JP7510169B2 - Dispersants for non-aqueous coating agents and non-aqueous coating agents - Google Patents

Description

The present invention relates to a dispersant for a non-aqueous coating agent and a non-aqueous coating agent.

"A polymeric dispersant for inorganic pigments, which contains a copolymer containing 1% by mass or more and 45% by mass or less of structural units (a) represented by formula (1) and 55% by mass or more and 99% by mass or less of structural units (b) represented by formula (2) among all structural units, and is used in a non-aqueous solvent.

［式（１）中、Ｒ^１、Ｒ^２、及びＲ^３は同一又は異なり、水素原子、メチル基又はエチル基を示し、Ｍは水素原子又は陽イオンを示す。］

[In formula (1), R ¹ , R ² , and R ³ are the same or different and represent a hydrogen atom, a methyl group, or an ethyl group, and M represents a hydrogen atom or a cation.]

［式（２）中、Ｒ^４、Ｒ^５、Ｒ^６及びＲ^８は同一又は異なり、水素原子、メチル基又はエチル基を示し、Ｒ^７は炭素数２以上４以下の直鎖又は分岐鎖のアルキレン基を示し、Ｘ^１は酸素原子又はＮＨを示し、ｎは－Ｒ^７－Ｏ－基の平均付加モル数であって５０を超え１４０以下の数を示す。］」が知られている(特許文献１）。

[In formula (2), R ⁴ , R ⁵ , R ⁶ and R ⁸ are the same or different and represent a hydrogen atom, a methyl group or an ethyl group, R ⁷ represents a linear or branched alkylene group having from 2 to 4 carbon atoms, X ¹ represents an oxygen atom or NH, and n represents the average number of moles of -R ⁷ -O- groups added, which is a number greater than 50 and not greater than 140] is known (Patent Document 1).

International Publication WO2015/041226 Pamphlet

Conventional polymeric dispersants for inorganic pigments, when used in non-aqueous coating agents, have problems such as poor dispersibility of colored pigments such as carbon black, leading to the formation of aggregates on the surface of the coating film formed and reduced gloss. The object of the present invention is to provide a dispersant that has excellent dispersibility of colored pigments when used in non-aqueous coating agents.

The dispersant for non-aqueous coating agents of the present invention contains a copolymer (X) composed of (meth)acrylic acid (A) units and (meth)acrylic acid alkoxy polyoxyethylene ester (B) units, and the number of repeating oxyethylene units contained in the (meth)acrylic acid alkoxy polyoxyethylene ester (B) units is 5 to 30, and the content of (meth)acrylic acid (A) units is 50 to 70 mol % and the content of (meth)acrylic acid alkoxy polyoxyethylene ester (B) units is 50 to 30 mol % based on the number of moles of the (meth)acrylic acid (A) units and the (meth)acrylic acid alkoxy polyoxyethylene ester (B) units.

The gist of the non-aqueous coating agent of the present invention is that it contains the above-mentioned dispersant for non-aqueous coating agents, a non-aqueous solvent, a pigment, and a binder.

When the dispersant for non-aqueous coating agents of the present invention is applied to non-aqueous coating agents, it has excellent dispersibility for colored pigments such as carbon black, and there are no problems such as the formation of aggregates on the surface of the coating film formed or a decrease in gloss.

The non-aqueous coating agent of the present invention uses the above-mentioned dispersant for non-aqueous coating agents, and therefore has excellent dispersibility for colored pigments such as carbon black, and there are no problems such as the formation of aggregates on the surface of the coating film formed or a decrease in gloss.

"(Meth)acrylic..." means "acrylic..." and "methacrylic..." (hereinafter the same). In other words, the (meth)acrylic acid (A) unit includes an acrylic acid unit and a methacrylic acid unit. Note that (meth)acrylate units are not included, but may be included to the extent that does not impair the effects of the present invention.

The content (mol%) of (meth)acrylic acid (A) units is preferably 50 to 70, more preferably 52 to 68, and particularly preferably 54 to 66, based on the number of moles of (meth)acrylic acid (A) units and (meth)acrylic acid alkoxypolyoxyethylene ester (B) units. If it is within this range, the dispersibility will be even better.

The (meth)acrylic acid alkoxy polyoxyethylene ester (B) unit includes an acrylic acid alkoxy polyoxyethylene ester unit and a methacrylic acid alkoxy polyoxyethylene ester unit. Note that the polyoxyethylene chain contained in the (meth)acrylic acid alkoxy polyoxyethylene ester (B) unit may contain oxyalkylenes having 3 to 4 carbon atoms other than oxyethylene (oxypropylene and oxybutylene), etc., within the scope that does not impair the effects of the present invention.

From the viewpoint of dispersibility, the number of repeating oxyethylene units is preferably 5 to 30, more preferably 7 to 25, and particularly preferably 9 to 23.

The alkoxy group in the alkoxy polyoxyethylene ester includes an alkyloxy group having 1 to 30 carbon atoms, and linear alkyloxy groups and branched alkyloxy groups can be used.

Examples of linear alkyloxy groups include methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy, n-hexyloxy, n-heptyloxy, n-octyloxy, n-nonyloxy, n-decyloxy, n-undecyloxy, n-dodecyloxy, n-tridecyloxy, n-tetradecyloxy, n-pentadecyloxy, n-hexadecyloxy, n-heptadecyloxy, n-octadecyloxy, n-nonadecyloxy, n-icosyloxy, n-henicosyloxy, n-docosyloxy, n-tricosyloxy, n-tetracosyloxy, n-heptacosyloxy, n-hexacosyloxy, n-heptacosyloxy, n-octacosyloxy, n-nonacosyloxy, and n-triaconyloxy.

Examples of branched alkyloxy groups include isopropyloxy, isobutyloxy, t-butyloxy, isopentyloxy, neopentyloxy, isohexyloxy, 2-ethylhexyloxy, isotridecyloxy, isooctadecyloxy, and isotriaconyloxy.

Among these, from the viewpoint of dispersibility, linear alkyloxy groups are preferred, more preferably linear alkyloxy groups having 1 to 18 carbon atoms, and particularly preferably methoxy, ethoxy, and octadecyloxy.

The content (mol%) of (meth)acrylic acid alkoxy polyoxyethylene ester (B) units is preferably 30 to 50, more preferably 32 to 48, and particularly preferably 34 to 46, based on the number of moles of (meth)acrylic acid (A) units and (meth)acrylic acid alkoxy polyoxyethylene ester (B) units. If it is within this range, the dispersibility will be even better.

The copolymer (X) may contain, in addition to (meth)acrylic acid (A) and (meth)acrylic acid alkoxypolyoxyethylene ester (B), another ethylenically unsaturated monomer (C) as a constituent monomer.

The other ethylenically unsaturated monomer (C) is not particularly limited as long as it can be copolymerized with (meth)acrylic acid (A) and (meth)acrylic acid alkoxy polyoxyethylene ester (B), and known ethylenically unsaturated monomers (for example, JP 2014-105222 A) can be used, including ethylenically unsaturated carboxylic acids (not including (meth)acrylic acid), olefins, ethylenically unsaturated nitriles, and ethylenically unsaturated amides.

When other ethylenically unsaturated monomer (C) units are contained, the content (mol %) of other ethylenically unsaturated monomer (C) units is about 0.1 to 20 (preferably 0.5 to 15, more preferably 1 to 10) based on the number of moles of (meth)acrylic acid (A) units and (meth)acrylic acid alkoxy polyoxyethylene ester (B) units, but from the viewpoint of dispersibility, it is most preferable that no other ethylenically unsaturated monomer (C) units are contained.

From the viewpoint of dispersibility, the weight average molecular weight (Mw) of the copolymer (X) is preferably 5,000 to 100,000, more preferably 7,000 to 70,000, and particularly preferably 10,000 to 50,000.

The weight average molecular weight (Mw) can be measured by gel permeation chromatography (GPC) (for example, under the following conditions):

Measuring device: HLC-8220 (Tosoh Corporation)
Column: Guard column HXL-H, TSKgel SuperHZ4000, TSKgel SuperHZ3000, TSKgel SuperHZ2000 and TSKgel SuperHZ2000 (Tosoh Corporation) connected in series Detector: RI (differential refractometer)
Data processing: SC-8010 (Tosoh Corporation)
Column temperature: 40°C
Solvent: Tetrahydrofuran Flow rate: 1.0 ml/min Standard material: TSKgel standard polystyrene (Tosoh Corporation)
Sample: 1% by weight tetrahydrofuran solution

The copolymer (X) can be obtained by using a conventional method for polymerizing vinyl monomers (for example, the method described in Patent Document 1). As the polymerization method, bulk polymerization, solution polymerization, etc. can be applied, and from the viewpoint of productivity, etc., solution polymerization is preferred.

The dispersant for non-aqueous coating agents of the present invention may contain additives (antifoaming agents, wetting agents, etc.) and/or solvents in addition to the copolymer (X).

Examples of the defoaming agent include Dappo SN348 and SN359 (San Nopco Ltd.), and examples of the wetting agent include Nopcol W-2990 (San Nopco Ltd.). Examples of the solvent include 2-propanol, butyl acetate, methyl isobutyl ketone, ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, and polyethylene glycol monobutyl ether (the polymerization solvent used in the production of copolymer (X) may be left as it is).

The dispersant for non-aqueous coating agents of the present invention is suitable for non-aqueous coating agents, which include non-aqueous paints, non-aqueous pigment pastes, and non-aqueous inks.

The non-aqueous coating agent preferably contains a dispersant for the non-aqueous coating agent, a non-aqueous solvent, a pigment, and a binder.

There are no restrictions on non-aqueous solvents as long as they are solvents other than water, and examples of such solvents include methanol, ethanol, 2-propanol, toluene, xylene, N-methylpyrrolidone, terpineol, mineral spirits, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, and propylene glycol monobutyl ether (solvents that contain as little water as possible are preferred, although they may contain water as an impurity). These may be used alone or in combination.

There are no limitations on the pigments as long as they are used in non-aqueous coating agents. Examples of organic color pigments include phthalocyanine blue, quinacridone red, isoindoline yellow, and disazo yellow. Examples of inorganic color pigments include carbon black, acetylene black, iron oxide (red, yellow, black), chromium oxide (dark green), and chromium hydroxide (blue-green). Examples of inorganic white pigments include titanium oxide, barium titanate, zinc oxide, and satin white. Examples of inorganic body pigments include calcium carbonate, barium sulfate, talc, kaolin, and mica. These may be used alone or in combination.

There are no limitations on the binder as long as it is one that can be used in non-aqueous coating agents, and examples of the binder include alkyd resin, melamine resin, acrylic resin, epoxy resin, epoxy ester resin, urethane resin, polyester resin, rosin ester resin, carbamine resin, vinyl acetate resin, silicone resin, fluororesin, polyvinyl alcohol resin, polyvinyl butyral resin, and vinyl chloride resin. These may be used alone or in combination.

When the dispersant for non-aqueous coating agents of the present invention is applied to a non-aqueous coating agent, the content (wt%) of the dispersant for non-aqueous coating agents is preferably 0.01 to 50, more preferably 0.1 to 30, based on the weight of the pigment. Within this range, the dispersibility is further improved.

In the following description, unless otherwise specified, "parts" means "parts by weight" and "%" means "% by weight".
Example 1
While stirring 200 parts of isopropyl alcohol at 80 ° C., a monomer solution consisting of 39 parts (0.54 parts by mole) of acrylic acid, 499 parts (0.46 parts by mole) of methoxypolyoxyethylene acrylate (repeating unit of oxyethylene: 23) ester and 480 parts of isopropyl alcohol, and a polymerization initiator solution consisting of 5 parts (0.02 parts by mole) of 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate and 20 parts of isopropyl alcohol were dropped at a constant rate from separate dropping lines over 3 hours, and after the end of the dropping, the temperature was kept at 80 ° C. for 5 hours. Thereafter, the isopropyl alcohol was removed under reduced pressure to obtain a dispersant (1) for non-aqueous coating agents of the present invention [acrylic acid (54 mol%)-methoxypolyoxyethylene acrylate (repeating unit of oxyethylene: 23) ester (46 mol%) copolymer (x1)]. The weight average molecular weight of the copolymer (x1) was 15,000.

Example 2
While stirring 100 parts of isopropyl alcohol at 80°C, a monomer solution consisting of 48 parts (0.66 mol parts) of acrylic acid, 369 parts (0.34 mol parts) of methoxypolyoxyethylene acrylate (repeating unit of oxyethylene: 23) ester, and 380 parts of isopropyl alcohol, and a polymerization initiator solution consisting of 0.5 parts (0.001 mol parts) of (2-ethylhexanoyl)(t-butyl)peroxide and 20 parts of isopropyl alcohol were dropped at a constant rate from separate dropping lines over 3 hours, and after the end of the dropping, the temperature was kept at 80°C for 5 hours. Thereafter, the isopropyl alcohol was removed under reduced pressure to obtain a dispersant (2) for non-aqueous coating agents of the present invention [acrylic acid (66 mol%)-methoxypolyoxyethylene acrylate (repeating unit of oxyethylene: 23) ester (34 mol%) copolymer (x2)]. The weight average molecular weight of the copolymer (x2) was 30,000.

Example 3
A dispersant for a nonaqueous coating agent (3) [acrylic acid (54 mol%)-methoxypolyoxyethylene acrylate (oxyethylene repeat unit: 23) ester (46 mol%) copolymer (x3)] of the present invention was obtained in the same manner as in Example 1, except that the amount of "isopropyl alcohol" was changed from 200 parts to 100 parts and the amount of "1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate" was changed from 5 parts (0.02 mol parts) to 1 part (0.004 mol parts). The weight average molecular weight of the copolymer (x3) was 50,000.

Example 4
A dispersant for non-aqueous coating agents (4) [methacrylic acid (54 mol%)-methacrylic acid octadecyloxypolyoxyethylene (oxyethylene repeat unit: 9) ester (46 mol%) copolymer (x4)] of the present invention was obtained in the same manner as in Example 1, except that "39 parts (0.54 mol) of acrylic acid" was changed to "46 parts (0.54 mol) of methacrylic acid" and "499 parts (0.46 mol) of methoxypolyoxyethylene acrylate (oxyethylene repeat unit: 23) ester" was changed to "229 parts (0.46 mol) of octadecyloxypolyoxyethylene methacrylate (oxyethylene repeat unit: 9) ester" The weight average molecular weight of the copolymer (x4) was 10,000.

Example 5
A dispersant for non-aqueous coating agents (5) [acrylic acid (54 mol%)-ethoxypolyoxyethylene acrylate (oxyethylene repeat unit: 23) ester (46 mol%) copolymer (x5)] of the present invention was obtained in the same manner as in Example 1, except that "methoxypolyoxyethylene acrylate (oxyethylene repeat unit: 23) ester 499 parts (0.46 mol)" was changed to "ethoxypolyoxyethylene acrylate (oxyethylene repeat unit: 23) ester 505 parts (0.46 mol)". The weight average molecular weight of the copolymer (x5) was 16,000.

Comparative Example
A polymer dispersant solution was obtained based on Example 1 described in Patent Document 1. Then, ethanol was removed under reduced pressure to obtain a comparative dispersant [methacrylic acid (50 mol%)-methacrylic acid methoxypolyoxyethylene (oxyethylene repeating unit: 60) ester (7 mol%)-methyl methacrylate (43 mol) copolymer (y5)]. The weight average molecular weight of the copolymer (y5) was 12,000.

<Evaluation 1> Dispersibility of inorganic colored pigment (carbon black) 324 parts of Beckolite M-6402-50 (50% organic solvent solution of polyester resin, DIC Corporation, "Beckolite" is a registered trademark of DIC Corporation), 1 part of defoamer (Dappo SN-359, San Nopco Ltd., "Dappo" is a registered trademark of San Nopco Ltd.), 70 parts of MA-100 (carbon black, Mitsubishi Chemical Corporation), 21 parts of any of the dispersants prepared in Examples 1 to 5 and Comparative Examples, and 300 parts of glass beads (diameter 2 mm) were placed in a glass bottle, shaken with a paint shaker for 1 hour, and the glass beads were filtered off to obtain a color paste for evaluation. In addition, a color paste for evaluation (blank) was obtained in the same manner as above except that no dispersant was used.

Next, 15 parts of any of the color pastes for evaluation, 48 parts of Beckolite M-6402-50 (a 50% organic solvent solution of polyester resin, DIC Corporation), and 12 parts of Cymel 303LF (a melamine resin, Allnex Corporation; "Cymel" is a registered trademark of Allnex Netherlands B.V.) were uniformly mixed to prepare non-aqueous coating agents for evaluation.

Each non-aqueous coating agent for evaluation was applied to a glass plate using a 6-mil applicator and baked at 240°C for 30 seconds to prepare a coating film for evaluation. The gloss value (60°) of each coating film for evaluation was measured using a gloss meter and is shown in the table below. The higher this value, the better the dispersibility.

<Evaluation 2> Dispersibility of inorganic white pigment (titanium oxide) 224 parts of Beckolite M-6402-50 (50% organic solvent solution of polyester resin, DIC Corporation), 370 parts of Typek R-820 (titanium oxide, Ishihara Sangyo Kaisha, Ltd.; "Typek" is a registered trademark of Ishihara Sangyo Kaisha, Ltd.), 0.37 parts of any of the dispersants prepared in Examples 1 to 5 and Comparative Examples, 2 parts of a defoamer (Dappo SN-359, San Nopco Ltd.) and 600 parts of glass beads (diameter 2 mm) were placed in a glass bottle and shaken for 1 hour with a paint shaker. Then, 135 parts of Beckolite M-6402-50 (50% organic solvent solution of polyester resin, DIC Corporation), Amidya A non-aqueous coating agent for evaluation was obtained by adding 45 parts of Amidea L-105-60 (amino resin "a resin obtained by addition and condensation reaction of an amino compound such as melamine, benzoguanamine or urea with formaldehyde, and etherifying it with an aliphatic monohydric alcohol," DIC Corporation, and "Amidea" is a registered trademark of the company), 22 parts of Amidea L-117-60 (amino resin, DIC Corporation), 100 parts of toluene and 100 parts of cyclohexanone and mixing uniformly, and then filtering out the glass beads. A non-aqueous coating agent for evaluation (blank) was also obtained in the same manner as above, except that no dispersant was used.

Each non-aqueous coating agent for evaluation was applied to a glass plate using a 6-mil applicator and baked at 240°C for 30 seconds to prepare a coating film for evaluation. The gloss value (60°) of each coating film for evaluation was measured using a gloss meter and is shown in the table below. The higher this value, the better the dispersibility.

As shown above, the dispersant for non-aqueous coating agents of the present invention has superior dispersibility of inorganic colored pigments compared to the comparative dispersant, and furthermore, the dispersant for non-aqueous coating agents of the present invention also has superior dispersibility of inorganic white pigments compared to the comparative dispersant.

Claims (2)

The copolymer (X) comprises a (meth)acrylic acid (A) unit and a (meth)acrylic acid alkoxy polyoxyethylene ester (B) unit,
The (meth)acrylic acid alkoxy polyoxyethylene ester (B) unit contains 5 to 30 oxyethylene repeating units,
A dispersant for non-aqueous coating agents, characterized in that the content of (meth)acrylic acid (A) units is 50 to 70 mol % and the content of (meth)acrylic acid alkoxypolyoxyethylene ester (B) units is 50 to 30 mol % based on the number of moles of (meth)acrylic acid (A) units and (meth)acrylic acid alkoxypolyoxyethylene ester (B) units. A non-aqueous coating agent comprising the dispersant for non-aqueous coating agents according to claim 1, a non-aqueous solvent, a pigment, and a binder.