JP4254292B2 - Aqueous pigment dispersant and method for producing the same - Google Patents

Description

【００４３】
＜顔料分散剤の評価方法＞
前述のようにして得られた顔料分散剤Ｓ１〜Ｓ４、および共重合体（Ｂ）が溶解できなかった比較例２、４、５、９を除く比較例１、３、６、７、８の比較顔料分散剤ＲＳ１、ＲＳ３、ＲＳ６、ＲＳ７、ＲＳ８の各顔料分散剤の評価を下記のように行った。
【００４４】
１．酸化チタン分散インキによる評価
（１）試験インキの作成
１７％固形分濃度の各顔料分散剤を１１５．２ｇ（固形分１９．６ｇ）、レットダウンエマルジョンＪ−１４０Ａ （製品名、星光化学工業（株）製）を６５．２ｇ（固形分２６．１ｇ）、酸化チタン（石原産業（株）製、商品名：ＴＩＰＡＱＵＥ ＣＲ−９０）を１９．６ｇ（全固形比［ｗｔ％］、樹脂ワニス：Ｊ−１４０Ａ：酸化チタン＝３０：４０：３０）、ガラスビーズ３００ｇ、およびシリコン系消泡剤１ｇを混合し、ペイントシェーカーにて３０分振とう後、上澄みを採取し、試験インキであるＩ１〜Ｉ４および比較用試験インキＲＩ１、ＲＩ３、ＲＩ６、ＲＩ７、ＲＩ８を作成した。Ｉ１〜Ｉ４およびＲＩ１，ＲＩ３、ＲＩ６、ＲＩ７、ＲＩ８の固形分および粘度を表２に示す。
【００４５】
【表２】

【００４６】
（２）試験インキの顔料分散安定性評価
・分散安定性試験：各試験インキを別々のガラス瓶に同量づつとり、分散インキ静置直後からの分離・沈降具合を、下記基準にて目視評価した。その結果を表３に示す。
◎：２ヶ月経過後も分離・沈降なく、非常に安定、
○：２ヶ月経過までには分離・沈降見られるが、１ヶ月以上安定、
△：１ヶ月経過までには分離・沈降見られるが、２週間以上安定、
×：分散直後〜２週間以内に分離・沈降見られる。
【００４７】
（３）試験インキのフィルム展色評価
各試験インキをＮｏ．８のバーコーターを用いてＰＥＴフィルム上に展色し、光沢、隠蔽性、密着性、外観などについて比較確認した。その結果を表３に示す。
・光沢：グロスメーターにて６０°グロスを測定した。
・隠蔽性：フィルム上に形成された印刷面の隠蔽性を下記基準にて目視評価した。
○：下地のフィルム層が全く見られない、
△：フィルム層が若干透けて見える、
×：フィルム層の裏側まで透けて見える、もしくはハジキが見られ、均一に塗布できない。
【００４８】
・密着性：セロハンテープによる剥離試験を行ない、密着性を下記基準にて目視評価した。
◎：全く剥離していない、
○：僅かに剥離している、
△：かなり剥離している、
×：ほとんど剥離している。
・外観：フィルム上に形成された印刷面の仕上がり外観を、艶感、発色性、泳ぎなどから総合的に調査し、次の基準で評価した。
○：良好、△：不良、×：著しく不良。
【００４９】
【表３】

【００５０】
2．マイカ（白雲母）分散による評価
（１）マイカ分散液の作成
１７％固形分濃度の各サンプルを固形比１６％、マイカ（製品名Ａ−３１：山口雲母工業所製）３０％、石油樹脂（東邦化学工業（株）製、商品名ＱＭＥ−６０）５４％、で混合し、トータル組成中固形分４３％のマイカ分散液、Ｄ１〜Ｄ４およびＲＤ１、ＲＤ３、ＲＤ６、ＲＤ７、ＲＤ８を作成した。得られたＤ１〜Ｄ４およびＲＤ１、ＲＤ３、ＲＤ６、ＲＤ７、ＲＤ８の粘度およびｐＨを表４に示す。
【００５１】
（２）マイカ分散液の分散安定性評価
・分散安定性試験：各マイカ分散液を別々のガラス瓶に同量づつとり、常温にて静置して、分散インキ静置直後からの分離具合や、上下層の粘度差を、下記基準にて分散安定性を目視評価した。その結果を表４に示す。
○：１ヶ月経過後も分離や上下層の粘度差も見られることなく安定、
△：１ヶ月経過までには分離や上下層の粘度差見られるが、２週間以上安定、
×：分散直後〜２週間以内に分離や上下層の粘度差見られる。
【００５２】
【表４】

【００５３】
上記の結果から明らかなように、本発明に係る顔料分散剤は、本発明で規定する構成により、分散安定性、展色性および顔料分散性において同等または良好な結果が得られ、特に顔料分散安定性、光沢において著しく優れていることがわかった。
【００５４】
【発明の効果】
本発明の顔料分散剤は、臭気の問題がなく、製造の煩雑さを伴うことないのに加え、従来の技術では適わなかった完全水系、ノンＶＯＣで、かつ構造制御された共重合体アルカリ水溶液を安定に製造することができる。本発明によって顔料分散安定性、光沢および発色性が著しく向上された顔料分散剤を得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aqueous pigment dispersant used to disperse various inorganic powders and organic / inorganic pigments used in aqueous printing inks, paints, inkjet inks, and coating agents.
[0002]
[Prior art]
Conventional polymers such as styrene / acrylic resins used as pigment dispersants for conventional water-based printing inks are generally randomly copolymerized.
[0003]
On the other hand, it is reported that a polymer whose structure is controlled by polymerizing a hydrophobic monomer and a hydrophilic monomer in a block or graft manner is superior in pigment dispersibility to a polymer obtained by random copolymerization, etc. It is made in. However, such a structure-controlled polymer is difficult to industrialize. For example, in the living polymerization method using cationic polymerization or anionic polymerization, the use of an acid monomer is limited and the reaction system is often water-free. There are problems such as sufficient dehydration of solvents, monomers, etc., low yield, inclusion of halogenated compounds, and coloring due to residual metal catalyst. The polymerization method by the atom transfer radical polymerization (ATRP) method can be carried out in an aqueous system, but there are problems similar to those described above, such as the halogen compound content, work complexity, and low yield.
[0004]
In addition, when these polymers whose structure is controlled are completely desolvated and then saponified with alkaline water, so-called completely aqueous, gelation in the desolvation step by heating, or in alkaline water There are problems such as hydrolysis of the block (graft) portion that occurs during saponification. For example, the former specifically uses glycidyl (meth) acrylate, ethylene glycol di (meth) acrylate or the like as a graft site, and the latter specifically uses a chain transfer agent having a functional group such as mercaptoacetic acid or mercaptoethanol. These polymers are difficult to obtain an aqueous aqueous solution by completely removing the solvent.
[0005]
Patent Documents 1 to 3 as other structurally controlled polymers include a method for producing a graft polymer composed of vinyl monomers using 2,4-diphenyl-4-methyl-1-pentene which is an α-methylstyrene dimer, and a methacryloyl group. A method for producing a block polymer containing 70 mol% or more of a monomer having a diol is disclosed. However, these are solution-polymerized, then diluted with water as they are without solvent removal, and then subjected to alkali saponification, and are not completely aqueous solutions.
[0006]
In recent years, from the viewpoint of protecting the global environment, inks or paints with a low volatile organic compound content (VOC) have been required, and in the future, a completely water-based, non-VOC type that does not contain any solvent will be required. It is thought that it will be done. Therefore, a proposal of an aqueous pigment dispersant that does not contain a solvent and has excellent pigment dispersibility is desired.
[Patent Document 1]
Japanese Unexamined Patent Publication No. 7-2954
[Patent Document 2]
JP 2000-169531 A
[Patent Document 3]
Japanese Patent Laid-Open No. 2002-129093
[Non-Patent Document 1]
Schaller C., Dirnberger K., Schauer T., "Eisenbach CD Progress in Organic Coatings", 1999, 35, p63-67
[0007]
[Problems to be solved by the invention]
The present invention provides an aqueous pigment dispersant excellent in pigment dispersibility and a method for producing the same.
[0008]
[Means for Solving the Problems]
In the present invention, the first monomer component containing 30% by weight or more of acrylic acid is mixed with 15 to 50% by weight of 2,4-diphenyl-4-methyl-1-pentene (hereinafter referred to as “MSD”) with respect to the first monomer component. A copolymer obtained by polymerizing a second monomer component containing 80% by weight or more of a hydrophobic monomer in the presence of a copolymer (A) obtained by polymerization in the presence of In the aqueous pigment dispersant composed of the following, the weight ratio of the first monomer component and the second monomer component constituting the copolymer (B) is such that the first monomer component: second monomer component = 10: 90-50. : 50 relates to an aqueous pigment dispersant characterized by being 50.
[0009]
The present invention also provides a copolymer (B) obtained by polymerizing a second monomer component in a solvent in the presence of a solution of the copolymer (A) obtained by polymerizing the first monomer component in a solvent and MSD. ) After producing the solution, the copolymer (B) solution is desolvated to produce a copolymer (B) solid, and the copolymer (B) solid is Of alkali metal hydroxides and amines It is an object of the present invention to provide a method for producing an aqueous pigment dispersant, which is prepared by dissolving in alkaline water to produce an aqueous pigment dispersant.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The aqueous pigment dispersant according to the present invention is a copolymer obtained by polymerizing the second monomer component in the presence of the copolymer (A) obtained by polymerizing the first monomer component in the presence of MSD. (B).
[0011]
The first monomer component needs to contain 30% by weight or more of acrylic acid. When the content of acrylic acid is less than 30% by weight, the solubility of the copolymer (B) obtained below in alkaline water is remarkably lowered, so that it cannot be obtained in an aqueous solution or the pigment obtained The pigment dispersibility of the dispersant is extremely poor. As long as the effects of the present invention are not impaired, it is possible to use acid monomers other than acrylic acid, for example, methacrylic acid, maleic acid and maleic acid half esters, fumaric acid and fumaric acid half esters, itaconic acid and the like in combination. Can not be used in place of acrylic acid. When other acid monomer is used instead of acrylic acid, the polymerizability is lowered and copolymer (A) or copolymer (B) cannot be obtained, or copolymer (B) is alkalinized. The solubility in water is remarkably lowered and cannot be obtained in an aqueous solution, or the pigment dispersibility of the obtained pigment dispersant is remarkably inferior. In the present invention, it is not clear why 30% by weight or more of acrylic acid is essential in the first monomer component. However, in the case of monomers other than acrylic acid, the polymerizability in the presence of MSD decreases, and a copolymer ( Since a large amount of residual monomer remains in A), it is presumed that it may adversely affect the production of the copolymer (B) or the dissolution of the alkali.
[0012]
As the monomer constituting the first monomer component, monomers other than the above-mentioned monomers can be used as long as the effects of the present invention are not impaired. For example, styrene; α-methylstyrene; ethyl acrylate, butyl acrylate, acrylic Acrylic acid esters such as 2-ethylhexyl acid, benzyl acrylate, 2-hydroxyethyl acrylate, ethyl carbitol acrylate, methoxypolyethylene glycol acrylate, acryloylmorpholine; methacrylic acid and methyl methacrylate, butyl methacrylate, methacrylic acid Methacrylic acid esters such as benzyl, 2-hydroxyethyl methacrylate, methoxypolyethylene glycol methacrylate; acrylamide and derivatives thereof; methacrylamide and derivatives thereof; vinyl acetate; Rironitoriru; vinyl pyridine may be used.
[0013]
In the present invention, it is necessary to use 15 to 50% by weight of MSD with respect to the first monomer component. By polymerizing the first monomer component in the presence of MSD, a copolymer (A) having a reactive site derived from MSD at the terminal can be obtained. When the content of MSD is less than 15% by weight, the number of reactive sites derived from MSD at the end of the copolymer (A) decreases, so that the copolymer obtained by polymerization with the second monomer component as described later. The polymer (B) is not preferable because it is similar to a blend polymer of a polymer composed of the first monomer component and a polymer composed of the second monomer component. Further, when the content of MSD exceeds 50% by weight, the molecular weight of the copolymer (A) becomes small, so that the copolymer (B) obtained by polymerization with the second monomer component is structurally In addition, it is similar to the random copolymer product in terms of physical properties and is not preferable.
[0014]
The copolymer (A) can be obtained by polymerizing the first monomer component with a polymerization initiator in a solvent and MSD. The solvent to be used is not particularly limited, but a solvent in which MSD and the first monomer component are soluble is preferable, and a solvent having a boiling point of 100 to 180 ° C. is more preferable. Specifically, for example, alcohols such as methanol, ethanol and i-propanol; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and diethyl ether; ethylene glycol monoalkyl ethers or acetates thereof; propylene glycol monoalkyl Ethers or acetates thereof; polar organic solvents such as diethylene glycol monoalkyl ethers and nonpolar solvents such as toluene and xylene can be used singly or as a mixture. It is more preferable to use a glycol monoalkyl ether solvent at 180 ° C. alone or in combination. The polymerization initiator used is not particularly limited. For example, 2,2′-azobis (isobutyronitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (4- Methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2′-azobis (isobutyrate), 4,4′-azobis (4-cyanovaleric acid) ) Azo polymerization initiators such as benzoyl peroxide, di-t-butyl peroxide, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxymaleic acid, t-butyl peroxyisopropyl Selected from organic peroxide polymerization initiators such as monocarbonate, t-hexylperoxybenzoate, and t-butylperoxybenzoate Mixtures of more species or two or are used as appropriate.
[0015]
The weight average molecular weight of the copolymer (A) is 300 to 10000, preferably 400 to 3000. When the weight average molecular weight is less than 300, the following copolymer (B) is not preferable because it is similar in structure and physical properties to a random copolymer product. On the other hand, when it exceeds 10,000, the reactivity with the second monomer component is deteriorated, and as a result, it is not preferable because it is similar to a blend polymer of a polymer composed of the first monomer component and a polymer composed of the second monomer component.
[0016]
The second monomer component is a monomer mixture having a configuration different from that of the first monomer component, and needs to contain 80% by weight or more of a hydrophobic monomer. When the content of the hydrophobic monomer is less than 80% by weight, the segment composed of the second monomer component becomes hydrophilic, and the property is similar to that of the segment composed of the first monomer component. This results in poor dispersibility.
[0017]
Examples of hydrophobic monomers used include styrene; α-methylstyrene; hydrophobic acrylates such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and benzyl acrylate; methyl methacrylate, butyl methacrylate, Hydrophobic methacrylate esters such as benzyl methacrylate; vinyl acetate; acrylonitrile and the like.
[0018]
Other than the above as the second monomer component, hydrophilic acrylic esters such as acrylic acid and 2-hydroxyethyl acrylate, ethyl carbitol acrylate, methoxypolyethylene glycol acrylate, acryloylmorpholine, etc. Methacrylic acid and hydrophilic methacrylic acid esters such as 2-hydroxyethyl methacrylate and methoxypolyethylene glycol methacrylate; maleic acid and maleic acid esters; fumaric acid and fumaric acid esters; acrylamide and derivatives thereof; methacrylamide and Derivatives thereof such as vinyl pyridine can be used.
[0019]
The copolymer (B) can be obtained by polymerizing the second monomer component with a polymerization initiator in the presence of the copolymer (A) in a solvent. The solvent to be used is not particularly limited, and it is preferable if the copolymer (A) and the second monomer component are soluble, and more preferably if the boiling point is 100 to 180 ° C. Specifically, the solvent can be selected from the solvents that can be used in the production of the copolymer (A), and may be the same as or different from the solvent used in the polymerization of the copolymer (A). The polymerization initiator to be used is not particularly limited and can be selected from the polymerization initiators that can be used for the production of the copolymer (A), and is the same as the polymerization initiator used for the polymerization of the copolymer (A). Can be different.
[0020]
The copolymer (B) is obtained in the form of a copolymer (B) solution as described above. In the present invention, in order to obtain an aqueous pigment dispersant containing no organic solvent, the copolymer (B) solution is removed to produce a copolymer (B) solid. The solvent removal method is carried out by purification, or heating, reduced pressure, or heating under reduced pressure. In addition, when heating at the time of solvent removal, since the weight average molecular weight of a copolymer (B) changes with temperature and time, it is necessary to adjust heating temperature and heating time suitably. Although the increase in molecular weight varies depending on the monomer constituting the copolymer (B), generally, when the heating temperature exceeds 200 ° C., the increase in molecular weight is remarkably unfavorable.
[0021]
The weight average molecular weight of the copolymer (B) is 1000 to 60000, preferably 3000 to 20000. When the weight average molecular weight is less than 1000, the solubility in alkaline water is not preferable because it is insufficient. It is not preferable because undissolved material remains or the dissolved material has high viscosity and poor handling.
[0022]
The resin acid value of the copolymer (B) is preferably 50 to 400 mgKOH / g, more preferably 100 to 320 mgKOH / g. If the resin acid value is less than 50 mg KOH / g, it is insoluble in alkali and is not preferred. If it exceeds 400 mg KOH / g, the hydrophilicity is too strong, causing poor adsorption and aggregation on the pigment hydrophobic part, and as a result, The dispersibility of the pigment is extremely poor.
[0023]
The aqueous pigment dispersant according to the present invention can be obtained by dissolving the copolymer (B) solid in alkaline water. The alkaline water to be used is not particularly limited, and examples thereof include alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, ammonia, monoethanolamine, diethanolamine, triethanolamine, dimethylethanolamine, triethylamine, morpholine, 2 -Amines such as amino 2-methyl 1-propanol can be used.
[0024]
The aqueous pigment dispersant of the present invention may be added with water-soluble organic solvents such as alcohols and ketones compatible with water, antifoaming agents, rust preventives, preservatives, etc., if necessary. it can.
[0025]
The aqueous pigment dispersant according to the present invention having the above-described configuration can stably disperse inorganic and organic pigments, and when used in an ink or a coating agent, a printed matter having excellent printability and appearance. Can be suitably used in the fields of aqueous printing inks, paints, inkjet inks, coating agents, adhesives, films and the like.
[0026]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. In addition, the numerical value shown below is a basis of weight unless there is particular notice.
[0027]
[Example 1]
<Method for producing copolymer (A)>
A four-necked flask equipped with a stirrer, thermometer, nitrogen inlet tube, and reflux condenser was charged with 100 parts of ethylene glycol monomethyl ether (EM), heated in an oil bath with nitrogen replacement, and refluxed at an internal temperature of 120 ° C or higher. 30 parts of acrylic acid as the first monomer component, 6 parts of MSD, and dimethyl 2,2′-azobis (isobutyrate) with an acrylic acid ratio of 2 wt% (azo polymerization initiator, Wako Pure Chemical Industries, Ltd.) The product, product name: V-601) was added dropwise over 3 hours. After completion of dropping, the mixture was kept warm for 3 hours and cooled to room temperature to obtain a copolymer (A) solution having a solid content of 26.5%, A1. The weight average molecular weight (Mw) of A1 was about 870.
[0028]
<Method for producing copolymer (B)>
After obtaining A1 by the production method of copolymer (A), add 300 parts of EM to the above four-necked flask with A1 added, and heat in an oil bath while purging with nitrogen, and the internal temperature is 120 ° C or higher. And then styrene 64 parts of the second monomer component and t-butyl peroxybenzoate having a styrene ratio of 7 wt% (organic peroxide polymerization initiator, manufactured by NOF Corporation, trade name: perbutyl) A mixture of Z) was added dropwise over 3 hours. After completion of the dropwise addition, the solution was kept for 3 hours to obtain a copolymer (B) solution, and then distilled at atmospheric pressure while raising the internal temperature to 170 ° C. The solvent was removed to obtain B1 as a solid of the copolymer (B). B1 had Mw = 12000 and a resin acid value of 184.1 mgKOH / g.
[0029]
<Method for producing pigment dispersant>
B1 was dissolved in an aqueous ammonia having an equivalent resin acid value, and a pigment dispersant S1 that was a milky white varnish was obtained in an aqueous solution having a solid content of 17 wt%. S1 had a viscosity of 20 mPa · s / 25 ° C. and a pH of 8.8. There was no precipitate / insoluble matter.
[0030]
[Example 2]
The same operation as in Example 1 was carried out except that the raw materials used and the amounts used were changed as shown in Table 1, A2 as a copolymer (A) solution, B2 as a copolymer (B) solid, and S2 which is a pigment dispersant was obtained. A2 is Mw = 870, B2 is Mw = 9800, resin acid value is 186.4 mgKOH / g, S2 is a transparent varnish with a viscosity of 18 mPa · s / 25 ° C., pH = 8.5, and precipitate / insoluble There was nothing.
[0031]
[Example 3]
The same operation as in Example 1 was performed except that the raw materials used and the amounts used were changed as shown in Table 1, and A3 as a copolymer (A) solution, B3 as a copolymer (B) solid, and S3 which is a pigment dispersant was obtained. A3 is Mw = 1900, B3 is Mw = 5900, resin acid value is 67.5 mgKOH / g, S3 is a transparent varnish with a viscosity of 2.5 mPa · s / 25 ° C., pH = 9.2, and a precipitate・ There was no insoluble matter.
[0032]
[Example 4]
Except that the raw materials used and the amounts used were changed as shown in Table 1, the same operation as in the method for producing the copolymer (A) of Example 1 was carried out to obtain A4 as a copolymer (A) solution. In the method for producing the copolymer (B) of Example 1, the raw materials used were changed as shown in Table 1 to obtain a copolymer (B) solution, and then hexane was gradually added to the copolymer (B) solution. The precipitate thus obtained was filtered, air-dried at room temperature for one day, and heat-dried in a dry oven at 50 ° C. for 6 hours to obtain B4 as a copolymer (B) solid. Furthermore, the same operation as in the method for producing the pigment dispersant of Example 1 was performed to obtain S4 as a pigment dispersant from B4. A4 is Mw = 1800, B4 is Mw = 10000, resin acid value is 67.5 mgKOH / g, S4 is viscosity 35 mPa · s / 25 ° C., pH = 8.7, appearance translucent varnish, precipitate, There was no insoluble matter.
[0033]
[Comparative Example 1]
In Example 1, the same operation as in Example 1 was performed except that the copolymer (B) was produced using the raw materials shown in Table 1 in the absence of the copolymer (A). RB1, which is a combined (B) solid, and RS1, which is a comparative pigment dispersant, were obtained. RB1 was Mw = 8200, acid value 186.7 mgKOH / g, RS1 was a transparent varnish with a viscosity of 7.5 mPa · s / 25 ° C. and pH = 8.6, and there was no precipitate or insoluble matter.
[0034]
[Comparative Example 2]
Except that the raw materials used and the amounts used were changed as shown in Table 1, the same operation as in Example 1 was performed to obtain RA2 as a comparative copolymer (A) and RB2 as a comparative copolymer (B). . However, when RB2 was made into an aqueous solution having a solid content of 17% with ammonia water having an equivalent resin acid value, it did not dissolve and almost all precipitated. RA2 was Mw = 950, RB2 was Mw = 8500, and the resin acid value was 185.9 mgKOH / g.
[0035]
[Comparative Example 3]
Except that the raw materials used and the amounts used were changed as shown in Table 1, the same operations as in Example 1 were performed, RA3 being a comparative copolymer (A), RB3 being a comparative copolymer (B), and A comparative pigment dispersant RS3 was obtained. RA3 is Mw = 680, RB3 is Mw = 5100, resin acid value 163.8 mgKOH / g, RS3 is a viscosity of 3.0 mPa · s / 25 ° C., pH = 9.4, appearance translucent varnish, precipitated There was no thing, insoluble matter.
[0036]
[Comparative Example 4]
Except that the raw materials used and the amounts used were changed as shown in Table 1, the same operation as in Example 1 was performed to obtain RA4 as a comparative copolymer (A) and RB4 as a comparative copolymer (B). . However, when RB4 was made into an aqueous solution having a solid content of 17% with ammonia water having an equivalent resin acid value, it did not dissolve and almost all precipitated. RA4 was Mw = 2800, RB4 was Mw = 5900, and the resin acid value was 32.8 mgKOH / g.
[0037]
[Comparative Example 5]
Except that the raw materials used and the amounts used were changed as shown in Table 1, the same operation as in Example 1 was performed to obtain RA5 as a comparative copolymer (A) and RB5 as a comparative copolymer (B). . However, when RB5 was made into an aqueous solution having a solid content of 17% with ammonia water having an equivalent resin acid value, it did not dissolve and almost all precipitated. RA5 was Mw = 860, RB2 was Mw = 7900, and the resin acid value was 60.5 mgKOH / g.
[0038]
[Comparative Example 6]
Except that the raw materials used and the amounts used were changed as shown in Table 1, the same operations as in Example 1 were performed, RA6 being a comparative copolymer (A), RB6 being a comparative copolymer (B), and A comparative pigment dispersant RS6 was obtained. RA6 is Mw = 850, RB6 is Mw = 7500, resin acid value is 293.7 mgKOH / g, RS6 is viscosity 17.5 mPa · s / 25 ° C., pH = 9.0, appearance is a transparent varnish, precipitate There was no insoluble matter.
[0039]
[Comparative Example 7]
Except that the raw materials used and the amounts used were changed as shown in Table 1, the same operation as in Example 1 was performed, and RA7 as the comparative copolymer (A), RB7 as the comparative copolymer (B), and A comparative pigment dispersant RS7 was obtained. RA7 has Mw = 880, RB7 has Mw = 9200, resin acid value 192.4 mgKOH / g, RS7 has a viscosity of 9.0 mPa · s / 25 ° C., pH = 9.2, a transparent appearance varnish, precipitate There was no insoluble matter.
[0040]
[Comparative Example 8]
Except that the raw materials used were changed as shown in Table 1, the same operation as in Example 1 was performed, and RA8 as the comparative copolymer (A), RB8 as the comparative copolymer (B), and comparative pigment dispersion RS8 which is an agent was obtained. RA8 is Mw = 4000, RB3 is Mw = 4600, resin acid value is 157.7 mgKOH / g, RS8 is viscosity 23.5 mPa · s / 25 ° C., pH = 9.2, appearance milky varnish, precipitate There was no insoluble matter.
[0041]
[Comparative Example 9]
Except that the raw materials used and the amounts used were changed as shown in Table 1, the same operation as in Example 1 was performed to obtain RA9 as a comparative copolymer (A) and RB9 as a comparative copolymer (B). . However, when RB9 was made into an aqueous solution having a solid content of 17% with ammonia water having an equivalent resin acid value, it did not dissolve and almost all precipitated. RA9 was Mw = 1000, RB3 was Mw = 4700, and the resin acid value was 134.2 mgKOH / g.
[0042]
[Table 1]

[0043]
<Evaluation method of pigment dispersant>
In Comparative Examples 1, 3, 6, 7, and 8 except for Comparative Examples 2, 4, 5, and 9 in which the pigment dispersants S1 to S4 and the copolymer (B) obtained as described above could not be dissolved. Each pigment dispersant of comparative pigment dispersants RS1, RS3, RS6, RS7, and RS8 was evaluated as follows.
[0044]
1. Evaluation with titanium oxide dispersed ink
(1) Preparation of test ink
Each pigment dispersant having a 17% solid content concentration of 115.2 g (solid content of 19.6 g) and letdown emulsion J-140A (product name, manufactured by Seiko Chemical Industry Co., Ltd.) of 65.2 g (solid content of 26.1 g) ), 19.6 g of titanium oxide (Ishihara Sangyo Co., Ltd., trade name: TIPAQUE CR-90) (total solid ratio [wt%], resin varnish: J-140A: titanium oxide = 30: 40: 30), After mixing 300 g of glass beads and 1 g of a silicone-based antifoaming agent, shaking for 30 minutes with a paint shaker, the supernatant was collected, and test inks I1 to I4 and comparative test inks RI1, RI3, RI6, RI7, RI8 was created. Table 2 shows solid contents and viscosities of I1 to I4 and RI1, RI3, RI6, RI7, and RI8.
[0045]
[Table 2]

[0046]
(2) Evaluation of pigment dispersion stability of test ink
-Dispersion stability test: The same amount of each test ink was taken in separate glass bottles, and the degree of separation / sedimentation immediately after the dispersion ink was allowed to stand was visually evaluated according to the following criteria. The results are shown in Table 3.
A: Very stable without separation / sedimentation after 2 months
○: Separation / sedimentation is observed by 2 months, but stable for 1 month or more,
Δ: Separation / sedimentation is observed by 1 month, but stable for 2 weeks or more,
X: Separation / sedimentation is observed immediately after dispersion within 2 weeks.
[0047]
(3) Film color evaluation of test ink
Each test ink is No. The sample was developed on a PET film using a bar coater No. 8, and the gloss, concealability, adhesion, appearance, etc. were compared and confirmed. The results are shown in Table 3.
Gloss: 60 ° gloss was measured with a gloss meter.
-Concealing property: The concealing property of the printed surface formed on the film was visually evaluated according to the following criteria.
○: No underlying film layer is seen
Δ: The film layer is slightly transparent.
X: It can see through to the back side of a film layer, or a repellency is seen, and it cannot apply | coat uniformly.
[0048]
-Adhesion: A peel test using a cellophane tape was performed, and the adhesion was visually evaluated according to the following criteria.
A: No peeling at all
○: Slightly peeled off
Δ: Peeling considerably,
X: Almost peeled.
Appearance: The finished appearance of the printed surface formed on the film was comprehensively investigated from gloss, color development, swimming, etc., and evaluated according to the following criteria.
○: Good, Δ: Bad, ×: Remarkably bad.
[0049]
[Table 3]

[0050]
2． Evaluation by mica (muscovite) dispersion
(1) Preparation of mica dispersion
Each sample having a solid content concentration of 17% has a solid ratio of 16%, mica (product name A-31: manufactured by Yamaguchi Mica Industry Co., Ltd.) 30%, petroleum resin (product name QME-60, manufactured by Toho Chemical Industry Co., Ltd.) 54% The mica dispersions having a solid content of 43% in the total composition, D1 to D4, and RD1, RD3, RD6, RD7, and RD8 were prepared. Table 4 shows the viscosities and pH values of the obtained D1 to D4 and RD1, RD3, RD6, RD7, and RD8.
[0051]
(2) Evaluation of dispersion stability of mica dispersion
・ Dispersion stability test: Take the same amount of each mica dispersion in separate glass bottles and let stand at room temperature. The dispersion stability was visually evaluated. The results are shown in Table 4.
○: Stable without separation or viscosity difference between upper and lower layers after 1 month
Δ: Separation and viscosity difference between upper and lower layers are observed by 1 month, but stable for 2 weeks or more.
X: Separation and viscosity difference between upper and lower layers are observed immediately after dispersion within 2 weeks.
[0052]
[Table 4]

[0053]
As is apparent from the above results, the pigment dispersant according to the present invention has the same or better results in dispersion stability, color developability, and pigment dispersibility, particularly by the composition defined in the present invention. It was found that stability and gloss were remarkably excellent.
[0054]
【The invention's effect】
The pigment dispersant of the present invention has no problem of odor, is not accompanied by complicated production, and is a completely aqueous, non-VOC, and structure-controlled aqueous solution of a copolymer that is not suitable in the prior art. Can be manufactured stably. According to the present invention, a pigment dispersant having remarkably improved pigment dispersion stability, gloss and color developability can be obtained.

Claims (2)

Presence of 15 to 50% by weight of 2,4-diphenyl-4-methyl-1-pentene (hereinafter referred to as “MSD”) in the first monomer component containing 30% by weight or more of acrylic acid. An aqueous solution comprising a copolymer (B) obtained by polymerizing a second monomer component containing 80% by weight or more of a hydrophobic monomer in the presence of the copolymer (A) obtained by polymerization under In the pigment dispersant, the weight ratio of the first monomer component and the second monomer component constituting the copolymer (B) is first monomer component: second monomer component = 10: 90 to 50:50. An aqueous pigment dispersant characterized by The aqueous pigment dispersant according to claim 1, wherein the second monomer component is polymerized in a solvent in the presence of a solvent and a copolymer (A) solution obtained by polymerizing the first monomer component in MSD. After producing the copolymer (B) solution, the copolymer (B) solution is desolvated to produce a copolymer (B) solid, and the copolymer (B) solid is converted to an alkali metal. A method for producing an aqueous pigment dispersant, which comprises dissolving an aqueous hydroxide or amine in alkaline water to produce an aqueous pigment dispersant.