terms of production efficiency, and also causes trouble in production management.

On the other hand, using low-molecular resins that are compatible with a relatively wide range of resins, such as urea-based, triazine-based, polyglycol-based, and acrylic-based resins,
It is considered that the above-mentioned problems in terms of production efficiency can be avoided by preparing primary color paints in which pigments are dispersed. However, when such low-molecular resins are mixed with various resins for paints,
However, the physical properties of the coating film and the durability of the coating film were generally poor.

[Problems to be Solved by the Invention] As described above, in the past, resins for pigment dispersion that are compatible with various resins for paints and can exhibit good coating properties are It had hardly been discovered, and its appearance was strongly desired.

In view of the above-mentioned conventional circumstances, the present invention provides pigments that have excellent dispersibility and are well compatible with resins for various paints such as alkyd, acrylic, vinyl, and epoxy paints. The object of the present invention is to provide a resin for pigment dispersion which, when mixed with a resin, can impart good coating film properties without impairing the inherent performance of each resin.

[Means for Solving the Problems] As a result of intensive studies to achieve the above object, the present inventors have developed a specific polyester prepolymer using amino alcohol as a type of alcohol component as an intermediate raw material. The present invention was completed based on the discovery that a urethane-modified polyester resin obtained by reacting this with a polyfunctional isocyanate compound is well compatible with a wide range of resins and exhibits good pigment dispersibility.

That is, the present invention involves a condensation reaction using, in addition to a polybasic acid and a polyhydric alcohol, an amino alcohol in a proportion of 0.5 to 7.0% by weight in the raw material of the polyester prepolymer as an essential component. The obtained amine-modified polyester prepolymer having a number average molecular weight of 350 to 1500 and a hydroxyl value of 100 to 300 has an isocyanate group of 0.1 to 0 per equivalent of hydroxyl group in this prepolymer.
．． A resin for pigment dispersion characterized by 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 in a proportion of 7 equivalents. It is.

0010

Structure and operation of the invention The amine-modified polyester prepolymer used as an intermediate raw material in the present invention contains an amino alcohol as an essential component in addition to a polybasic acid and a polyhydric alcohol, and further contains other organic acids as necessary. It can be obtained by subjecting these to a condensation reaction using a well-known method as a starting material.

Examples of polybasic acids include various polybasic acids commonly used for producing polyesters, such as hexahydrophthalic anhydride, phthalic anhydride, isophthalic acid, tetrahydrophthalic anhydride, trimellitic anhydride, adipic acid, and sebacic acid. Examples include acids, and one or more of these may be used. From the viewpoint of physical properties, weather resistance, compatibility, etc., hexahydrophthalic anhydride is particularly preferred.

[0012] Polyhydric alcohols include ethylene glycol, propylene glycol, diethylene glycol,
polypropylene glycol, neopentyl glycol,
In addition to dihydric alcohols such as hexylene glycol, trivalent or higher polyhydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol may be mentioned, and one or more of these may be used. used.

The amino alcohol has the following general formula; N(R1)(R2)(R3) [wherein R1, R2, R
3 is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, 1 carbon number
A group selected from a hydroxyalkyl group having ~18 carbon atoms or a dihydroxyalkyl group having 2 to 18 carbon atoms,
The groups may be the same or different, but at least one is a hydroxyalkyl group having 1 to 18 carbon atoms. Monovalent to trivalent amino alcohols are preferably used.

Specific examples of such amino alcohols include monoalcohol amines such as aminopropanol, N-dimethylaminopropanol, and N-dodecylaminoethanol, 2-(N-hydroxymethylamino)ethanol, N-isobutyldiethanolamine, Dialcoholamines such as N-methyldibutanolamine, triethanolamine, tributanolamine, and the like may be mentioned, and one or more of these may be used.

The amount of amino alcohol used is 0 in the total raw materials for obtaining the amine-modified polyester prepolymer.
．． It is necessary to set it within the range of 5 to 7.0 weight%, and it is particularly preferable to set it within the range of 1.0 to 5.0 weight%. If it is less than 0.5% by weight, the dispersibility of the pigment will be poor, and if it exceeds 7.0% by weight, the durability of the coating film will be poor and it may also cause discoloration of the coating film.

Other organic acids that may be used as necessary include fatty acids having 8 to 18 carbon atoms, dimer acid, benzoic acid, and the like. The amount of these organic acids used is preferably suppressed to 10% by weight or less based on the total raw materials for obtaining the amine-modified polyester prepolymer.

The amine-modified polyester prepolymer, which is the intermediate raw material of the present invention, obtained by condensation reaction of such starting materials has a number average molecular weight of 350 to 1500.
It is necessary that the hydroxyl value is 100 to 300, particularly preferably a number average molecular weight of 500 to 1000 and a hydroxyl value of 110 to 250. Further, the acid value is preferably 15 or less. Number average molecular weight is 350
If it is less than 1,500, the physical properties and weather resistance of the final target urethane-modified polyester resin will deteriorate, and if it exceeds 1,500, the compatibility between the resin and various resins for other paints will be poor. Furthermore, if the hydroxyl value is less than 100 or more than 300, the durability of the urethane-modified polyester resin and the compatibility with various resins for other paints will deteriorate.

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

Examples of the polyfunctional isocyanate compounds used here include hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, dimers and trimers thereof, and combinations of these isocyanate compounds with water, ethylene glycol, propylene glycol, etc. Examples include reactants with polyhydric alcohols,
One or more of these may be used. Each of these compounds has two or three isocyanate groups per molecule.

The amount of such a polyfunctional isocyanate compound to be used should be such that the amount of isocyanate group is 0.1 to 0.7 equivalent per equivalent of hydroxyl group of the amine-modified polyester prepolymer, and is particularly preferable. is 0.2~
It is preferable to set the ratio to be 0.6 equivalent. If the amount is less than 0.1 equivalent, the dispersibility of the pigment, physical properties of the coating film, weather resistance, etc. will deteriorate, and if it exceeds 0.7 equivalent, the molecular weight of the urethane-modified polyester resin, which is the reactant, will become too high, and other The compatibility with various resins for paints deteriorates.

The urethane-modified polyester resin of the present invention thus obtained has a hydroxyl value of 40 to 240.
It is important that the number average molecular weight is set to 700 to 2000, and particularly preferably the hydroxyl value is set to 50 to 150.
The number average molecular weight is preferably set to 1,000 to 1,900. Further, the acid value is preferably 15 or less. When the hydroxyl value is less than 40 or exceeds 240, the durability of the coating film becomes poor and the compatibility with various resins for paints becomes poor. If the number average molecular weight is less than 700, the physical properties and weather resistance of the coating film will be poor, and if it exceeds 2000, the compatibility with various resins for paints will be poor.

[0022] Since such a urethane-modified polyester resin has a skeleton made of polyester resin, it has an inherently low viscosity and excellent pigment dispersibility compared to other resins, and also has good compatibility with other resins. Furthermore, a urethane bond is introduced into this molecule along with an amino group, and the hydroxyl value is 4.
Set the optimum solubility parameter value between 0 and 240,
In addition, by setting its molecular weight to an optimal range that takes into account film-forming function and compatibility with other resins, the above-mentioned original properties are further enhanced, and the excellent performance desired for pigment dispersion is achieved. demonstrate.

In the present invention, when the above-mentioned urethane-modified polyester resin is used as a resin for pigment dispersion, this resin is generally used as a base, and a colored pigment, an organic solvent, and if necessary, a fluidity regulator, a surface tension regulator, and a pigment are added. Each inter (primary color paint for coloring in which a single pigment is dispersed) can be prepared by blending a dispersant and the like.

Coloring pigments include inorganic pigments such as titanium oxide, Bengara, chrome yellow, phthalocyanine blue,
Organic pigments such as quinacridone, perylene, and azo pigments,
Examples include, but are not limited to, carbon black, and all color pigments commonly used for paints can be used.

Examples of organic solvents include, but are not limited to, hydrocarbon-based, ester-based, ketone-based, alcohol-based, and glycol-based solvents. Can be used widely.

[0026]

Effects of the Invention The pigment dispersing resin of the present invention exhibits good dispersibility for various organic pigments and inorganic pigments, and also exhibits good compatibility with many resins used for paints.
Inter, which has pigments dispersed in this resin, can be used for paints such as room temperature drying alkyd paints, baking type alkyd paints, room temperature drying type acrylic paints, baking type acrylic paints, vinyl chloride paints, epoxy paints, and nitrocellulose paints. It can be used for coloring, and as a result, the number of interspersions can be greatly reduced, and the productivity of paints can be significantly improved.

[0027]

[Examples] Next, the content of the present invention will be explained in more detail with reference to Examples and Comparative Examples. Note that parts in the examples are parts by weight. In addition, amine-modified or unmodified polyester prepolymer solutions E1 to E8, urethane-modified polyester resin solutions UE used in the following Examples and Comparative Examples
1 to UE7 and test acrylic varnish AC9 were each prepared in the following manner.

<Preparation of polyester prepolymer solution>
Into a flask equipped with a stirrer, a rectification column, a water separator cooling tube, a thermometer, and a nitrogen gas inlet, add polybasic acids and polyhydric alcohols, or their combinations, based on the formulations shown in Tables 1 and 2 below. The mixture was heated and stirred in a nitrogen gas atmosphere, and the temperature was raised from 160°C to 230°C at a constant temperature increase rate over 4 hours while distilling the condensed water produced out of the system.

Thereafter, 1.5 parts of xylene was gradually added, and the condensation reaction was continued while maintaining the temperature at 230°C. Acid value 10
When the following is reached, the reaction is terminated, diluted with the remaining xylene, and 8 types of polyester prepolymer solutions E1 to E are prepared.
I got 8. Among these, sample number E6 is an amine-unmodified polyester prepolymer solution, and all the others are amine-modified polyester prepolymer solutions.

The number average molecular weight, hydroxyl value and acid value of each polyester prepolymer obtained are measured, and the results are calculated as the proportion (wt%) of the amino alcohol used in the production of each polyester prepolymer in the total raw material. and the solid content concentration of each polyester prepolymer solution are also listed in Tables 1 and 2. The viscosity (Gardner; 25° C.) of the polyester prepolymer solution E8 was Z3.

[0031]

[Table 1]

[0032]

[Table 2]

<Preparation of urethane-modified polyester resin solution> Polyester prepolymer solution E1 prepared above
~E7, respectively, after cooling to 80°C, the following Table 3
, the polyfunctional isocyanate compounds shown in Table 4 were added, and 80
While stirring was continued for 3 hours at °C, unreacted isocyanate groups were monitored by infrared absorption spectrum analysis. The reaction was terminated when the isocyanate group disappeared, and seven types of urethane-modified polyester resin solutions UE1 to UE7 were obtained.

The hydroxyl value, number average molecular weight and acid value of each of the obtained urethane-modified polyester resins were measured, and the results are tabulated along with the solid content concentration and viscosity (Gardner; 25°C) of each urethane-modified polyester resin solution. 3. Also listed in Table 4.

[0035]

[Table 3]

[0036]

[Table 4]

<Preparation of acrylic varnish for testing> Add 40 parts of xylene and 10 parts of butyl alcohol,
28 parts of methyl methacrylate, 13 parts of butyl acrylate, 5 parts of β-hydroxyethyl methacrylate, 1 part of acrylic acid, and 1 part of cumene hydroperoxide are placed in a reaction vessel heated to ℃ and refluxing these solvents. The mixed solution was added dropwise over 3 hours, and stirring was continued for 2 hours at the same temperature to obtain test acrylic varnish AC9.

Examples 1 to 3 and Comparative Examples 1 to 5 The urethane modified polyester resin solutions UE1 to UE3 shown in Table 3 were used as the resin solutions for pigment dispersion of the present invention (Examples 1 to 3), and the urethane modified polyester resin solutions UE1 to UE3 shown in Table 4 were used as the resin solutions for pigment dispersion of the present invention (Examples 1 to 3). Modified polyester resin solution UE4
~UE7 and the amine-modified polyester prepolymer solution E8 shown in Table 2 were used as comparative pigment dispersion resin solutions (Comparative Examples 1 to 5).

Using each of these pigment dispersion resin solutions,
The following compatibility test (Test I), paint formulation test (Test II)
) and a color toning test (Test III) were conducted.

<Test I; Compatibility test> Four types of general paint varnish shown in Table 5 below and each resin solution for pigment dispersion were mixed so that the weight ratio of the resin solid content was 8/2. After applying this mixture onto a glass plate, the degree of turbidity of the dried coating film was examined. Transparent samples were marked with ○ (pass), and cloudy samples were marked with × (fail). The results are also listed in Table 5.

[0041]

[Table 5]

In Table 5, "room temperature drying alkyd varnish" is 60% oil length soybean oil fatty acid modified phthalic acid varnish (solid content 55% by weight), "melamine/alkyd varnish" is n
-Mixture varnish (solid content 50% by weight) of butanol-modified melamine resin varnish and 40% oil length soybean oil fatty acid-modified phthalic acid varnish (solid content 50% by weight), "melamine/acrylic varnish" is n-butanol-modified melamine A mixed varnish (solid content 50% by weight) of resin varnish and test acrylic varnish AC9 at a solid content weight ratio of 2/8, "vinyl chloride varnish" is a vinyl chloride-vinyl acetate copolymer varnish (Vinylite VAGH manufactured by Union Carbide) ; solid content 20% by weight).

<Test II; Paint formulation test> Preparation of interwhite Based on each pigment dispersion resin solution, for each 20 parts, 60 parts of titanium oxide RCR3 (BTP), 15 parts of xylene, and methoxy Propyl acetate (hereinafter referred to as MP
5 parts of A) were mixed and sand milled to a particle size of 10.
8 types of inter white W1 are dispersed until it becomes less than μm.
~W8 was prepared.

§ Preparation of white paint 30 parts each of the above Interwhites W1 to W8, 58 parts of test acrylic varnish AC9 (solid content 50% by weight), and melamine varnish [Melan # manufactured by Hitachi Chemical Co., Ltd.] 28; Solid content 60% by weight] 12 parts and 8 types of white paint W
P1 to WP8 were prepared. These paints are mixed with xylene and M
It was diluted to a sprayable viscosity using a mixed thinner with PA in a 7/3 weight ratio.

§ Formation of coating film The white paints WP1 to WP8 diluted as above were applied to a 0.8 mm x 70 mm x 150 mm steel plate (
The coated steel sheet (hereinafter referred to as treated steel sheet) was spray coated to a dry film thickness of 30 μm, baked at 140° C. for 20 minutes, and then the coated surface condition, coated film physical properties, and durability were evaluated. The results are shown in Table 6 below.

[0046]

[Table 6]

[0047] In Table 6, "60 degree specular gloss" is J
According to IS-K-5400 (1979) 6.7, 8
A score of 0 or more was considered a pass. "Pencil traction test" is JIS-
According to K-5400 (1979) 6.14, H
Those harder than B were accepted. "Checker board test" is JIS
-K-5400 (1979) 6.15,
A score of 10 points was considered a pass, and a score of 8 or less was considered a fail. In addition, "impact resistance" is JIS-K-5400 (1979) 6.1
3.3 According to method B, a length of 40 cm or more was considered to be a pass. "Accelerated weathering test" is JIS-K-5400 (1979
) According to 6.17, the retention rate (%) of the 60 degree specular gloss after the 800-hour test was determined as [(gloss after test)/(initial gloss)] x 100, and 70% or more was determined. Passed.

<Test III; Toning test> §9 Preparation of inter black Based on the resin solution for dispersing each pigment, add carbon black (COLOR BLACK) to 60 parts of each resin solution.
FW200: Dexa) 5 parts, xylene 25 parts, M
Eight types of interblacks B1 to B8 were prepared by mixing 10 parts of PA and dispersing the mixture in a sand mill until the particle size became 10 μm or less.

Preparation of Inter Blue Based on each pigment dispersion resin solution, 50 parts of each are mixed with phthalocyanine blue [Lionol Blue PRX;
Toyo Ink Mfg. Co., Ltd.], 30 parts of xylene, 15 parts of MPA, and 5 parts of MPA were mixed and dispersed in a sand mill until the particle size was 10 μm or less to produce 8 types of Inter Blue F1 to F8.
was prepared.

§90 parts each of the eight types of white paints WP1 to WP8 prepared in the toning paint preparation test II, and 5 parts each of the above interblacks B1 to B8,
5 parts each of Inter Blue F1 to F8 above, and Table 7 below.
Eight types of toning paints P1 to P are mixed in the combinations shown below.
8 was prepared.

[0051]

[Table 7]

§Coating film properties and storage stability The above-mentioned toning paints P1 to P8 were subjected to the following rubbing test, 60 degree specular gloss test and standing test. The results are also listed in Table 7.

[Rubbing test] The above color toning paints P1~
P8 was diluted to a sprayable viscosity with a thinner mixture of xylene and MPA in a weight ratio of 7/3, and this diluted paint was poured onto a 50 mm x 150 mm tin plate, left to stand indoors for 3 minutes at room temperature, and then , I rubbed the painted surface with my finger and compared the difference in color with the part that was not rubbed. A sample with almost no color difference was graded ○, and a sample with a large color difference was graded x.

[60 degree specular gloss test] The tin plate used in the rubbing test was further baked and dried at 140° C. for 20 minutes, and the gloss of the coating film was measured. A score of 80 or higher was considered a pass.

[Standing Test] Each diluted paint prepared in the rubbing test was placed in a test tube, and the state of color separation was observed after 3 days. Those with almost no color separation or color floating were rated as ○, and those with severe color separation or color floating were rated as ×.

As is clear from the results in Tables 5 to 7 above, the pigment dispersing resin of the present invention has good compatibility with various resins for paints and exhibits excellent pigment dispersibility. I understand that there is something.

Claims (1)

[Claims] Claim 1: A number average obtained by a condensation reaction using, in addition to a polybasic acid and a polyhydric alcohol, an amino alcohol in a proportion of 0.5 to 7.0% by weight in the raw material of the polyester prepolymer as an essential component. Molecular weight is 350-150
0. Obtained by reacting an amine-modified polyester prepolymer with a hydroxyl value of 100 to 300 with a polyfunctional isocyanate compound in a proportion of 0.1 to 0.7 equivalents of isocyanate groups per 1 equivalent of hydroxyl groups in this prepolymer. with a hydroxyl value of 40 to 240 and a number average molecular weight of 700 to 2.
A resin for pigment dispersion characterized by comprising a urethane-modified polyester resin of No. 000.