JPS63132974A - Pigment-dispersed paste - Google Patents

Abstract

PURPOSE:To provide the titled paste outstanding in pigment dispersibility, storage stability and compatibility with various resins, etc., improved in weatherability, gloss, etc., comprising a dipolar ionic group-contg. aminoplast resin, pigment and solvent in specified proportions. CONSTITUTION:The objective paste with good dispersibility even for sparingly dispersible pigment having quinacridone skeleton, capable of incorporation in various coatings, comprising (A) an aminoplast resin with an average weight- average molecular weight 900-40,000, having in one molecular dipolar ionic group of formula -N<+>-R-Y<-> (R is 1-6C alkylene or phenylene; Y<-> is -COO<-> or -SO2<->) with a dipolar ionic group value 2-40 (expressed by mg number of KOH necessary for neutralization of the dipolar ionic group contained in 1g of the resin), (B) a pigment and (C) a solvent in the weight ratio A/B=5/95-95/5 (on a solid basis).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a pigment dispersion paste, and more particularly to a general-purpose pigment dispersion paste consisting of an aminoplast resin face having an amphoteric group and a pigment.

PRIOR ART When making a colored paint, it is usual to first make a pigment dispersion paste by dispersing a coloring agent such as a pigment into a part of the paint's base resin vehicle, and then to mix the dispersed paste uniformly into the paint. It is being done. A dispersion paste obtained by dispersing pigments etc. in a resin vehicle different from the base resin of the paint is sometimes used, but the resin for the pigment paste and the base resin of the paint must be compatible; Since an extremely wide variety of resins are used, it is extremely difficult to obtain a pigment dispersion paste that is versatile. Furthermore, as a resin for pigment dispersion paste, it must have good pigment dispersibility and must not have a negative effect on coating film performance. Since a variety of resins are used, it is extremely difficult to select a resin that exhibits good dispersibility for any of them.

The applicant previously developed a resin vehicle that exhibits good dispersibility for various pigments, especially difficult-to-disperse quinacridone pigments, by supporting an acidic resin and an amino resin with reactive functional groups, respectively, and reacting them. It was discovered that an amphoteric resin having a predetermined acidity and basicity is extremely useful, and a patent application was filed (Japanese Patent Laid-Open No. 58-21468).

However, in this case, the acidic resin is the same type as the paint base resin, so it is not possible to incorporate a dispersion paste using the amphoteric resin into any paint, and the dispersibility may be affected by the pigment. In order to obtain good results, it was necessary to control the melamine resin selected, the molecular weight of the resulting amphoteric resin, the glass transition temperature, etc. Even more.

It was pointed out that it was necessary to consider the coating film performance of the pigment dispersion resin itself.

Problems that the invention aims to solve: This resin is easily obtained, has good dispersibility even for difficult-to-disperse pigments with a quinacridone skeleton, such as Shinkasha Red, and can be incorporated into various paints. Moreover, there is a demand for pigment dispersion resins and pigment dispersion pastes with excellent coating film performance, and it is an object of the present invention to meet such problems.

Means for Solving the Problems According to the present invention, the above-mentioned object of the invention is achieved when the weight average molecular weight is 900 to 40. OOQ, an aminoplast resin having an amphoteric group in the molecule represented by the formula (wherein R is 01 to C6 alkylene or phenylene which may have a substituent;
This is achieved by a pigment dispersion paste consisting of a pigment and a solvent, characterized in that the solid content weight ratio of the aminoplast resin to the pigment is 5/95 to 9515.

The aminoplast resin used in the present invention has a weight average molecular weight of 900 to 40,000 and has a formula in the molecule:
1Y is as mentioned above) 9 Such aminoplast resin is characterized by having an amphoteric group represented by
As described in No. 9066, for example, R.

R1-NH-CH2-CB-So, H, or the corresponding aminocarboxylic acid (wherein R1 is 10- or -C00 in the alkyl skeleton)
melamine obtained from melamine and formalin. Conveniently prepared by the method used for etherification of the methylol groups of formaldehyde condensation products. A condensate of urea and formaldehyde, or pen.
Zoguanamine condensed with formaldehyde is similarly reacted with an alcohol having an amphoteric group as described above, and, if desired, with a primary monohydric alcohol at the same time. Due to this reaction, -NHCH20)1, -N(CH2011)2,
-NH-CH2-OR' or -N(CH20R'
)2, etc. (where R' is a compound residue having a lower alkyl or amphoteric group) are mixed.

JP-A-58-129066 discloses that a melamine resin having such amphoteric groups is used as an emulsifier in emulsion polymerization of ethylenically unsaturated monomers, but the melamine resin itself is used as a pigment dispersion resin. Also, no consideration was given to its use as a paint resin.

The present inventors found that among the above aminoplast resins having amphoteric groups, those having a weight average molecular weight of about 900 to 40,000 are extremely useful as resins for dispersing pigments, and that those having a weight average molecular weight of less than 900 are used as pigment dispersing resins. It has been found that the dispersion effect is poor, and those with a molecular weight exceeding 40,000 have poor compatibility with paint resins and are difficult to handle as paints. In addition, melamine and the like are blended into various paints as hardening agents, but since they are generally compatible with acrylic resins, polyester resins, epoxy resins, etc., the pigment dispersion paste of the present invention can be blended into paints using a wide variety of resins. , and has versatility.

The reason why the aminoplast resin having an amphoteric group of the present invention has excellent pigment dispersibility is that it exhibits excellent affinity for basic groups, and also has a structural structure for quinacridone-based neutral pigments. This is thought to be because the A moiety does not show strong affinity for the -NH- group moiety within. Furthermore, it is thought to have a universal effect on the pigment surface. Therefore, it has excellent dispersion stability for a wide variety of pigments.

Furthermore, the aminoplast resin having an amphoteric group of the present invention can contain a methylmethylol group or a butylated methylol group in the molecule due to its manufacturing method, so the aminoplast resin itself can be self-condensed or Three-dimensional crosslinking can be achieved by co-condensation with hydroxyl groups, etc. During such curing, the A 2 moiety in the amphoteric group has a curing accelerating effect, thus achieving low temperature curing. The present inventors have determined that 11 of KOH is required to neutralize the zwitterionic groups in 1 g of aminoblast resin.
It has also been found that especially when the amphoteric group value expressed in 1 g is 2 to 40, the low temperature curability is remarkable.

In any case, the resin for the pigment dispersion paste of the present invention is not only useful for simply dispersing pigments, but also reacts with the base resin of the paint and participates in the formation of the paint film, resulting in strong weather resistance, gloss, and other paint film properties. A coating film with excellent performance can be provided.

Since a resin having amphoteric groups having such characteristics is used, an extremely wide range of pigments can be used in the pigment dispersion paste of the present invention, and they can be selected from any pigments normally used in paints. can be selected. In other words, examples of inorganic pigments include zinc white, titanium oxide, antimony white, iron black, red iron oxide, red lead, cadmium yellow, zinc sulfide, lithopone, barium sulfate, lead sulfate, barium carbonate, lead white, and alumina white. Pigments include azo, polycondensed azo, metal complex azo,
benzimidacilones, phthalocyanines (blue, green), thioindigos, anthraquinones, flavanthrones, indanthrenes, anthrapyridines,
Various pigments of the bilanthrone, isoindolinone, perylene, perinone and quinacridone types are advantageously used.

The blending ratio of the above-mentioned dispersing resin and pigment is not critical and can be selected arbitrarily since it is further diluted with resin or solvent when making a paint, but it is important to consider the economics of manufacturing the dispersion paste,
Considering dispersion efficiency, etc., the ratio is usually 5 to 95% by weight of the resin (solid content) and 95 to 5% by weight of the pigment, and preferably 30 to 70% by weight of the resin (solid content) and 70 to 30% by weight of the pigment. weight%
used at a rate of

The pigment dispersion paste of the present invention comprises the above-mentioned aminoplast resin having an amphoteric group and one or both of the above-mentioned pigments.
If necessary, solvents commonly used in the paint industry, such as toluene, xylene, ester solvents such as Tsurupez 100 and Tsurupez 150, and MEK are mixed.
, MIBK, etc., and use a conventional dispersion machine such as a roll mill dispersion machine, a ball mill dispersion machine, a sand grind mill dispersion machine, a planetary mixer, a high-speed dispersion dispersion machine, etc. Manufactured. Further, in the present invention, it is also possible to use an aqueous solvent.

The dispersion base composition thus obtained exhibits extremely good pigment dispersibility, is excellent in stability during storage, has excellent compatibility with various resins and solvents, and has improved properties such as weather resistance and gloss. It is extremely useful as a pigment dispersion base composition for preparing paints.

The present invention will be explained below with reference to typical production examples and examples of the dispersing resin used in the present invention. In these production examples and examples, parts or percentages are by weight unless otherwise specified.

Synthesis of a new amino resin Synthesis Example 1 Weighed 387 parts of Formit M (manufactured by Koei Chemical ■, 46.5% formaldehyde/methanol solution) and 126 parts of melamine into a four-bottle flask equipped with a stirrer, a reflux condenser, and a thermometer. After carrying out the methylolation reaction at reflux temperature for 10 minutes, 9210 parts of hydroxyethyl tau was added and the reaction was carried out for 10 minutes. After that, the pi was adjusted to 3.5 using hydrochloric acid, and the reaction was carried out under reflux for 10 minutes.
6 parts were added, the reaction was carried out at 60°C for 4 hours, and then concentrated under reduced pressure to adjust the non-volatile content to 60% to obtain amino resin A. Table 1 shows the characteristic values of the resin obtained.

Synthesis Example 2 Using the same apparatus as in Synthesis Example 1, 323 parts of Formit M, 64 parts of methanol, and 126 parts of melamine were weighed out, and a methylolation reaction was performed at reflux temperature for 30 minutes. Then, 40 parts of hydroxyethyl taurine was added, and the mixture was reacted for 10 minutes. I did it.

After that, the pH was adjusted to 4.0 using formic acid, and the reaction was carried out under reflux for 10 minutes. Then, 100 parts of methanol was added and the temperature was raised to 70°C.
The reaction was carried out for 6 hours, and then concentrated under reduced pressure to reduce the nonvolatile content to 60
% to obtain amino resin B. Table 1 shows the characteristic values of the resin obtained.

Synthesis Example 3 Using the same apparatus as Synthesis Example 1, 516 parts of Formite M,
Weigh out 126 parts of melamine, perform a methylolation reaction at reflux temperature for 10 minutes, adjust the pH to 3.0 using dodecylbenzenesulfonic acid, and then add 50 parts of methanol.
The mixture was reacted at 60° C. for 6 hours, and then concentrated under reduced pressure to adjust the nonvolatile content to 80% to obtain amino resin a. Furthermore, 299210.3 parts of hydroxyethyl was added to this resin and the reaction was carried out at 60° C. for 1 hour to obtain amino resin C.

Table 1 shows the characteristic values of the resin obtained.

Synthesis Example 4 Using the same apparatus as in Synthesis Example 1, 355 parts of Formite M, 84 parts of melamine, and 20 parts of urea were weighed, and 1
After carrying out the methylolation reaction for 0 minutes, the pH was adjusted to 3.2 using para-toluenesulfonic acid, and then 110 parts of methanol was added and the reaction was carried out at 60°C for 4 hours. After that, it was concentrated under reduced pressure to remove non-volatile components. It was adjusted to 80%. Furthermore, 3 parts of hydroxyethylaminodiethanesulfonic acid was added to this resin, and the reaction was carried out at 60°C for 1 hour. Furthermore, 148 parts of n-butanol was added and the reaction was carried out at 60°C for 2 hours, and then concentrated under reduced pressure. The content was adjusted to 80% to obtain an amino resin resin. Table 1 shows the characteristic values of the resin obtained.

Synthesis Example 5 Using the same apparatus as in Synthesis Example 1, 387 parts of Formit M and 187 parts of benzoguanamine were weighed out, adjusted to pH 8.5 with triethylamine, reacted for 10 minutes at reflux temperature, and prepared with 15 parts of hydroxyethylaminoethanecarboxylic acid. was added, further adjusted to pH = 3.8 with phosphoric acid and reacted,
After that, 126 parts of methanol was added and the reaction was carried out at 60°C for 4 hours, and then concentrated under reduced pressure to adjust the non-volatile content to 80%.
Amino resin E was obtained. Table 1 shows the characteristic values of the resin obtained.

Synthesis Example 6 Same as Synthesis Example 2, 323 parts of Formite M, 6 parts of methanol
Weigh out 4 parts and 126 parts of melamine, and add 30 parts at reflux temperature.
After carrying out the methylol reaction for one minute, 52 parts of hydroxyethyl taurine was added and the reaction was carried out for 10 minutes. After that, the pi (pi) was adjusted to 4.0 using formic acid, and after reacting for 10 minutes under reflux, 100 parts of methanol was added, and the
The reaction was carried out for a period of time, and then concentrated under reduced pressure to adjust the nonvolatile content to 60% to obtain an amino resin.

Unreacted amphoteric ionic compounds were precipitated in the resulting resin. Table 1 shows the characteristic values of the resin obtained.

Synthesis Example 7 Using the same apparatus as Synthesis Example 1, 387 parts of Formite M and 126 parts of melamine were weighed out, and a methylolation reaction was carried out at reflux temperature for 10 minutes, and then the pn was adjusted to 4.5 using formic acid for 10 minutes. After that, 126 parts of methanol was added, the reaction was carried out at 60°C for 4 hours, and then concentrated under reduced pressure.
The nonvolatile content was adjusted to 80%. 12 parts of hydroxyethyl taurine was added thereto, and the mixture was reacted at 60° C. for 2 hours to obtain amino resin C. Table 1 shows the characteristic values of the resin obtained.

Synthesis Example 8 Using the same apparatus as in Synthesis Example 1, 323 parts of Formit M, 64 parts of methanol, and 126 parts of melamine were weighed out, and a methylolation reaction was carried out at reflux temperature for 30 minutes. Then, 12 parts of hydroxyethyltaurine was added, and the mixture was reacted for 10 minutes. After the reaction, the pH was adjusted to 3.2 using hydrochloric acid and reacted for 10 minutes, then 100 parts of methanol was added and the reaction was carried out at reflux temperature for 6 hours, and then concentrated under reduced pressure to reduce the non-volatile content to 60%. and amino resin d was obtained. The characteristic value of the obtained resin is the first
Shown in the table.

Example 1 Amino resin A having zwitterionic groups obtained in Synthesis Example 1 above
Pigment dispersion was performed using the following dispersion blending to create a carbon black dispersion paste, and then a carbon black paint was created by dissolving and blending.

The obtained dispersion paste was flow-coated onto a glass plate, and the 20° specular gloss (Murakami gloss needle GM-3H type) of this coating film was measured to evaluate pigment dispersibility. Add this paint solution to 2
3 seconds/Adjust to #4 Ford Cup (20℃), 5PC
The above-mentioned viscosity-adjusted paint was spray-painted on a coating film that had been subjected to zinc phosphate treatment, cationic electrodeposition, and intermediate coating on a -1 dull steel plate, and after a certain period of time, it was baked at 140'C for 30 minutes. The test results of the obtained coating film are shown in Table 2. As shown in Table 2, it was shown to have excellent dispersibility (20° specular gloss), as well as excellent finished appearance, storage stability, and physical properties of the coating film after being made into a paint.

300.55 Example 2 The novel amino resin A obtained in Synthesis Example 1 was subjected to pigment dispersion using the following dispersion blending to create a Shanin Blue dispersion paste, and then a Shanin Blue paint was created by dissolving and blending. Thereafter, it was flow coated onto a glass plate in the same manner as in Example 1, and the same dispersibility and coating tests were conducted and evaluated.

195.55 Example 3 Pigment dispersion was performed on the novel amino resin A obtained in Synthesis Example 1 using the following dispersion blend to create a red dispersion paste,
A red paint was then prepared by melt blending. Thereafter, it was flow coated onto a glass plate in the same manner as in Example 1, and the same dispersibility and coating tests were conducted and evaluated.

105.05 Meeting 5... Shinkasha Red Y manufactured by DuPont■ (RT-7590) Example 4~
6 Each primary color paint was created by replacing the novel amino resin A in the paint formulation tables of Examples 1 to 3 with the novel amino resin B obtained in Synthesis Example 2. Each of the obtained dispersion pastes and coating liquids was flow-coated onto a glass plate in the same manner as in Example 1, and 20° specular gloss and each coating film test were conducted. The results are shown in Table 2.

Examples 7 to 9 The new amine resin A in the paint formulation tables of Examples 1 to 3 was replaced with the new amino resin C obtained in Synthesis Example 3 to create paints of each primary color. Each of the obtained dispersion pastes and coating liquids was flow-coated onto a glass plate in the same manner as in Example 1, and 20° specular gloss measurement and each coating film test were conducted and evaluated. The results are shown in Table 2.

Example 10~! 2. The novel amino resin A obtained in Synthesis Example 4 was substituted for the novel amino resin A in the paint formulation tables of Examples 1 to 3 to prepare paints of each primary color. The obtained dispersion pastes and coating liquids were flow-coated onto a glass plate in the same manner as in Example 1, and 20° specular gloss measurements and coating film tests were performed. The results are shown in Table 2.

Examples 13 to 15 The novel amino resin A in the paint formulation tables of Examples 1 to 3 was replaced with the novel amino resin E obtained in Synthesis Example 5 to create paints of each primary color. The obtained dispersion pastes and coating liquids were flow-coated onto a glass plate in the same manner as in Example 1, and 20° specular gloss measurements and coating film tests were performed. The results are shown in Table 2.

Comparative Examples 1 to 12 New amino resin A in the paint formulation table of Examples 1 to 3 was substituted with amino resins a, b, and c obtained in Synthesis Example 3 and Synthesis Examples 6 to 8.
Dispersion pastes and coating liquids were prepared in place of d and d. As in Example 1, flow coating was performed on a glass plate, 20" specular gloss measurement and coating test were performed, and the results are shown in Table 2. As shown in Table 2, 20" specular gloss 1, appearance , 60° specular gloss, and storage stability are all poor, a,
In case b, the physical properties of the coating film are also poor.

Examples 16 to 18 Each dispersion paste prepared in Examples 1 to 3 was used in Examples 1 to 3.
Under the same formulation conditions as above, using acrylic resin (II) instead of polyester resin (I), each coating solution was prepared and the physical properties of the coating film were evaluated in the same manner. The results are shown in Table 3.

Examples 19 to 21 Each of the dispersion pastes prepared in Examples 1 to 3 was used in Examples 1 to 3.
Under the same formulation conditions as above, each paint solution was prepared using epoxy resin (III) in place of polyester resin (1), and the physical properties of the paint film were evaluated in the same manner. The results are shown in Table 3.

Example 22 Using the same amino resin as in Example 1O, pigment was dispersed according to the following dispersion mixture to create a carbon black dispersion paste, and the paste was poured onto a glass plate to measure the specular gloss at 20° and the dispersibility was evaluated. evaluated. The gloss value was 88, and when the particle size was checked using the Hegemann scale, no coarse particles were observed, and the product is applicable to dispersion of water-based paint systems.

Example 23 Using the same amino resin as in Example 1O, pigment was dispersed according to the following dispersion formulation to create a Shanin Blue dispersion paste, which was flow-coated on a glass plate for 20° to measure its specular gloss.
Dispersibility was evaluated. The gloss value was 92, and when the particle size was checked using the Hegeman scale, no coarse particles were observed.

QIll, 75 Takashi 6...Fast Gen Blue BB manufactured by Dainippon Ink ■ Comparative Example 13.14 In place of the new amino resins in Examples 22 and 23, amino resin a was used and dispersed in the same manner, but the dispersion did not occur. I couldn't.

(Hereinafter referred to as the margin); S o (Note 1) Outside finish vm: The finished appearance was evaluated based on the glossiness and texture according to the following criteria.

◎...Very good ○...Good Δ...Slightly poor ×...Poor (Note 2) 60" specular gloss: 60" reflectance with Murakami glossy needle GM-3H type (Note 3)
Pencil hardness: Judgment was made based on the highest hardness until no scratches occurred with a Mitsubishi Uni pencil.

(Note 4) Acid resistance: N/10 51! Drop, temperature 2
After leaving it at 0℃ for 1 hour, wash with water, the painted surface will wrinkle and swell.
Observed discoloration.

(Note 5) Alkali resistance: Drop 5 mj of N/10 Na011 in the same manner as above,
After being left in a drying oven at a temperature of 55°C for 4 hours, it was washed with water and the painted surface was observed for wrinkles, blisters, and discoloration.

(Note 6) SWOM: Evaluate the gloss retention rate after 2000 hours using a sunshine weather meter.

(Note 7) Storage stability: The coating solution was evaluated by the state of sedimentation and aggregation after being left at 40°C for one month.

O...Very good Δ...Good ×...Poor patent application agent Patent Attorney ± 1A Takeo Fuji

Claims (2)

[Claims] (1) The weight average molecular weight is 900 to 40,000, and the molecule contains the formula -N^■-R-Y^■ (wherein R is C_1 to C_6 alkylene or phenylene, which may have a substituent; Y ^■ consists of an aminoplast resin having an amphoteric group represented by -COO^- or -SO_3^-, a pigment, and a solvent, and the solid content weight ratio of the aminoplast resin and the pigment is 5/95 to 95/ 5. A pigment dispersion paste characterized by: (2) K required for aminoplast resin having amphoteric groups to neutralize the amphoteric groups contained in 1 g of resin
The pigment dispersion paste according to claim 1, which is a resin having an amphoteric group value expressed in mg of OH within a range of 2 to 40.