JP4736320B2 - Aqueous pigment dispersion for water-based ink for ink-jet recording and water-based ink for ink-jet recording - Google Patents
Aqueous pigment dispersion for water-based ink for ink-jet recording and water-based ink for ink-jet recording Download PDFInfo
- Publication number
- JP4736320B2 JP4736320B2 JP2003429200A JP2003429200A JP4736320B2 JP 4736320 B2 JP4736320 B2 JP 4736320B2 JP 2003429200 A JP2003429200 A JP 2003429200A JP 2003429200 A JP2003429200 A JP 2003429200A JP 4736320 B2 JP4736320 B2 JP 4736320B2
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- JP
- Japan
- Prior art keywords
- styrene
- meth
- monomer
- copolymer
- ink
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000006185 dispersion Substances 0.000 title claims description 180
- 239000000049 pigment Substances 0.000 title claims description 131
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims description 61
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical group C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 claims description 138
- 239000000178 monomer Substances 0.000 claims description 122
- 229920001577 copolymer Polymers 0.000 claims description 107
- 239000000976 ink Substances 0.000 claims description 94
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 claims description 82
- 125000001797 benzyl group Chemical group [H]C1=C([H])C([H])=C(C([H])=C1[H])C([H])([H])* 0.000 claims description 56
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 claims description 40
- 229920001909 styrene-acrylic polymer Polymers 0.000 claims description 38
- 239000002253 acid Substances 0.000 claims description 32
- 239000000126 substance Substances 0.000 claims description 32
- 229920002635 polyurethane Polymers 0.000 claims description 19
- 239000004814 polyurethane Substances 0.000 claims description 19
- 229920000642 polymer Polymers 0.000 claims description 17
- AOJOEFVRHOZDFN-UHFFFAOYSA-N benzyl 2-methylprop-2-enoate Chemical group CC(=C)C(=O)OCC1=CC=CC=C1 AOJOEFVRHOZDFN-UHFFFAOYSA-N 0.000 claims description 16
- 230000000379 polymerizing effect Effects 0.000 claims description 7
- 125000003011 styrenyl group Chemical group [H]\C(*)=C(/[H])C1=C([H])C([H])=C([H])C([H])=C1[H] 0.000 claims description 3
- 239000002245 particle Substances 0.000 description 55
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- 238000003786 synthesis reaction Methods 0.000 description 26
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- 238000000034 method Methods 0.000 description 17
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- 239000011521 glass Substances 0.000 description 15
- 239000000203 mixture Substances 0.000 description 15
- SOGAXMICEFXMKE-UHFFFAOYSA-N Butylmethacrylate Chemical compound CCCCOC(=O)C(C)=C SOGAXMICEFXMKE-UHFFFAOYSA-N 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 13
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- 239000000243 solution Substances 0.000 description 13
- 239000012736 aqueous medium Substances 0.000 description 12
- 239000003960 organic solvent Substances 0.000 description 12
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 11
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- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 9
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- 239000011259 mixed solution Substances 0.000 description 9
- 239000007787 solid Substances 0.000 description 9
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 8
- 238000001914 filtration Methods 0.000 description 8
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 8
- 230000003993 interaction Effects 0.000 description 8
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 6
- 125000004432 carbon atom Chemical group C* 0.000 description 6
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 description 6
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- HMZGPNHSPWNGEP-UHFFFAOYSA-N octadecyl 2-methylprop-2-enoate Chemical compound CCCCCCCCCCCCCCCCCCOC(=O)C(C)=C HMZGPNHSPWNGEP-UHFFFAOYSA-N 0.000 description 5
- 239000012860 organic pigment Substances 0.000 description 5
- 150000003839 salts Chemical class 0.000 description 5
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- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 3
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 3
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- MYRTYDVEIRVNKP-UHFFFAOYSA-N 1,2-Divinylbenzene Chemical compound C=CC1=CC=CC=C1C=C MYRTYDVEIRVNKP-UHFFFAOYSA-N 0.000 description 2
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- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 2
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- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
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- NRCMAYZCPIVABH-UHFFFAOYSA-N Quinacridone Chemical compound N1C2=CC=CC=C2C(=O)C2=C1C=C1C(=O)C3=CC=CC=C3NC1=C2 NRCMAYZCPIVABH-UHFFFAOYSA-N 0.000 description 2
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Landscapes
- Pigments, Carbon Blacks, Or Wood Stains (AREA)
- Inks, Pencil-Leads, Or Crayons (AREA)
- Ink Jet (AREA)
- Ink Jet Recording Methods And Recording Media Thereof (AREA)
Description
本発明は、インクジェット記録用水性インクのための水性顔料分散体及びインクジェット記録用水性インクに関する。 The present invention relates to an aqueous pigment dispersion for an inkjet recording aqueous ink and an inkjet recording aqueous ink.
顔料を水性媒体に分散させるためのスチレン系共重合体やアクリル系共重合体については、例えば、共重合体を構成する単量体組成、グラフト構造やブロック構造の様な立体構造、マイクロカプセルの様な多層化構造等について盛んに研究されている。インクジェット記録用水性インクの様な水性顔料記録液を調製する際に用いられる水性顔料分散体は、特に盛んに研究されている。 For styrene copolymers and acrylic copolymers for dispersing pigments in an aqueous medium, for example, the monomer composition constituting the copolymer, three-dimensional structure such as graft structure and block structure, microcapsule There have been many studies on such multilayered structures. Aqueous pigment dispersions used in preparing aqueous pigment recording liquids such as water-based inks for ink jet recording are particularly actively studied.
従来から、この分野では、インクジェットノズルのオリフィス面に対するインク濡れ性（ヘッドからのインクの吐出持続性）等を向上させる手段として、顔料の分散剤に、例えば、スチレン、α−メチルスチレン等のスチレン系単量体、或いはフェニル（メタ）アクリレート等の（メタ）アクリル酸フェニル系単量体、ベンジル（メタ）アクリレート、フェニルエチル（メタ）アクリレート、フェニルプロピル（メタ）アクリレート等の（メタ）アクリル酸フェニルアルキル系単量体等の様な、分子の末端にベンゼン環を有するモノエチレン性不飽和単量体を必須成分として重合せしめた重合体を用いることが積極的に提案されている。 Conventionally, in this field, as means for improving ink wettability (sustainability of ink ejection from the head) to the orifice surface of an ink jet nozzle, a pigment dispersant, for example, styrene such as styrene or α-methylstyrene is used. Monomers, or (meth) acrylic acid such as phenyl (meth) acrylate phenyl monomer, benzyl (meth) acrylate, phenylethyl (meth) acrylate, phenylpropyl (meth) acrylate, etc. It has been actively proposed to use a polymer obtained by polymerizing a monoethylenically unsaturated monomer having a benzene ring at the end of a molecule as an essential component, such as a phenylalkyl monomer.
この様なインクジェット記録用水性インクの調製に用いる重合体としては、具体的には、例えば、ベンジル（メタ）アクリレートやフェニルエチル（メタ）アクリレートの様な（メタ）アクリル酸フェニルアルキル系単量体と（メタ）アクリル酸とを共重合せしめたアクリル系共重合体が知られている（特許文献１参照）。この特許文献１には、具体的に、スチレン系単量体を含ませず、（メタ）アクリル酸フェニルアルキル系単量体が、４０モル％弱となる様にして重合したアクリル系共重合体が記載されている。 Specific examples of the polymer used for the preparation of such an aqueous ink for ink jet recording include, for example, (meth) acrylic acid phenylalkyl monomers such as benzyl (meth) acrylate and phenylethyl (meth) acrylate. There is known an acrylic copolymer obtained by copolymerizing (meth) acrylic acid (see Patent Document 1). Specifically, this Patent Document 1 does not contain a styrene monomer, and an acrylic copolymer obtained by polymerizing a phenylalkyl (meth) acrylate monomer to be less than 40 mol%. Is described.
しかしながら特許文献１に記載されている様なアクリル系共重合体を用いてインクジェット記録用水性インクを調製したのでは、被記録媒体上における優れた着色画像濃度は得られない。 However, when an aqueous ink for inkjet recording is prepared using an acrylic copolymer as described in Patent Document 1, an excellent color image density on a recording medium cannot be obtained.
また前記特許文献１とは別に、インクジェット記録用水性インクの調製に用いる重合体として、例えば、炭素原子数１４〜２０のアルキル基を有するモノアルコールと（メタ）アクリル酸とのエステルと（メタ）アクリル酸ベンジル系単量体とを必須成分として、必要に応じてスチレン系単量体及び／又は（メタ）アクリル酸フェニル系単量体とを共重合せしめて得たアクリル系共重合体が知られている（特許文献２）。この特許文献２は、優れた着色画像濃度を示すインクジェット記録用水性インクの提供を目的とするものであり、スチレン系単量体を必要に応じて用いる単量体としており、そこには、全単量体に対するスチレン系単量体及び（メタ）アクリル酸ベンジル系単量体の合計の含有割合は、１５重量％以上、好ましくは３０〜７０重量％のアクリル系共重合体が好適であることが記載されている。 In addition to Patent Document 1, examples of the polymer used for the preparation of the water-based ink for inkjet recording include, for example, an ester of a monoalcohol having an alkyl group having 14 to 20 carbon atoms and (meth) acrylic acid, and (meth) Acrylic copolymers obtained by copolymerizing benzyl acrylate monomers as essential components and copolymerizing styrene monomers and / or phenyl (meth) acrylate monomers as necessary are known. (Patent Document 2). This patent document 2 is intended to provide an aqueous ink for ink-jet recording exhibiting an excellent color image density, and uses a styrene-based monomer as necessary. The total content of the styrene monomer and the benzyl (meth) acrylate monomer relative to the monomer is preferably 15% by weight or more, preferably 30 to 70% by weight of the acrylic copolymer. Is described.
この特許文献２には、より具体的に、例えば、スチレン／ベンジルメタクリレート／メタクリル酸／ステアリルメタクリレート＝２２／４３／２７／９（モル％）となる様に共重合せしめた四元共重合体等の様なスチレン−アクリル共重合体を含むインクジェット記録用水性インクが記載されている。この特許文献２には、スチレン系単量体が３３モル％前後で、（メタ）アクリル酸ベンジル系単量体が６７モル％前後となる様にして重合したアクリル系共重合体が記載されている。 More specifically, in Patent Document 2, for example, a quaternary copolymer copolymerized so that styrene / benzyl methacrylate / methacrylic acid / stearyl methacrylate = 22/43/27/9 (mol%), etc. A water-based ink for ink-jet recording containing such a styrene-acrylic copolymer is described. This Patent Document 2 describes an acrylic copolymer that is polymerized so that the styrene monomer is about 33 mol% and the benzyl (meth) acrylate monomer is about 67 mol%. Yes.
しかしながら、特許文献２に記載されている様なスチレン−アクリル系共重合体を用いてインクジェット記録用水性インクを調製したのでは、やはり、被記録媒体上における優れた着色画像濃度は得られない。 However, when a water-based ink for inkjet recording is prepared using a styrene-acrylic copolymer as described in Patent Document 2, an excellent colored image density on a recording medium cannot be obtained.
即ち従来の技術は、いずれも、スチレン系単量体や（メタ）アクリル酸ベンジル系単量体の重合体からもたらされる技術的効果を同一視したものばかりであり、依然、スチレン−アクリル系共重合体のモノマー構成と性質との関係は充分に知られていない。スチレン−アクリル系共重合体が、これら各単量体の両方をどの様な含有割合で含有させ重合体とした場合に、どの様な特異的性質が発現するかについては、未だ詳しく検討されていないのが実状である。 In other words, all of the conventional techniques equate the technical effects brought about by the polymers of styrene monomers and benzyl (meth) acrylate monomers. The relationship between the monomer composition and properties of the polymer is not well known. The specific properties of the styrene-acrylic copolymer when it is made into a polymer by containing both of these monomers in various proportions have not yet been studied in detail. There is no actual situation.
つまり、特許文献１及び２の様な共重合体を用いた場合には、依然として、被記録媒体上の高い着色画像濃度を有するインクジェット記録用水性インクを調製することが出来ないという欠点があった。 That is, when the copolymers as in Patent Documents 1 and 2 are used, there is still a drawback that it is impossible to prepare an aqueous ink for inkjet recording having a high colored image density on the recording medium. .
本発明は、被記録媒体上の高い着色画像濃度を有するインクジェット記録用水性インクのための水性顔料分散体及びインクジェット記録用水性インクを得ることを課題とする。 An object of the present invention is to obtain an aqueous pigment dispersion for an inkjet recording aqueous ink having a high color image density on a recording medium and an inkjet recording aqueous ink.
本発明者等は、共重合体の分子量や酸価を固定して、スチレン系単量体と（メタ）アクリル酸ベンジル系単量体とを種種の含有割合となる様に振って各種のスチレン−アクリル系共重合体を製造し、これらから各々水性顔料分散体並びにインクジェット記録用水性インクを調製し、被記録媒体上の着色画像濃度について測定を行った。 The inventors fixed the molecular weight and acid value of the copolymer, and changed the styrene monomer and the benzyl (meth) acrylate monomer to various content ratios. -Acrylic copolymers were produced, aqueous pigment dispersions and water-based inks for inkjet recording were prepared from these, and the color image density on the recording medium was measured.
その結果、インクジェット記録用水性インクの調製に用いるスチレン−アクリル系共重合体としては、（メタ）アクリル酸ベンジル系単量体の重合単位を含み、スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計の含有割合が一定の範囲にあるというだけでなく、それら合計に占めるスチレン系単量体の含有割合も限られた一定範囲であるスチレン−アクリル系共重合体が、被記録媒体上の高い着色画像濃度を有するインクジェット記録用水性インクのための水性顔料分散体となることを見い出し、本発明を完成するに至った。 As a result, the styrene-acrylic copolymer used for the preparation of the water-based ink for ink jet recording includes a polymer unit of a benzyl (meth) acrylate monomer, and includes a styrene monomer and benzyl (meth) acrylate. Not only that the total content ratio with the system monomer is in a certain range, but also the styrene-acrylic copolymer in which the content ratio of the styrene monomer in the total is a limited range, It has been found that it is an aqueous pigment dispersion for an aqueous ink for inkjet recording having a high color image density on the recording medium, and the present invention has been completed.
即ち本発明は、顔料（Ａ）と、スチレン系単量体と（メタ）アクリル酸ベンジル系単量体と（メタ）アクリル酸とを重合せしめたスチレン−アクリル系共重合体（Ｂ）と、塩基性物質（Ｃ）とを含有するインクジェット記録用水性インクのための水性顔料分散体において、前記スチレン−アクリル系共重合体（Ｂ）として、（メタ）アクリル酸ベンジル系単量体の重合単位を含み、スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計が４０〜８０モル％であり、スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル数に対するスチレン系単量体のモル数が４０〜９０％であり、かつ、酸価８５〜１３５のスチレン−アクリル系共重合体を用いることを特徴とする水性顔料分散体を提供する。 That is, the present invention comprises a pigment (A), a styrene-acrylic copolymer (B) obtained by polymerizing a styrene monomer, a benzyl (meth) acrylate monomer, and (meth) acrylic acid, In the aqueous pigment dispersion for an inkjet recording aqueous ink containing a basic substance (C), a polymer unit of a benzyl (meth) acrylate monomer as the styrene-acrylic copolymer (B) The total of the styrene monomer and the benzyl (meth) acrylate monomer is 40 to 80 mol%, and the total of the styrene monomer and the benzyl (meth) acrylate monomer Provided is an aqueous pigment dispersion characterized by using a styrene-acrylic copolymer having a styrene monomer of 40 to 90% and an acid value of 85 to 135 with respect to the number of moles.
また、本発明は前記記載の水性顔料分散体を含有するインクジェット記録用水性インクを提供する。 The present invention also provides an aqueous ink for ink-jet recording containing the above-described aqueous pigment dispersion.
本発明の水性顔料分散体は、スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル数に対するスチレン系単量体のモル数が従来より多く４０〜９０％であるスチレン−アクリル系共重合体を含有しているので、インクジェット記録用水性インクを調製した際、被記録媒体上における高い着色画像濃度を得ることが出来るという格別顕著な効果を奏する。 The aqueous pigment dispersion of the present invention is a styrene in which the number of moles of styrene monomer relative to the total number of moles of styrene monomer and benzyl (meth) acrylate monomer is 40 to 90% more than before. -Since it contains an acrylic copolymer, when a water-based ink for ink jet recording is prepared, it has a particularly remarkable effect that a high colored image density on a recording medium can be obtained.
本発明において（メタ）アクリル酸とは、アクリル酸とメタクリル酸との両方を包含する技術用語である。同様に本発明におけるスチレン−アクリル系共重合体とは、スチレン系単量体と（メタ）アクリル酸ベンジル系単量体と（メタ）アクリル酸とを必須成分として重合した共重合体を意味する技術用語である。水性媒体とは、水のみ又は水と水溶性有機溶剤との混合物で質量換算で６０％以上の水を含有するものを言う。 In the present invention, (meth) acrylic acid is a technical term including both acrylic acid and methacrylic acid. Similarly, the styrene-acrylic copolymer in the present invention means a copolymer obtained by polymerizing styrene monomer, benzyl (meth) acrylate monomer and (meth) acrylic acid as essential components. It is a technical term. The aqueous medium means a mixture of water alone or a mixture of water and a water-soluble organic solvent and containing 60% or more of water in terms of mass.
本発明の水性顔料分散体とは、水性媒体中に、顔料（Ａ）と、スチレン系単量体と（メタ）アクリル酸ベンジル系単量体と（メタ）アクリル酸とを重合せしめた、スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計が４０〜８０モル％であり、スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル数に対するスチレン系単量体のモル数が４０〜９０％であり、かつ、酸価８５〜１３５のスチレン−アクリル系共重合体〔以下、共重合体（Ｂ）と略記する。〕と、塩基性物質（Ｃ）とを含有するものである。 The aqueous pigment dispersion of the present invention is a styrene obtained by polymerizing a pigment (A), a styrene monomer, a benzyl (meth) acrylate monomer, and (meth) acrylic acid in an aqueous medium. The total of the styrene monomer and the benzyl (meth) acrylate monomer is 40 to 80 mol%, and styrene with respect to the total number of moles of the styrene monomer and the benzyl (meth) acrylate monomer A styrene-acrylic copolymer having a mole number of the monomer based on 40 to 90% and an acid value of 85 to 135 [hereinafter abbreviated as copolymer (B). And a basic substance (C).
本発明の水性顔料分散体において、その水性媒体に分散している粒子（以下、分散粒子と言う。）は、顔料（Ａ）粒子と共重合体（Ｂ）粒子であっても良いが、顔料（Ａ）が共重合体（Ｂ）により被覆された複合粒子の形態であっても良い。そして水性顔料分散体には、前記分散粒子が、平均分散粒径（メディアン径）が５０〜２００ｎｍとなる様に分散している。 In the aqueous pigment dispersion of the present invention, the particles dispersed in the aqueous medium (hereinafter referred to as dispersed particles) may be pigment (A) particles and copolymer (B) particles. (A) may be in the form of composite particles coated with the copolymer (B). In the aqueous pigment dispersion, the dispersed particles are dispersed so that the average dispersed particle diameter (median diameter) is 50 to 200 nm.
本発明の水性顔料分散体の調製に用いる顔料（Ａ）は、有機顔料或いは無機顔料であり、公知慣用のものがいずれも使用出来る。 The pigment (A) used for the preparation of the aqueous pigment dispersion of the present invention is an organic pigment or an inorganic pigment, and any known one can be used.
本発明における共重合体（Ｂ）は、スチレン系単量体と、（メタ）アクリル酸ベンジル系単量体と、（メタ）アクリル酸と、必要に応じてその他の共重合可能なモノエチレン性不飽和単量体を共重合することにより容易に得ることが出来る。こうすることで、前記各単量体を重合単位として含有する共重合体（Ｂ）が得られる。 The copolymer (B) in the present invention comprises a styrene monomer, a benzyl (meth) acrylate monomer, (meth) acrylic acid, and other copolymerizable monoethylenic monomers as necessary. It can be easily obtained by copolymerizing an unsaturated monomer. By carrying out like this, the copolymer (B) which contains the said each monomer as a polymerization unit is obtained.
スチレン系単量体としては、例えば、スチレン、α−メチルスチレン、ｏ−メチルスチレン、ｍ−メチルスチレン、ｐ−メチルスチレン、ｐ−ｔ−ブチルスチレン、４−メトキシスチレン、４−クロロスチレン等が挙げられるが、中でもスチレン又はα−メチルスチレンが本発明の技術的効果への寄与がより優れる点、容易に入手でき安価である点で好ましい。 Examples of the styrene monomer include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, pt-butylstyrene, 4-methoxystyrene, 4-chlorostyrene, and the like. Among them, styrene or α-methylstyrene is preferable because it contributes more to the technical effect of the present invention and is easily available and inexpensive.
（メタ）アクリル酸ベンジル系単量体としては、例えば、アクリル酸ベンジル、メタクリル酸ベンジルが挙げられるが、中でもメタクリル酸ベンジルは本発明の技術的効果への寄与がより優れる点、容易に入手でき安価である点で好ましい。 Examples of the benzyl (meth) acrylate monomer include benzyl acrylate and benzyl methacrylate. Among them, benzyl methacrylate is easily available because it contributes more to the technical effect of the present invention. It is preferable in that it is inexpensive.
（メタ）アクリル酸としては、アクリル酸又はメタクリル酸が挙げられる。（メタ）アクリル酸は、電気的中性状態とアニオン状態の共存範囲を広く制御出来、入手のしやすさ、価格等の点で好ましい。 Examples of (meth) acrylic acid include acrylic acid and methacrylic acid. (Meth) acrylic acid is preferable in terms of availability, price, etc., because the coexistence range of the electrically neutral state and the anion state can be controlled widely.
本発明における共重合体（Ｂ）は、スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計が４０〜８０モル％、好適には７０〜８０モル％のスチレン−アクリル系共重合体である。 In the copolymer (B) in the present invention, the total of the styrene monomer and the benzyl (meth) acrylate monomer is 40 to 80 mol%, preferably 70 to 80 mol%. It is a copolymer.
また本発明における共重合体（Ｂ）は、スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル数に対するスチレン系単量体のモル数が４０〜９０％、好適には５０〜９０％のスチレン−アクリル系共重合体である。 In the copolymer (B) in the present invention, the number of moles of the styrene monomer relative to the total number of moles of the styrene monomer and the benzyl (meth) acrylate monomer is preferably 40 to 90%. Is a 50-90% styrene-acrylic copolymer.
本発明における共重合体（Ｂ）としては、スチレン系単量体がスチレン、かつ（メタ）アクリル酸ベンジル系単量体がメタクリル酸ベンジルであるスチレン−アクリル系共重合体であることが好ましく、なかでも、スチレンとメタクリル酸ベンジルとの合計モル数に対するスチレンのモル数が５０〜９０％のスチレン−アクリル系共重合体であることが最も好ましい。 The copolymer (B) in the present invention is preferably a styrene-acrylic copolymer in which the styrene monomer is styrene and the benzyl (meth) acrylate monomer is benzyl methacrylate, Among these, a styrene-acrylic copolymer having a styrene mole number of 50 to 90% with respect to the total mole number of styrene and benzyl methacrylate is most preferable.
スチレン系単量体の重合単位を含まず（メタ）アクリル酸ベンジル系単量体の重合単位を多く含有する共重合体は、着色画像の被記録媒体上への接着性を高めることを出来、単純接触による着色画像の表面擦過痕の発生防止には有効であるが、被記録媒体上の着色画像濃度を思った程は大きく改善することが出来ない。 A copolymer containing a large number of polymer units of benzyl (meth) acrylate monomers without containing polymer units of styrene monomers can enhance the adhesion of colored images onto the recording medium, Although effective in preventing the occurrence of surface scratches on the colored image due to simple contact, the color image density on the recording medium cannot be improved as much as expected.
一方、スチレン系単量体の重合単位を多く含有する共重合体は、着色画像のひび割れや、加重接触による着色画像自体の被記録媒体からの剥離が起こりやすいことから、通常、後記するその他の（メタ）アクリル酸エステル等と併用して用いられる。また、スチレン系単量体の重合単位を多く含有する共重合体は、プリンター等のインク吐出ノズル界面との相互作用により、吐出応答性が不充分となって、着色画像にかすれが生じたり、ノズル目詰まりを引き起こしたりすることがある。 On the other hand, a copolymer containing a large number of polymerized units of a styrenic monomer tends to cause cracks in the colored image and peeling of the colored image itself from the recording medium due to weighted contact. Used in combination with (meth) acrylic acid esters and the like. In addition, the copolymer containing a large number of styrene monomer polymerization units, due to the interaction with the ink discharge nozzle interface of the printer or the like, the discharge response is insufficient, the color image may be blurred, It may cause nozzle clogging.
共重合体（Ｂ）は、前記した含有割合の数値の範囲内で、単純接触及び加重接触どちらの場合においても問題がなく、被記録媒体上の着色画像濃度をより高めることが出来る。より具体的には、この範囲で被記録媒体として普通紙を対象とした場合に、高い着色画像濃度と良好な印字状態が兼備される。 The copolymer (B) has no problem in both cases of simple contact and weighted contact within the above range of the content ratio, and can further increase the color image density on the recording medium. More specifically, when a plain paper is used as a recording medium within this range, a high colored image density and a good printing state are combined.
共重合体（Ｂ）のスチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計の含有割合と、スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計に占めるスチレン系単量体の含有割合とを、各々前記した範囲することで、被記録媒体上における着色画像濃度を高めることが出来る。より具体的には、被記録媒体として普通紙を対象とした場合における着色画像濃度をより高められる点で好ましい。当業界においては、着色画像濃度が高いことを発色性に優れると言う場合もある。尚、被記録媒体上の着色画像は、着色樹脂皮膜からなるものである。 Total content of copolymer (B) styrene monomer and benzyl (meth) acrylate monomer, and sum of styrene monomer and benzyl (meth) acrylate monomer By setting the content ratio of the styrene monomer in the above-mentioned range, the color image density on the recording medium can be increased. More specifically, this is preferable in that the color image density can be further increased when plain paper is used as the recording medium. In this industry, a high colored image density may be said to be excellent in color developability. The colored image on the recording medium is made of a colored resin film.
また本発明における共重合体（Ｂ）は、（メタ）アクリル酸の重合単位を必須として含有するスチレン−アクリル系共重合体である。前記した通り、この重合単位は共重合体を水性媒体中へ分散させるために不可欠な重合単位であり、この重合単位により共重合体の水への親和性を高めることが出来、水性媒体への共重合体の分散性や水性顔料分散体とした際の分散粒子の分散安定性をより良好とすることが出来る。 The copolymer (B) in the present invention is a styrene-acrylic copolymer containing a polymerization unit of (meth) acrylic acid as an essential component. As described above, this polymerized unit is an indispensable polymer unit for dispersing the copolymer in the aqueous medium, and this polymerized unit can increase the affinity of the copolymer for water, The dispersibility of the copolymer and the dispersion stability of the dispersed particles when made into an aqueous pigment dispersion can be improved.
共重合体（Ｂ）におけるスチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル数、この合計モル数に対するスチレン系単量体のモル％、併用したその他の共重合可能なエチレン性不飽和単量体の種類や量及び共重合体の分子量等が一定の条件のもとでの対比では、共重合体（Ｂ）の酸価が小さすぎると分散粒子の分散安定性が低下する傾向にあり、逆に、共重合体（Ｂ）の酸価が大きすぎると着色画像の耐水性や着色画像濃度も低下する傾向があり、いずれも好ましくない。 Total number of moles of styrene monomer and benzyl (meth) acrylate monomer in copolymer (B), mole% of styrene monomer relative to the total mole number, and other copolymerizations that can be used together When the acid value of the copolymer (B) is too small, the dispersion stability of the dispersed particles can be reduced by comparing the type and amount of the ethylenically unsaturated monomer and the molecular weight of the copolymer under certain conditions. Conversely, if the acid value of the copolymer (B) is too large, the water resistance of the colored image and the color image density tend to decrease, both of which are not preferred.
この様な観点から共重合体（Ｂ）は、酸価が８５〜１３５ｍｇＫＯＨ／ｇ、なかでも酸価８５〜１１０ｍｇＫＯＨ／ｇの範囲で、被記録媒体として普通紙を対象とした場合に、特に高い着色画像濃度が得られる点で、特に好ましい。ここで酸価とは、共重合体１ｇを中和するために必要な水酸化カリウムのｍｇ数を意味する。共重合体（Ｂ）をこの様な酸価とするには、全重合単位中の（メタ）アクリル酸の重合単位の含有割合を、通常８〜２５％、好適には１０〜１８％となる様にする。尚、ここでの％は質量基準である。（メタ）アクリル酸は、モル基準では１５〜３０モル％とすれば良い。 From this point of view, the copolymer (B) has an acid value in the range of 85 to 135 mgKOH / g, particularly an acid value in the range of 85 to 110 mgKOH / g, and is particularly high when plain paper is used as a recording medium. This is particularly preferable in that a color image density can be obtained. Here, the acid value means the number of mg of potassium hydroxide necessary for neutralizing 1 g of the copolymer. In order to make the copolymer (B) have such an acid value, the content ratio of the polymerization units of (meth) acrylic acid in all the polymerization units is usually 8 to 25%, preferably 10 to 18%. Like. Here,% is based on mass. (Meth) acrylic acid may be 15 to 30 mol% on a molar basis.
本発明における共重合体（Ｂ）が前記酸価にあることが、後記塩基性物質（Ｃ）にて中和した共重合体の水性媒体への分散性が良好で、水性顔料分散体とした際の分散粒子の分散安定性への寄与が顕著である。より具体的には、この水性顔料分散体は、インクジェット記録用水性インクの調製に適用した場合に、分散粒子の分散安定性が良好となるので好ましい。 The copolymer (B) in the present invention has the above acid value, the copolymer neutralized with the basic substance (C) described later has good dispersibility in an aqueous medium, and an aqueous pigment dispersion is obtained. The contribution to the dispersion stability of the dispersed particles is remarkable. More specifically, this aqueous pigment dispersion is preferable because the dispersion stability of dispersed particles becomes good when applied to the preparation of an aqueous ink for inkjet recording.
共重合体（Ｂ）は、スチレン系単量体、（メタ）アクリル酸ベンジル系単量体、（メタ）アクイル酸とを共重合せしめた共重合体であれば良いが、更に、水酸基を有する（メタ）アクリル酸エステル系単量体を併用して共重合せしめた共重合体であっても良い。 The copolymer (B) may be a copolymer obtained by copolymerizing a styrene monomer, a benzyl (meth) acrylate monomer, and (meth) acrylic acid, and further has a hydroxyl group. A copolymer obtained by copolymerizing a (meth) acrylic acid ester monomer may be used.
水酸基を有する（メタ）アクリル酸エステル系単量体としては、例えば、（メタ）アクリル酸２−ヒドロキシエチル、（メタ）アクリル酸２−ヒドロキシプロピル、（メタ）アクリル酸３−ヒドロキシプロピル等のヒドロキシアルキル（メタ）アクリレート、ジエチレングリコールモノ（メタ）アクリレート、トリエチレングリコールモノ（メタ）アクリレート、ポリエチレングリコールモノ（メタ）アクリレート、プロピレングリコールモノ（メタ）アクリレート、ジプロピレングリコールモノ（メタ）アクリレート、トリプロピレングリコールモノ（メタ）アクリレート、テトラメチレンエーテルグルコールモノ（メタ）アクリレート、ポリエチレンオキシド−ポリプロピレンオキシドのランダムポリマーグリコール又は同ブロックポリマーグリコールのモノ（メタ）アクリレート、ポリエチレンオキシド−ポリテトラメチレンエーテルのランダムポリマーグリコール又は同ブロックポリマーグリコールのモノ（メタ）アクリレート等のアルキレングリコールモノ（メタ）アクリレートが挙げられるが、中でもヒドロキシアルキル（メタ）アクリレートは共重合体のガラス転移温度の調整や共重合体の低粘度化が容易であり、容易に入手でき安価である点で好ましい。以下、ガラス転移温度はＴｇと言う。 Examples of the (meth) acrylic acid ester monomer having a hydroxyl group include hydroxy such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 3-hydroxypropyl (meth) acrylate. Alkyl (meth) acrylate, diethylene glycol mono (meth) acrylate, triethylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, propylene glycol mono (meth) acrylate, dipropylene glycol mono (meth) acrylate, tripropylene glycol Mono (meth) acrylate, tetramethylene ether glycol mono (meth) acrylate, polyethylene oxide-polypropylene oxide random polymer glycol or the same block poly -Alkylene glycol mono (meth) acrylates such as mono (meth) acrylate of glycol, random polymer glycol of polyethylene oxide-polytetramethylene ether or mono (meth) acrylate of the block polymer glycol, among others, hydroxyalkyl (meth) Acrylates are preferred because they are easy to adjust the glass transition temperature of the copolymer and to reduce the viscosity of the copolymer, and are easily available and inexpensive. Hereinafter, the glass transition temperature is referred to as Tg.
共重合体（Ｂ）の全重合単位中の水酸基を有する（メタ）アクリル酸エステル系単量体の重合単位の含有割合は特に制限されないが、通常３〜２０％、好適には５〜１５％である。尚、ここでの％は質量基準である。水酸基を有する（メタ）アクリル酸エステル系単量体は、モル基準では３〜１５モル％とすれば良い。 Although the content rate of the polymerization unit of the (meth) acrylic acid ester-based monomer having a hydroxyl group in all the polymerization units of the copolymer (B) is not particularly limited, it is usually 3 to 20%, preferably 5 to 15%. It is. Here,% is based on mass. The (meth) acrylic acid ester monomer having a hydroxyl group may be 3 to 15 mol% on a molar basis.
本発明における共重合体（Ｂ）は、Ｔｇが、５〜９０℃の範囲にあることが、前記分散性や分散安定性が良好で、またインクジェット記録用水性インクの調製に使用した場合の印字安定性が良く、着色画像の耐水性も良好な上、耐摩擦性、耐棒積み性等の画像保存性も良好となるので好ましい。ここで、共重合体（Ｂ）のＴｇは、各単量体のホモポリマーのＴｇから算術的に求められる計算値である。 The copolymer (B) in the present invention has a Tg in the range of 5 to 90 ° C., has good dispersibility and dispersion stability, and printing when used for the preparation of water-based ink for ink jet recording. The stability is good, the water resistance of the colored image is good, and the image storability such as friction resistance and bar stacking resistance is also good, which is preferable. Here, Tg of a copolymer (B) is a calculated value calculated | required arithmetically from Tg of the homopolymer of each monomer.
本発明における共重合体（Ｂ）は、スチレン系単量体、（メタ）アクリル酸ベンジル系単量体及び（メタ）アクリル酸を必須成分として、前二者の重合単位が前記した含有割合となる様にしかつ最後者が特定酸価となる含有割合となる様に、共重合せしめたスチレン−アクリル共重合体であるが、必要に応じて、例えば、前記したＴｇや酸価等の調整のために、前記水酸基を有する（メタ）アクリル酸エステル系単量体やこれらと共重合し得るその他のエチレン性不飽和単量体を更に併用することで、前記した単量体の重合単位とは異なる重合単位を含有する共重合体（Ｂ）とすることが出来る。この様な共重合体（Ｂ）も本発明の水性顔料分散体の調製に使用することが出来る。 The copolymer (B) in the present invention contains the styrene monomer, the benzyl (meth) acrylate monomer, and the (meth) acrylic acid as essential components, and the content ratios of the former two polymer units are as described above. The styrene-acrylic copolymer is copolymerized so that the content of the latter becomes a specific acid value, but if necessary, for example, adjustment of Tg, acid value, etc. Therefore, by further using together with the (meth) acrylic acid ester monomer having a hydroxyl group and other ethylenically unsaturated monomers that can be copolymerized therewith, the polymerization unit of the monomer described above is It can be set as the copolymer (B) containing a different polymerization unit. Such a copolymer (B) can also be used for the preparation of the aqueous pigment dispersion of the present invention.
前記した単量体と共重合し得るその他のエチレン性不飽和単量体としては、例えば、（メタ）アクリル酸メチル、（メタ）アクリル酸ｎ−ブチル、（メタ）アクリル酸２−エチルヘキシル、（メタ）アクリル酸ｎ−オクチル、（メタ）アクリル酸ドデシル、（メタ）アクリル酸オクタデシル、（メタ）アクリル酸シクロヘキシル、（メタ）アクリル酸イソボルニル、マレイン酸ジメチル、フマル酸ジメチル、（メタ）アクリル酸２−アミノエチル等の不飽和脂肪酸エステル類；（メタ）アクリルアミド、Ｎ−メチル（メタ）アクリルアミド等の不飽和脂肪酸アミド類；（メタ）アクリロニトリル等の不飽和ニトリル類；酢酸ビニル、プロピオン酸ビニル等の不飽和エーテル類；エチレン、プロピレン、１−ブテン、１−オクテン、ビニルシクロヘキサン、４−ビニルシクロヘキセン、等の不飽和炭化水素類；塩化ビニル、塩化ビニリデン、テトラフルオロエチレン、３−クロロプロピレン、等の不飽和ハロゲン化炭化水素類；４−ビニルピリジン、Ｎ−ビニルカルバゾール、Ｎ−ビニルピロリドン、等のビニル置換複素環化合物類；前記例示単量体中のカルボキシル基、水酸基、アミノ基等の活性水素を含有する置換基を含有する単量体とエチレンオキシド、プロピレンオキシド、シクロヘキセンオキシド等、エポキシド類との反応生成物；前記例示単量体中の水酸基、アミノ基等を含有する置換基を含有する単量体と酢酸、プロピオン酸、ブタン酸、ヘキサン酸、デカン酸、ドデカン酸等のカルボン酸類との反応生成物等を挙げることが出来る。 Examples of other ethylenically unsaturated monomers that can be copolymerized with the above monomers include, for example, methyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( N-octyl (meth) acrylate, dodecyl (meth) acrylate, octadecyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dimethyl maleate, dimethyl fumarate, (meth) acrylic acid 2 -Unsaturated fatty acid esters such as aminoethyl; unsaturated fatty acid amides such as (meth) acrylamide and N-methyl (meth) acrylamide; unsaturated nitriles such as (meth) acrylonitrile; vinyl acetate, vinyl propionate, etc. Unsaturated ethers; ethylene, propylene, 1-butene, 1-octene, vinyl Unsaturated hydrocarbons such as hexane and 4-vinylcyclohexene; Unsaturated halogenated hydrocarbons such as vinyl chloride, vinylidene chloride, tetrafluoroethylene and 3-chloropropylene; 4-vinylpyridine, N-vinylcarbazole, Vinyl-substituted heterocyclic compounds such as N-vinylpyrrolidone; monomers containing a substituent containing an active hydrogen such as a carboxyl group, a hydroxyl group, and an amino group, and ethylene oxide, propylene oxide, and cyclohexene in the above exemplary monomers; Reaction products with epoxides such as oxides; Monomers containing substituents containing hydroxyl groups, amino groups, etc. in the above exemplified monomers and acetic acid, propionic acid, butanoic acid, hexanoic acid, decanoic acid, dodecane Examples include reaction products with carboxylic acids such as acids.
本発明における共重合体（Ｂ）としては、前記した４種の各単量体の各重合単位の他に、炭素原子数１４未満のアルキル基を有する（メタ）アクリル酸アルキルエステル系単量体を共重合せしめた共重合体が好ましい。 As the copolymer (B) in the present invention, a (meth) acrylic acid alkyl ester monomer having an alkyl group having less than 14 carbon atoms in addition to the respective polymerized units of the aforementioned four types of monomers. A copolymer obtained by copolymerizing is preferred.
前記炭素原子数１４未満のアルキル基を含有する（メタ）アクリル酸アルキルエステル系単量体を共重合せしめた共重合体（Ｂ）は、炭素原子数１４以上のアルキル基を含有する（メタ）アクリル酸アルキルエステル系単量体を共重合せしめた同様の共重合体（Ｂ）に比べて、Ｔｇを高く設計することができ、着色画像皮膜の剛性をより高めることが出来、単純接触による着色画像の表面擦過痕の発生防止には有効である点で好ましい。 The copolymer (B) obtained by copolymerizing the (meth) acrylic acid alkyl ester monomer containing an alkyl group having less than 14 carbon atoms contains an alkyl group having 14 or more carbon atoms (meth). Compared to the same copolymer (B) obtained by copolymerizing an alkyl acrylate monomer, the Tg can be designed higher, the rigidity of the colored image film can be further increased, and coloring by simple contact This is preferable in that it is effective in preventing the occurrence of scratches on the surface of the image.
本発明における共重合体（Ｂ）の重量平均分子量は、特に制限されるものではないが、水性顔料分散体の粘度が低く、分散安定性も良好で、インクジェット記録用水性インクの調製に使用した場合に長期間安定した印字を行わせることが容易な点で、５，０００〜１００，０００の範囲とすることが好ましく、１０，０００〜７０，０００の範囲とすることが特に好ましい。 The weight average molecular weight of the copolymer (B) in the present invention is not particularly limited, but the aqueous pigment dispersion has a low viscosity and good dispersion stability, and was used for the preparation of an aqueous ink for inkjet recording. In this case, the range of 5,000 to 100,000 is preferable, and the range of 10,000 to 70,000 is particularly preferable because it is easy to perform stable printing for a long time.
本発明における共重合体（Ｂ）は、前記各単量体を前記各重合単位の含有割合となる様に、反応容器に仕込んで反応させることにより製造することが出来る。本発明においては、前記した各単量体の反応率等は略同一と考えて、各単量体の仕込割合を、各単量体の重合単位の質量換算の含有割合と見なすものとする。モル換算の場合も同様である。本発明における共重合体（Ｂ）は、塊状重合、溶液重合、懸濁重合、乳化重合等の従来より公知の種々の反応方法によって合成することが出来る。この際には、公知慣用の重合開始剤や連鎖移動剤を併用することも出来る。 The copolymer (B) in the present invention can be produced by charging and reacting the respective monomers in a reaction vessel so that the content ratio of the respective polymerization units is obtained. In the present invention, the reaction rate of each monomer described above is considered to be substantially the same, and the charging ratio of each monomer is regarded as the content ratio of the polymerization unit of each monomer in terms of mass. The same applies to the case of molar conversion. The copolymer (B) in the present invention can be synthesized by various conventionally known reaction methods such as bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization. In this case, a known and usual polymerization initiator or chain transfer agent can be used in combination.
本発明における共重合体（Ｂ）は、（メタ）アクリル酸を共重合せしめた共重合体であるが、本発明の水性顔料分散体の調製に当たっては、そのカルボキシル基の少なくとも一部を後記塩基性物質（Ｃ）によってイオン化された形態とすることで、共重合体の水性媒体中への分散性や分散粒子の分散安定性を発現させる。イオン化されたカルボキシル基の最適割合は、通常３０〜１００％、特に７０〜１００％の範囲に設定されることが好ましい。このイオン化されたカルボキシル基の含有割合は、カルボキシル基と塩基性物質（Ｃ）のモル比を意味しているのではなく、解離平衡を考慮に入れたものである。カルボキシル基は、化学量論的に当量の強塩基性物質を用いても解離平衡によりイオン化された基（カルボキシラート基）の含有割合は１００％未満であって、カルボキシラート基とカルボキシル基の混在状態である。 The copolymer (B) in the present invention is a copolymer obtained by copolymerizing (meth) acrylic acid. In preparing the aqueous pigment dispersion of the present invention, at least a part of the carboxyl group is a base described later. By making the form ionized by the active substance (C), the dispersibility of the copolymer in the aqueous medium and the dispersion stability of the dispersed particles are expressed. The optimum proportion of ionized carboxyl groups is usually set in the range of 30 to 100%, particularly 70 to 100%. The content ratio of the ionized carboxyl group does not mean the molar ratio of the carboxyl group to the basic substance (C) but takes into account the dissociation equilibrium. Even if a stoichiometrically equivalent strong basic substance is used, the carboxyl group has a content of groups ionized by dissociation equilibrium (carboxylate group) of less than 100%, and the carboxylate group and carboxyl group are mixed. State.
共重合体（Ｂ）におけるスチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル数、この合計モル数に対するスチレン系単量体のモル％、併用したその他の共重合可能なエチレン性不飽和単量体の種類や量、共重合体の分子量及び酸価等が一定の条件のもとでの対比では、共重合体（Ｂ）中のカルボキシル基をイオン化させるための塩基性物質（Ｃ）の使用量が少ない程、着色画像の耐水性や着色画像濃度は向上する傾向にあるが、一方で、分散粒子の分散安定性が低下する傾向にある。従って、塩基性物質（Ｃ）の使用量は、用いる共重合体（Ｂ）の酸価と合わせて、これら特性がバランスする様に使用量を選択することが好ましい。 Total number of moles of styrene monomer and benzyl (meth) acrylate monomer in copolymer (B), mole% of styrene monomer relative to the total mole number, and other copolymerizations that can be used together The base for ionizing the carboxyl group in the copolymer (B) when comparing the type and amount of the ethylenically unsaturated monomer, the molecular weight of the copolymer and the acid value, etc. The smaller the amount of the active substance (C) used, the more the water resistance and the color image density of the colored image tend to be improved. On the other hand, the dispersion stability of the dispersed particles tends to be lowered. Therefore, it is preferable that the amount of the basic substance (C) used is selected so that these characteristics are balanced, together with the acid value of the copolymer (B) to be used.
この様に、共重合体（Ｂ）のカルボキシル基の少なくとも一部をイオン化するために用いられる塩基性物質（Ｃ）としては、公知慣用のものがいずれも使用出来る。この様な塩基性化合物（Ｃ）としては、例えば、アンモニア、第一級アミン、第二級アミン、第三級アミン等の有機アミン、アルカリ金属水酸化物からなる群から選ばれる化合物が挙げられる。尚、本発明において、塩基性含窒素複素環化合物は、第三級アミンとする。 Thus, as the basic substance (C) used for ionizing at least a part of the carboxyl group of the copolymer (B), any known and commonly used substances can be used. Examples of such a basic compound (C) include compounds selected from the group consisting of organic amines such as ammonia, primary amines, secondary amines and tertiary amines, and alkali metal hydroxides. . In the present invention, the basic nitrogen-containing heterocyclic compound is a tertiary amine.
塩基性物質（Ｃ）で共重合体（Ｂ）のカルボキシル基の少なくとも一部をイオン化することにより、カルボキシラート基の対イオンは、アンモニウムイオン又はアルカリ金属イオンからなる群から選ばれるカチオンとなる。尚、本発明において塩基性化合物（Ｃ）として塩基性含窒素複素環化合物を用いた場合には、前記複素環化合物は、塩基性含窒素複素環化合物のプロトン化カチオンとなる。 By ionizing at least part of the carboxyl group of the copolymer (B) with the basic substance (C), the counter ion of the carboxylate group becomes a cation selected from the group consisting of ammonium ions or alkali metal ions. In the present invention, when a basic nitrogen-containing heterocyclic compound is used as the basic compound (C), the heterocyclic compound becomes a protonated cation of the basic nitrogen-containing heterocyclic compound.
塩基性物質（Ｃ）として、例えば、水酸化ナトリウムや水酸化カリウムの様なアルカリ金属水酸化物を用いた場合には、アンモニアや前記有機アミンを用いた場合に比べて、水性顔料分散体中の分散粒子の分散安定性が良好となるので好ましい。 As the basic substance (C), for example, when an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is used, the aqueous pigment dispersion is used as compared with the case where ammonia or the organic amine is used. This is preferable because the dispersion stability of the dispersed particles becomes good.
アンモニアや前記有機アミンを用いた場合は、低温においてそれらが揮発性に優れるため、水性顔料分散体及び水性顔料記録液の被記録媒体上の着色画像の乾燥性や、インクジェット記録用水性インクの調製直後の吐出安定性に優れる。 When ammonia or the above organic amines are used, they are excellent in volatility at low temperatures. Therefore, the dryness of the colored image on the recording medium of the aqueous pigment dispersion and the aqueous pigment recording liquid, and the preparation of the aqueous ink for inkjet recording Excellent discharge stability immediately after.
しかしながら、一方でアンモニアや前記有機アミンは、長時間放置及び／又は高温雰囲気下で揮散するため、水性顔料分散体及びインクジェット記録用水性インク中の分散粒子の分散安定性が徐々に損なわれていき、分散粒子の沈降が観察される場合がある。この様な水性顔料分散体からそのままインクジェット記録用水性インクを調製した場合には、インク中の沈降した粒子がプリンターのノズルからのインク液滴の吐出不良を引き起こす原因となるので好ましくない。 On the other hand, however, ammonia and the organic amine volatilize when left for a long time and / or in a high-temperature atmosphere, so that the dispersion stability of the dispersed particles in the aqueous pigment dispersion and the aqueous ink for inkjet recording is gradually impaired. In some cases, sedimentation of dispersed particles is observed. If an aqueous ink for inkjet recording is prepared as it is from such an aqueous pigment dispersion, the settled particles in the ink cause a discharge failure of ink droplets from the nozzles of the printer, which is not preferable.
本発明において最適な共重合体（Ｂ）は、塩基性物質（Ｃ）によりカルボキシル基の一部が中和された、カルボキシル基及びカルボキシラート基の両方を含有するスチレン−アクリル共重合体である。 The most suitable copolymer (B) in the present invention is a styrene-acrylic copolymer containing both a carboxyl group and a carboxylate group, wherein a part of the carboxyl group is neutralized by the basic substance (C). .
本発明における共重合体（Ｂ）は、モノエチレン性不飽和単量体のみを重合して得られた線状の（リニアー）スチレン−アクリル系共重合体であることが、水性媒体への良好な分散性及び低粘度の水性顔料分散体を得る上では好ましい。しかしながら、前記特性を損なわない範囲において、共重合体（Ｂ）は必要ならば架橋部分を含有していても良い。共重合体（Ｂ）に架橋部分を含有させるには、前記その他の共重合可能なエチレン性不飽和単量体として、例えば、（メタ）アクリル酸２，３−エポキシプロピルの様なエポキシ基を含有するモノエチレン性不飽和単量体や、ジビニルベンゼンの様な２以上のエチレン性不飽和二重結合を含有する単量体を、前記４種の必須のモノエチレン性不飽和単量体に極少量併用する様にして重合する。 The copolymer (B) in the present invention is preferably a linear (linear) styrene-acrylic copolymer obtained by polymerizing only a monoethylenically unsaturated monomer. Is preferable for obtaining an aqueous pigment dispersion having a high dispersibility and a low viscosity. However, the copolymer (B) may contain a cross-linked portion if necessary, as long as the above properties are not impaired. In order to contain a crosslinked part in the copolymer (B), as the other copolymerizable ethylenically unsaturated monomer, for example, an epoxy group such as 2,3-epoxypropyl (meth) acrylate is used. The above four essential monoethylenically unsaturated monomers include monoethylenically unsaturated monomers and monomers containing two or more ethylenically unsaturated double bonds such as divinylbenzene. Polymerize in a very small amount.
エポキシ基を含有するモノエチレン性不飽和単量体の重合単位を含有する共重合体（Ｂ）の場合は、このエポキシ基を開環反応させて架橋を行う。エポキシ基の架橋に必要ならば硬化触媒を併用しても良い。 In the case of the copolymer (B) containing a polymerized unit of a monoethylenically unsaturated monomer containing an epoxy group, the epoxy group is subjected to a ring-opening reaction to carry out crosslinking. If necessary for crosslinking of the epoxy group, a curing catalyst may be used in combination.
本発明の水性顔料分散体は、例えば、後記する様な１）〜４）の方法で製造することが出来る。
１）共重合体（Ｂ）と塩基性物質（Ｃ）とを含有する水性エマルジョンに顔料（Ａ）を機械的に強制分散する水性顔料分散体の製造方法。
２）顔料（Ａ）の存在下の水中で分散剤と塩基性物質（Ｃ）とを用いて前記した各単量体を重合させ共重合体（Ｂ）とし必要に応じて会合させる水性顔料分散体の製造方法。
３）顔料（Ａ）と共重合体（Ｂ）と有機溶剤の混合物を、水と塩基性物質（Ｃ）を用いて徐徐に油相から水相に転相させてから脱溶剤する水性顔料分散体の製造方法。
４）顔料（Ａ）と共重合体（Ｂ）と塩基性物質（Ｃ）と有機溶剤と水との均一混合物から脱溶剤を行い、酸性物質を加えて酸析し析出物を洗浄後、この析出物を塩基性物質（Ｃ）と共に水性媒体に分散させる水性顔料分散体の製造方法。
The aqueous pigment dispersion of the present invention can be produced, for example, by the methods 1) to 4) as described later.
1) A method for producing an aqueous pigment dispersion in which the pigment (A) is mechanically and forcedly dispersed in an aqueous emulsion containing the copolymer (B) and the basic substance (C).
2) Aqueous pigment dispersion in which the above-mentioned monomers are polymerized by using a dispersant and a basic substance (C) in water in the presence of the pigment (A) to form a copolymer (B) and associate as necessary. Body manufacturing method.
3) Aqueous pigment dispersion in which a mixture of the pigment (A), the copolymer (B) and the organic solvent is gradually phase-inverted from the oil phase to the aqueous phase using water and a basic substance (C), and then the solvent is removed. Body manufacturing method.
4) The solvent is removed from a uniform mixture of the pigment (A), the copolymer (B), the basic substance (C), the organic solvent and water, the acid substance is added, the acid is precipitated, and the precipitate is washed. A method for producing an aqueous pigment dispersion in which a precipitate is dispersed in an aqueous medium together with a basic substance (C).
前記した通り、本発明の水性顔料分散体において、分散粒子は、顔料（Ａ）と共重合体（Ｂ）との相互作用が強く働いているものの方が分散安定性性等の点で好ましく、前記方法３）及び４）により製造される水性顔料分散体は、前記方法１）及び２）により製造される水性顔料分散体に比べ、分散粒子の分散安定性が高いだけでなく、水性顔料分散体の粘度もより低くなるので好ましい。インクジェット記録方式では、ノズルからインク液滴を飛ばすためにはそれが低粘度であることが望まれることから、それを調製するための水性顔料分散体自体の粘度も低いことが好まれる。 As described above, in the aqueous pigment dispersion of the present invention, the dispersed particles preferably have a strong interaction with the pigment (A) and the copolymer (B) in terms of dispersion stability, The aqueous pigment dispersions produced by the above methods 3) and 4) have not only high dispersion stability of dispersed particles but also aqueous pigment dispersions compared to the aqueous pigment dispersions produced by the above methods 1) and 2). It is preferable because the viscosity of the body is lower. In the ink jet recording system, in order to eject ink droplets from a nozzle, it is desired that the ink droplet has a low viscosity. Therefore, it is preferable that the viscosity of the aqueous pigment dispersion itself for preparing it is also low.
本発明では、前記いずれの製造方法をとるにせよ、顔料（Ａ）、共重合体（Ｂ）、塩基性物質（Ｃ）及び水性媒体からなる混合物を分散する工程を必須として含ませることが好ましい。この混合物には水溶性有機溶剤を含有させるのが好ましい。より具体的には、少なくとも顔料（Ａ）、共重合体（Ｂ）、塩基性物質（Ｃ）、水溶性有機溶剤及び水からなる混合物を分散する工程（分散工程）を含ませることが好ましい。水に水溶性有機溶剤を併用することにより分散工程における液粘度を低下させることが出来る場合がある。 In the present invention, it is preferable to include the step of dispersing the mixture comprising the pigment (A), the copolymer (B), the basic substance (C), and the aqueous medium, regardless of which production method is used. . This mixture preferably contains a water-soluble organic solvent. More specifically, it is preferable to include a step (dispersing step) of dispersing a mixture of at least the pigment (A), the copolymer (B), the basic substance (C), the water-soluble organic solvent, and water. By using a water-soluble organic solvent in combination with water, the liquid viscosity in the dispersion step may be reduced.
水溶性有機溶剤としては、例えば、アセトン、メチルエチルケトン、メチルブチルケトン、メチルイソブチルケトン、等のケトン類；メタノール、エタノール、２−プロパノール、２−メチル−１−プロパノール、１−ブタノール、２−メトキシエタノール、等のアルコール類；テトラヒドロフラン、１，４−ジオキサン、１，２−ジメトキシエタン、等のエーテル類；ジメチルホルムアミド、Ｎ−メチルピロリドン、等のアミド類が挙げられ、とりわけ炭素数が３〜６のケトン及び炭素数が１〜５のアルコールからなる群から選ばれる化合物を用いるのが好ましい。これらの水溶性有機溶剤は、前記共重合体（Ｂ）溶液として用いられても良く、別途独立に分散工程中において前記混合物中に含有させても良い。 Examples of the water-soluble organic solvent include ketones such as acetone, methyl ethyl ketone, methyl butyl ketone, and methyl isobutyl ketone; methanol, ethanol, 2-propanol, 2-methyl-1-propanol, 1-butanol, and 2-methoxyethanol. Alcohols such as tetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, etc .; amides such as dimethylformamide, N-methylpyrrolidone, etc., and especially those having 3 to 6 carbon atoms It is preferable to use a compound selected from the group consisting of a ketone and an alcohol having 1 to 5 carbon atoms. These water-soluble organic solvents may be used as the copolymer (B) solution, or may be separately contained in the mixture during the dispersion step.
本発明の水性顔料分散体は、質量換算で、顔料（Ａ）／共重合体（Ｂ）（不揮発分換算）＝１００／１０〜１００／１００とするのが好ましい。最適には、質量換算で顔料（Ａ）１００部当たり、共重合体（Ｂ）の不揮発分２０〜６５部かつ水性媒体８３５〜８８０部となる様に、前記した原料を用いて製造することが出来る。 The aqueous pigment dispersion of the present invention preferably has a pigment (A) / copolymer (B) (nonvolatile content) = 100/10 to 100/100 in terms of mass. Optimally, it is produced using the above-described raw materials so that the non-volatile content of the copolymer (B) is 20 to 65 parts and the aqueous medium is 835 to 880 parts per 100 parts of the pigment (A) in terms of mass. I can do it.
分散工程において用いることの出来る分散装置としては、既に公知の種々の方式による装置がいずれも使用出来、特に限定されるものではない。この様な分散装置としては、例えば、スチール、ステンレス、ジルコニア、アルミナ、窒化ケイ素、ガラス等でできた直径０．１〜１０ｍｍ程度の球状分散媒体の運動エネルギーを利用する方式、機械的攪拌による剪断力を利用する方式、高速で供給された被分散物流束の圧力変化、流路変化あるいは衝突に伴って発生する力を利用する方式、等の分散方式の分散装置を挙げることが出来る。 As a dispersion apparatus that can be used in the dispersion step, any of various known apparatuses can be used and is not particularly limited. Examples of such a dispersing device include a method using kinetic energy of a spherical dispersion medium having a diameter of about 0.1 to 10 mm made of steel, stainless steel, zirconia, alumina, silicon nitride, glass, etc., shearing by mechanical stirring. Examples of the dispersion device include a dispersion method such as a force utilization method, a pressure change of a dispersed flow bundle supplied at high speed, a flow passage change, or a force utilization force generated by a collision.
こうした分散工程を実施することで、共重合体（Ｂ）を含有する液媒体中に顔料（Ａ）が分散した状態が形成される。またこうした分散工程において塩基性物質（Ｃ）をより多くの量用いることで、液媒体中に含有する共重合体（Ｂ）を分散状態から溶解状態とすることも出来る。 By carrying out such a dispersion step, a state in which the pigment (A) is dispersed in the liquid medium containing the copolymer (B) is formed. Further, by using a larger amount of the basic substance (C) in such a dispersion step, the copolymer (B) contained in the liquid medium can be changed from a dispersed state to a dissolved state.
分散工程に引き続き、分散工程において有機溶剤を使用した場合に、これを除去する工程、所望の固形分濃度にするため余剰の水を除去する工程（蒸留工程）を実施することが出来る。本発明の水性顔料分散体としては有機溶剤を含まないものが臭気がなく、作業環境を良好と出来る点で好ましい。 Subsequent to the dispersion step, when an organic solvent is used in the dispersion step, a step of removing the organic solvent and a step of removing excess water (distillation step) to obtain a desired solid concentration can be performed. As the aqueous pigment dispersion of the present invention, those containing no organic solvent are preferred because they have no odor and can improve the working environment.
本発明の水性顔料分散体は、分散到達レベル、分散所要時間及び分散安定性の全ての面で、より優れた特性を発揮させるに当たって、顔料（Ａ）と共重合体（Ｂ）とは、より相互作用が強く働き分散していることが好ましい。 In the aqueous pigment dispersion of the present invention, the pigment (A) and the copolymer (B) are more effective in exhibiting more excellent characteristics in all aspects of dispersion attainment level, required dispersion time and dispersion stability. It is preferable that the interaction is strong and dispersed.
分散粒子の相互作用を高めるため、溶解状態にある共重合体（Ｂ）に顔料（Ａ）表面を密着させる工程を、前記分散工程の後工程として組み込むことが好ましい。 In order to enhance the interaction of the dispersed particles, it is preferable to incorporate a step of bringing the pigment (A) surface into close contact with the copolymer (B) in a dissolved state as a subsequent step of the dispersing step.
溶解状態にある共重合体（Ｂ）を顔料（Ａ）表面に密着させる工程としては、顔料（Ａ）と塩基性物質（Ｃ）により溶解している共重合体（Ｂ）とを含有する液媒体を酸性化することにより、共重合体（Ｂ）中のアニオン性基を中和される前の官能基に戻して、共重合体（Ｂ）を析出させる工程（酸析工程）が好ましい。 The step of bringing the copolymer (B) in a dissolved state into close contact with the surface of the pigment (A) includes a liquid containing the pigment (A) and the copolymer (B) dissolved by the basic substance (C). A step of acidifying the medium to return the anionic group in the copolymer (B) to the functional group before being neutralized and precipitating the copolymer (B) (acid precipitation step) is preferable.
酸析工程は、前記分散工程と必要に応じて実施される蒸留工程を経て得られた水性顔料分散体に塩酸、硫酸、酢酸等の酸性物質を加えて酸性化し、塩基性物質（Ｃ）と塩を形成することによって溶解状態にある共重合体（Ｂ）を顔料（Ａ）粒子表面に析出させる工程である。この工程により、顔料（Ａ）と共重合体（Ｂ）との相互作用を高めることが出来る。こうして相互作用を高めて得られた析出物を濾別後、より好ましくはその析出物を洗浄してから、再度塩基性物質（Ｃ）と共に水性媒体に分散させることで、より分散安定性に優れた水性顔料分散体とすることが出来る。 In the acid precipitation process, an acidic substance such as hydrochloric acid, sulfuric acid, acetic acid or the like is added to the aqueous pigment dispersion obtained through the dispersion process and the distillation process carried out as necessary to acidify the basic substance (C). In this step, the copolymer (B) in a dissolved state is precipitated on the surface of the pigment (A) particles by forming a salt. By this step, the interaction between the pigment (A) and the copolymer (B) can be enhanced. After separating the precipitate obtained by enhancing the interaction in this way, more preferably, the precipitate is washed, and then dispersed again in an aqueous medium together with the basic substance (C), so that the dispersion stability is further improved. Water-based pigment dispersion.
濾過工程は、顔料（Ａ）と共重合体（Ｂ）との相互作用を高めて得られた析出物を濾別する工程である。この析出物は顔料（Ａ）と共重合体（Ｂ）とからなる固形分である。この工程は前記した酸析工程後の固形分をフィルタープレス、ヌッチェ式濾過装置、加圧濾過装置等により濾過する工程である。 The filtration step is a step of separating the precipitate obtained by enhancing the interaction between the pigment (A) and the copolymer (B). This deposit is a solid content composed of the pigment (A) and the copolymer (B). This step is a step of filtering the solid content after the acid precipitation step with a filter press, a Nutsche filtration device, a pressure filtration device or the like.
洗浄工程は、前記濾過工程で濾別された析出物を洗浄濾過する工程であり、この工程を実施することにより、最終的に得られる水性顔料分散体に含有する無機塩類の低減又は除去が可能になる。市販の有機顔料は、無機塩類を多量に含有している場合があり、この様な有機顔料を用いて調製した水性顔料分散体から得られるインクジェット記録用水性インクは、それによるプリンターノズルの目詰まり等による吐出不良が起こり易い。しかしながら、前記洗浄工程を経た水性顔料分散体から水性顔料記録液を調製することで、この問題は解消される。 The washing step is a step of washing and filtering the precipitate separated in the filtration step. By performing this step, inorganic salts contained in the finally obtained aqueous pigment dispersion can be reduced or removed. become. Commercially available organic pigments may contain a large amount of inorganic salts, and aqueous inks for ink jet recording obtained from aqueous pigment dispersions prepared using such organic pigments may clog printer nozzles. Ejection failure due to etc. is likely to occur. However, this problem can be solved by preparing an aqueous pigment recording liquid from the aqueous pigment dispersion that has undergone the washing step.
前記方法４）に従って水性顔料分散体を製造する場合には、市販の有機顔料に含有する無機塩類とその他の要因で混入してきた無機塩類とをこの洗浄工程で一括して低減又は除去出来ることから、その他の製造方法において前記同様の問題が発生した際に必要となる、有機顔料自体の事前洗浄を独立して行う必要がなく、単位操作がより簡便で済むという長所がある。 When an aqueous pigment dispersion is produced according to the above method 4), inorganic salts contained in commercially available organic pigments and inorganic salts mixed due to other factors can be collectively reduced or removed in this washing step. In addition, there is an advantage that the unit operation is simpler because it is not necessary to independently perform the pre-cleaning of the organic pigment itself, which is necessary when the same problem occurs in other production methods.
再分散工程は、前記酸析工程、濾過工程によって得られた固形分に塩基性物質（Ｃ）及び必要により水や添加物を加えて、再び水性顔料分散体とする工程である。この工程では、共重合体（Ｂ）中のイオン化したカルボキシル基の対イオンを分散工程で用いた塩基性物質（Ｃ）とは別の塩基性物質（Ｃ）に変更することが出来る。 The redispersion step is a step in which the basic substance (C) and, if necessary, water and additives are added to the solid content obtained by the acid precipitation step and the filtration step to form an aqueous pigment dispersion again. In this step, the counter ion of the ionized carboxyl group in the copolymer (B) can be changed to a basic material (C) different from the basic material (C) used in the dispersion step.
酸析工程と再分散工程を必須の工程として、好ましくは濾過工程と洗浄工程をも含む製造方法で水性顔料分散体を製造すると、分散粒子として前記した様に顔料（Ａ）と共重合体（Ｂ）との相互作用がより高まった状態を容易に形成させることができ、水性顔料分散体として、分散到達レベルや分散安定性等の物性面や耐溶剤性等の使用適性の面で、より優れた特性を発揮させることが出来る。 When the aqueous pigment dispersion is produced by a production method including an acid precipitation step and a redispersion step as essential steps, preferably including a filtration step and a washing step, the pigment (A) and copolymer ( B) can be easily formed in a state of further interaction with the aqueous pigment dispersion, more in terms of physical properties such as dispersion reach level and dispersion stability, and suitability for use such as solvent resistance. Excellent characteristics can be exhibited.
こうして得られた本発明の水性顔料分散体に、例えば、水性ポリウレタン、水性ポリエステル、水性アクリルからなる群から選ばれる少なくとも１種の水性樹脂を添加することも出来る。ここで水性樹脂とは、界面活性剤等を含ませなくてもそれ自体で水性媒体中に分散しうる樹脂が好ましい。この様な水性ポリウレタンは、ジメチロールプロピオン酸とジオールと有機ジイソシアネートと必要に応じてジアミンを組み合わせて重付加反応させカルボキシル基含有ポリウレタンとしこれを前記した様な塩基性物質（Ｃ）で中和することで製造出来るし、水性ポリエステルは、トリメリット酸、ピロメリット酸、スルホコハク酸及びこれらの誘導体とジオールとジカルボン酸とを組み合わせてエステル化或いはエステル交換反応させカルボキシル基又はスルホ基含有ポリエステルとしこれを前記した様な塩基性物質（Ｃ）で中和することで製造出来るし、水性アクリルは、（メタ）アクリル酸をその他の共重合可能なモノエチレン性不飽和単量体と共重合反応させカルボキシル基含有アクリル樹脂としこれを前記した様な塩基性物質（Ｃ）で中和することで製造出来る。 For example, at least one aqueous resin selected from the group consisting of aqueous polyurethane, aqueous polyester and aqueous acrylic can be added to the aqueous pigment dispersion of the present invention thus obtained. Here, the aqueous resin is preferably a resin that itself can be dispersed in an aqueous medium without containing a surfactant or the like. Such an aqueous polyurethane is subjected to a polyaddition reaction by combining dimethylolpropionic acid, a diol, an organic diisocyanate and, if necessary, a diamine to obtain a carboxyl group-containing polyurethane, which is neutralized with the basic substance (C) as described above. The aqueous polyester is trimesteric acid, pyromellitic acid, sulfosuccinic acid and their derivatives combined with diol and dicarboxylic acid to be esterified or transesterified to form a carboxyl group or sulfo group-containing polyester. It can be produced by neutralization with the basic substance (C) as described above, and aqueous acrylic can be obtained by copolymerizing (meth) acrylic acid with other copolymerizable monoethylenically unsaturated monomers. As a group-containing acrylic resin, the basic substance (C In can be produced by neutralization.
この水性樹脂の分散粒子は、平均分散粒径（メディアン径）１０〜１００ｎｍの範囲でベースとなる前記水性顔料分散体中の分散粒子のそれよりも相対的に小さいものであることが好ましい。本発明の水性顔料分散体へのこれら水性樹脂の添加は、写真用紙の様なインクジェット専用紙における指触時の耐擦過性を向上させる効果がある。これら水性樹脂の中では、水性ポリウレタンが指触時の耐擦過性を向上させる効果がより大きいので好ましい。指触時の耐擦過性とは、被記録媒体上の着色画像を印字直後から一定時間毎に指で擦った時の色の滲み方を意味する。水性ポリウレタンの添加は、印字直後から印字１０分後の耐擦過性の改良に効果的である。 It is preferable that the dispersed particles of the aqueous resin are relatively smaller than those of the dispersed particles in the aqueous pigment dispersion serving as a base in the range of an average dispersed particle diameter (median diameter) of 10 to 100 nm. The addition of these water-based resins to the water-based pigment dispersion of the present invention has an effect of improving the scratch resistance at the time of finger touching on an inkjet exclusive paper such as a photographic paper. Among these water-based resins, water-based polyurethane is preferable because it has a greater effect of improving scratch resistance when touched with a finger. Scratch resistance at the time of touching means the color bleeding when a colored image on a recording medium is rubbed with a finger at regular intervals immediately after printing. The addition of water-based polyurethane is effective in improving the scratch resistance immediately after printing and 10 minutes after printing.
こうした水性ポリウレタンとしては、例えば、ポリエステル系ポリウレタン、ポリエーテル系ポリウレタン、ポリエーテルエステル系ポリウレタン、ポリカーボネート系ポリウレタン等が挙げられる。これらは前記した製造方法において、ジオールとして、ポリエステルジオール、ポリエーテルジオール等対応する高分子ジオールを用いることにより容易に得られる。 Examples of such an aqueous polyurethane include polyester-based polyurethane, polyether-based polyurethane, polyetherester-based polyurethane, and polycarbonate-based polyurethane. These can be easily obtained by using a corresponding polymer diol such as polyester diol or polyether diol as the diol in the production method described above.
前記した水性樹脂は、顔料（Ａ）１００部当たり不揮発分の質量換算で５〜３０部となる様に本発明の水性顔料分散体に添加することが出来る。この水性樹脂は本発明の水性顔料分散体に添加してからインクジェット記録用水性インクを調製する様にしても良いが、本発明の水性顔料分散体からインクジェット記録用水性インクを調製してから、そこにこの水性樹脂を前記した量となる様に添加することも出来る。 The above-mentioned aqueous resin can be added to the aqueous pigment dispersion of the present invention so as to be 5 to 30 parts in terms of non-volatile content per 100 parts of the pigment (A). This aqueous resin may be added to the aqueous pigment dispersion of the present invention to prepare an aqueous ink for inkjet recording, but after preparing the aqueous ink for inkjet recording from the aqueous pigment dispersion of the present invention, The aqueous resin can be added to the above amount.
本発明のインクジェット記録用水性インクは、本発明の水性顔料分散体を含むものである。この様なインクジェット記録用水性インクは、質量換算による分散粒子含有率１〜１０％となる様に水性顔料分散体を調製することが出来る。この際には、前記した分散粒子含有率を越える、濃厚な水性顔料分散体に対して必要に応じて水や水溶性有機溶剤を加えて、前記範囲で必要な分散粒子含有率となる様に希釈したり、湿潤剤、防かび剤、ｐＨ調節剤等の水性インクの調製に必要な各種添加剤を併用することが出来る。また得られたインクジェット記録用水性インクは、必要に応じてミクロフィルターにより濾過をすることにより、ノズル目詰まり等の極めて少なくすることが出来る。 The aqueous ink for inkjet recording of the present invention contains the aqueous pigment dispersion of the present invention. In such a water-based ink for ink-jet recording, an aqueous pigment dispersion can be prepared such that the content of dispersed particles in terms of mass is 1 to 10%. At this time, if necessary, water or a water-soluble organic solvent is added to the concentrated aqueous pigment dispersion exceeding the above-mentioned dispersed particle content so that the required dispersed particle content is within the above range. Various additives necessary for the preparation of water-based inks such as a diluting agent, a wetting agent, an antifungal agent, and a pH adjusting agent can be used in combination. Further, the obtained water-based ink for ink-jet recording can be extremely reduced such as nozzle clogging by filtering with a microfilter if necessary.
また、吐出方式に応じて組成を適宜選択し調製することにより、本発明の水性顔料分散体から、ピエゾ方式でもサーマル方式でもいずれの方式にも対応出来るインクジェット記録用水性インクを得ることが出来る。本発明のインクジェット記録用水性インクは、公知慣用の被記録媒体への記録に使用することが出来る。この様な被記録媒体としては、例えば普通紙、樹脂コート紙、混抄紙、合成樹脂フィルム等が挙げられる。中でも、本発明のインクジェット記録用水性インクは、写真用紙の様なインクジェット専用紙においてより光沢の高い着色画像が得られるか、又は普通紙においてより鮮明な発色濃度が高い着色画像が得られる。特に被記録媒体の普通紙としては、針葉樹パルプを原料とした太い繊維を抄紙した普通紙が、この発色性の改良効果が最も大きい。 Further, by appropriately selecting and preparing the composition according to the ejection method, it is possible to obtain an aqueous ink for ink jet recording that can be applied to either the piezo method or the thermal method from the aqueous pigment dispersion of the present invention. The water-based ink for ink jet recording of the present invention can be used for recording on a known and commonly used recording medium. Examples of such a recording medium include plain paper, resin-coated paper, mixed paper, and synthetic resin film. Among these, the water-based ink for inkjet recording of the present invention can give a colored image with higher gloss on an inkjet-only paper such as a photographic paper, or a colored image with a clearer color density on plain paper. In particular, as a plain paper for recording media, plain paper made of thick fibers made from conifer pulp is the most effective in improving color development.
以下の合成例、実施例及び比較例において、「部」及び「％」は、いずれも質量換算である。 In the following synthesis examples, examples and comparative examples, “parts” and “%” are all in terms of mass.
［合成例１］
攪拌装置、滴下装置、温度センサー、及び上部に窒素導入装置を有する環流装置を取り付けた反応容器を有する自動重合反応装置〔重合試験機ＤＳＬ−２ＡＳ型、轟産業（株）製〕の反応容器にメチルエチルケトン１，１００部を仕込み、攪拌しながら反応容器内を窒素置換した。反応容器内を窒素雰囲気に保ちながら８０℃に昇温させた後、滴下装置よりメタクリル酸ブチル６５部、アクリル酸ブチル２２２部、メタクリル酸２−ヒドロキシエチル７５部、メタクリル酸１３８部、スチレン２００部、メタクリル酸ベンジル３００部及び「パーブチル（登録商標）Ｏ」〔有効成分ペルオキシ２−エチルヘキサン酸ｔ−ブチル、日本油脂（株）製〕８０部の混合液を４時間かけて滴下した。滴下終了後、さらに同温度で１５時間反応を継続させて、酸価９０、Ｔｇ３４℃、樹脂分４７．６％のスチレン−アクリル系共重合体（Ｂ−１）の溶液を得た〔スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル％＝４５モル％，スチレン系単量体のモル数／（スチレン系単量体のモル数と（メタ）アクリル酸ベンジル系単量体のモル数の和）＝５３％〕。
[Synthesis Example 1]
Methyl ethyl ketone is added to the reaction vessel of an automatic polymerization reactor [polymerization tester DSL-2AS type, manufactured by Sakai Sangyo Co., Ltd.] having a reaction vessel equipped with a stirring device, a dropping device, a temperature sensor, and a reflux device having a nitrogen introducing device at the top 1,100 parts were charged, and the inside of the reaction vessel was purged with nitrogen while stirring. After raising the temperature in the reaction vessel to 80 ° C. while maintaining a nitrogen atmosphere, 65 parts butyl methacrylate, 222 parts butyl acrylate, 75 parts 2-hydroxyethyl methacrylate, 138 parts methacrylic acid, 200 parts styrene from a dropping device. A mixture of 300 parts of benzyl methacrylate and 80 parts of “Perbutyl (registered trademark) O” (active ingredient t-butyl 2-ethylhexanoate, manufactured by NOF Corporation) was added dropwise over 4 hours. After completion of the dropwise addition, the reaction was further continued at the same temperature for 15 hours to obtain a solution of a styrene-acrylic copolymer (B-1) having an acid value of 90, Tg of 34 ° C. and a resin content of 47.6% [Styrene Total mol% of monomer and benzyl (meth) acrylate monomer = 45 mol%, number of moles of styrene monomer / (number of moles of styrene monomer and benzyl (meth) acrylate) Sum of moles of monomers) = 53%].
［合成例２］
メチルエチルケトン１，１００部を用い、かつメタクリル酸ブチル８７部、メタクリル酸２−ヒドロキシエチル７５部、メタクリル酸１３８部、スチレン３００部、メタクリル酸ベンジル４００部及び「パーブチル（登録商標）Ｏ」８０部の混合液を用いる以外は合成例１と同様の操作を行い、酸価９０、Ｔｇ７４℃、樹脂分４７．２％のスチレン−アクリル系共重合体（Ｂ−２）の溶液を得た〔スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル％＝６５モル％，スチレン系単量体のモル数／（スチレン系単量体のモル数と（メタ）アクリル酸ベンジル系単量体のモル数の和）＝５６％〕。
[Synthesis Example 2]
1,100 parts of methyl ethyl ketone, and 87 parts of butyl methacrylate, 75 parts of 2-hydroxyethyl methacrylate, 138 parts of methacrylic acid, 300 parts of styrene, 400 parts of benzyl methacrylate and 80 parts of “Perbutyl (registered trademark) O” The same operation as in Synthesis Example 1 was carried out except that the mixed solution was used to obtain a solution of a styrene-acrylic copolymer (B-2) having an acid value of 90, a Tg of 74 ° C., and a resin content of 47.2% [styrene system Total mol% of monomer and benzyl (meth) acrylate monomer = 65 mol%, number of moles of styrene monomer / (number of moles of styrene monomer and benzyl (meth) acrylate) Sum of the number of moles of monomers) = 56%].
［合成例３］
メチルエチルケトン１，１００部を用い、かつメタクリル酸２−ヒドロキシエチル７５部、メタクリル酸１３８部、スチレン４００部、メタクリル酸ベンジル３８７部及び「パーブチル（登録商標）Ｏ」８０部の混合液を用いる以外は合成例１と同様の操作を行い、酸価９０、Ｔｇ８２℃、樹脂分４７．１％のスチレン−アクリル系共重合体（Ｂ−３）の溶液を得た〔スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル％＝７３モル％，スチレン系単量体のモル数／（スチレン系単量体のモル数と（メタ）アクリル酸ベンジル系単量体のモル数の和）＝６４％〕。
[Synthesis Example 3]
Except for using 1,100 parts of methyl ethyl ketone and using a mixed solution of 75 parts of 2-hydroxyethyl methacrylate, 138 parts of methacrylic acid, 400 parts of styrene, 387 parts of benzyl methacrylate and 80 parts of “Perbutyl (registered trademark) O”. The same operation as in Synthesis Example 1 was performed to obtain a solution of a styrene-acrylic copolymer (B-3) having an acid value of 90, Tg of 82 ° C., and a resin content of 47.1% [styrene monomer and (meta ) Total mol% with benzyl acrylate monomer = 73 mol%, mol number of styrene monomer / (mol number of styrene monomer and mol number of benzyl (meth) acrylate monomer) (Sum of) = 64%].
［合成例４］
メチルエチルケトン１，１００部を用い、かつメタクリル酸２−ヒドロキシエチル７５部、メタクリル酸１３８部、スチレン５００部、メタクリル酸ベンジル２８７部及び「パーブチル（登録商標）Ｏ」８０部の混合液を用いる以外は合成例１と同様の操作を行い、酸価９０、Ｔｇ８７℃、樹脂分４６．１％のスチレン−アクリル系共重合体（Ｂ−４）の溶液を得た〔スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル％＝７５モル％，スチレン系単量体のモル数／（スチレン系単量体のモル数と（メタ）アクリル酸ベンジル系単量体のモル数の和）＝７５％〕。
[Synthesis Example 4]
Except for using 1,100 parts of methyl ethyl ketone and using a mixed solution of 75 parts of 2-hydroxyethyl methacrylate, 138 parts of methacrylic acid, 500 parts of styrene, 287 parts of benzyl methacrylate and 80 parts of “Perbutyl (registered trademark) O”. The same operation as in Synthesis Example 1 was performed to obtain a solution of a styrene-acrylic copolymer (B-4) having an acid value of 90, Tg of 87 ° C., and a resin content of 46.1% [styrene monomer and (meta ) Total mol% with benzyl acrylate monomer = 75 mol%, number of moles of styrene monomer / (number of moles of styrene monomer and moles of benzyl (meth) acrylate monomer) Of sum) = 75%].
［合成例５］
メチルエチルケトン１，１００部を用い、かつブチルアクリレート２８７部、メタクリル酸２−ヒドロキシエチル７５部、メタクリル酸１３８部、スチレン４００部、メタクリル酸ベンジル１００部及び「パーブチル（登録商標）Ｏ」８０部の混合液を用いる以外は合成例１と同様の操作を行い、酸価９０、Ｔｇ３４℃、樹脂分４６．９％のスチレン−アクリル系共重合体（Ｂ−５）の溶液を得た〔スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル％＝５０モル％，スチレン系単量体のモル数／（スチレン系単量体のモル数と（メタ）アクリル酸ベンジル系単量体のモル数の和）＝８７％〕。
[Synthesis Example 5]
1,100 parts of methyl ethyl ketone and 287 parts of butyl acrylate, 75 parts of 2-hydroxyethyl methacrylate, 138 parts of methacrylic acid, 400 parts of styrene, 100 parts of benzyl methacrylate and 80 parts of “Perbutyl (registered trademark) O” The same operation as in Synthesis Example 1 was performed except that the solution was used to obtain a solution of a styrene-acrylic copolymer (B-5) having an acid value of 90, a Tg of 34 ° C., and a resin content of 46.9% [styrene-based monomer The total mol% of the monomer and benzyl (meth) acrylate monomer = 50 mol%, the number of moles of styrene monomer / (number of moles of styrene monomer and benzyl (meth) acrylate monomer) Sum of the number of moles of the monomer) = 87%].
［合成例６］（特許文献２の製造例１）
メチルエチルケトン１，１００部を用い、かつメタクリル酸ステアリル２００部、メタクリル酸１５３部、スチレン１５０部、メタクリル酸ベンジル４９７部及び「パーブチル （登録商標）Ｏ」８０部の混合液を用いる以外は合成例１と同様の操作を行い、酸価１００、Ｔｇ６７℃、樹脂分４７．１％のスチレン−アクリル系共重合体（Ｂ−６）の溶液を得た〔スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル％＝６４モル％，スチレン系単量体のモル数／（スチレン系単量体のモル数と（メタ）アクリル酸ベンジル系単量体のモル数の和）＝３４％〕。
[Synthesis Example 6] (Production Example 1 of Patent Document 2)
Synthesis Example 1 except that 1,100 parts of methyl ethyl ketone was used and a mixed solution of 200 parts of stearyl methacrylate, 153 parts of methacrylic acid, 150 parts of styrene, 497 parts of benzyl methacrylate and 80 parts of “Perbutyl (registered trademark) O” was used. The styrene-acrylic copolymer (B-6) solution having an acid value of 100, Tg of 67 ° C. and a resin content of 47.1% was obtained [styrene monomer and (meth) acrylic acid. Total mol% with benzyl monomer = 64 mol%, mole number of styrene monomer / (sum of moles of styrene monomer and moles of benzyl (meth) acrylate monomer) = 34%].
［合成例７］
メチルエチルケトン１，１００部を用い、かつメタクリル酸２−ヒドロキシエチル７５部、メタクリル酸ブチル１９部、アクリル酸ブチル２０７部、メタクリル酸１９９部、スチレン５００部、及び「パーブチル（登録商標）Ｏ」８０部の混合液を用いる以外は合成例１と同様の操作を行い、酸価１３０、Ｔｇ５３℃、樹脂分４８．９％のスチレン−アクリル系共重合体（Ｂ−７）の溶液を得た〔スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル％＝５１モル％，スチレン系単量体のモル数／（スチレン系単量体のモル数と（メタ）アクリル酸ベンジル系単量体のモル数の和）＝１００％〕。
[Synthesis Example 7]
1,100 parts of methyl ethyl ketone, and 75 parts of 2-hydroxyethyl methacrylate, 19 parts of butyl methacrylate, 207 parts of butyl acrylate, 199 parts of methacrylic acid, 500 parts of styrene, and 80 parts of “Perbutyl (registered trademark) O” The same procedure as in Synthesis Example 1 was performed except that a mixed solution of styrene-acrylic copolymer (B-7) having an acid value of 130, a Tg of 53 ° C., and a resin content of 48.9% was obtained [styrene. Total mol% of styrene monomer and benzyl (meth) acrylate monomer = 51 mol%, number of moles of styrene monomer / (number of moles of styrene monomer and benzyl (meth) acrylate Sum of moles of monomer) = 100%].
［合成例８］
メチルエチルケトン１，１００部を用い、かつメタクリル酸２−ヒドロキシエチル７５部、メタクリル酸ブチル５０３部、アクリル酸ブチル２３部、メタクリル酸１９９部、スチレン２００部、及び「パーブチル（登録商標）Ｏ」８０部の混合液を用いる以外は合成例１と同様の操作を行い、不揮発分を調製して酸価１３０、Ｔｇ５３℃、樹脂分４８．９％のスチレン−アクリル系共重合体（Ｂ−８）の溶液を得た〔スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル％＝２３モル％，スチレン系単量体のモル数／（スチレン系単量体のモル数と（メタ）アクリル酸ベンジル系単量体のモル数の和）＝１００％〕。
[Synthesis Example 8]
1,100 parts of methyl ethyl ketone, and 75 parts of 2-hydroxyethyl methacrylate, 503 parts of butyl methacrylate, 23 parts of butyl acrylate, 199 parts of methacrylic acid, 200 parts of styrene, and 80 parts of “Perbutyl (registered trademark) O” The same procedure as in Synthesis Example 1 was carried out except that a mixed solution of styrene-acrylic copolymer (B-8) having an acid value of 130, a Tg of 53 ° C., and a resin content of 48.9% was prepared. A solution was obtained [total mol% of styrene monomer and benzyl (meth) acrylate monomer = 23 mol%, mol of styrene monomer / (mol of styrene monomer and (The sum of the number of moles of the (meth) acrylic acid benzyl monomer) = 100%].
［合成例９］（特許文献２の製造例４に相当する合成例）
メチルエチルケトン１，１００部を用い、かつメタクリル酸ステアリル２００部、メタクリル酸３８３部、スチレン１５０部、メタクリル酸ベンジル２６７部、及び「パーブチル（登録商標）Ｏ」８０部の混合液を用いる以外は合成例１と同様の操作を行い、不揮発分を調製して酸価約２５０、Ｔｇ約８３℃、樹脂分４８．９％のスチレン−アクリル系共重合体（Ｂ−９）の溶液を得た〔スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル％＝３７モル％，スチレン系単量体のモル数／（スチレン系単量体のモル数と（メタ）アクリル酸ベンジル系単量体のモル数の和）＝４９％〕。
[Synthesis Example 9] (Synthesis Example corresponding to Production Example 4 of Patent Document 2)
Synthesis example except using 1,100 parts of methyl ethyl ketone, and using a mixed solution of 200 parts of stearyl methacrylate, 383 parts of methacrylic acid, 150 parts of styrene, 267 parts of benzyl methacrylate, and 80 parts of “Perbutyl (registered trademark) O” 1 to obtain a solution of a styrene-acrylic copolymer (B-9) having an acid value of about 250, a Tg of about 83 ° C., and a resin content of 48.9%. Total mol% of styrene monomer and benzyl (meth) acrylate monomer = 37 mol%, number of moles of styrene monomer / (number of moles of styrene monomer and benzyl (meth) acrylate Sum of the number of moles of the monomer) = 49%].
［合成例１０］（特許文献２の製造例７に相当する合成例）
メタクリル酸ステアリルに代えて同量のメタクリル酸ブチルを用いる以外は合成例６と同様の操作を行い、不揮発分を調製して酸価約１００、Ｔｇ約６３℃、樹脂分４８．９％のスチレン−アクリル系共重合体（Ｂ−１０）の溶液を得た〔スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル％＝５７モル％，スチレン系単量体のモル数／（スチレン系単量体のモル数と（メタ）アクリル酸ベンジル系単量体のモル数の和）＝３４％〕。
[Synthesis Example 10] (Synthesis Example corresponding to Production Example 7 of Patent Document 2)
Except for using the same amount of butyl methacrylate in place of stearyl methacrylate, the same operation as in Synthesis Example 6 was carried out to prepare a non-volatile content, styrene having an acid value of about 100, Tg of about 63 ° C., and a resin content of 48.9%. -A solution of an acrylic copolymer (B-10) was obtained [total mol% of styrene monomer and benzyl (meth) acrylate monomer = 57 mol%, mol of styrene monomer Number / (sum of moles of styrene monomer and moles of benzyl (meth) acrylate monomer) = 34%].
［合成例１１］
スチレン４０部とメタクリル酸ベンジル３８．７部に代えて７８．７部のメタクリル酸ベンジルを用いる以外は合成例３と同様の操作を行い、不揮発分を調製して酸価約９０、Ｔｇ約６４℃、樹脂分４８．９％のスチレン−アクリル系共重合体（Ｂ−１１）の溶液を得た〔スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル％＝６７モル％〕。
[Synthesis Example 11]
The same procedure as in Synthesis Example 3 was performed except that 78.7 parts of benzyl methacrylate was used instead of 40 parts of styrene and 38.7 parts of benzyl methacrylate. A solution of a styrene-acrylic copolymer (B-11) having a resin content of 48.9% was obtained [total mol% of styrene monomer and benzyl (meth) acrylate monomer = 67 Mol%].
これら各合成例１〜１１で合成された共重合体（Ｂ−１）〜共重合体（Ｂ−１１）の単量体組成を表１に、スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル％、スチレン系単量体のモル数／（スチレン系単量体のモル数と（メタ）アクリル酸ベンジル系単量体のモル数の和を表２に示した。 Table 1 shows monomer compositions of the copolymers (B-1) to (B-11) synthesized in each of these synthesis examples 1 to 11, and styrene monomers and benzyl (meth) acrylate. Table 2 shows the total mol% of the monomer and the number of moles of styrene monomer / (sum of moles of styrene monomer and moles of benzyl (meth) acrylate monomer). .
表１ 各共重合体の単量体組成 Table 1 Monomer composition of each copolymer
注）表１中のＳｔはスチレン、ＢｚＭＡはメタクリル酸ベンジル、ＢＭＡはメタクリル酸ブチル、ＢＡはアクリル酸ブチル、ＨＥＭＡはメタクリル酸２−ヒドロキシエチル、ＭＡＡはメタクリル酸、ＳｔｅａｒｙｌＭＡはメタクリル酸ステアリルを意味する。数字は、質量換算で全単量体を１００部とした時の各単量体の部数を表している。 Note) St in Table 1 is styrene, BzMA is benzyl methacrylate, BMA is butyl methacrylate, BA is butyl acrylate, HEMA is 2-hydroxyethyl methacrylate, MAA is methacrylic acid, and Stearyl MA is stearyl methacrylate. . The numbers represent the number of parts of each monomer when the total monomer is 100 parts in terms of mass.
表２ 各共重合体における特性パラメータ Table 2 Characteristic parameters for each copolymer
尚、表２中、Ｓｔ＋ＢｚＭＡは、共重合体に占めるスチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル％を意味し、Ｓｔ／Ｓｔ＋ＢｚＭＡは、スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル数に対するスチレン系単量体のモル数（％）を意味する。 In Table 2, St + BzMA means the total mol% of the styrene monomer and benzyl (meth) acrylate monomer in the copolymer, and St / St + BzMA is the styrene monomer. It means the number of moles (%) of styrene monomer relative to the total number of moles of methacrylic acid benzyl monomer.
以下、実施例にて本発明を詳細に説明するが、これらの実施例は本発明を具体的に説明するものであり、実施の態様がこれにより限定されるものではない。 EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, these Examples demonstrate this invention concretely and an aspect is not limited by this.
冷却用ジャケットを備えた混合槽に、合成例１で得た共重合体（Ｂ−１）、２０％水酸化ナトリウム水溶液、水及びＦａｓｔｏｇｅｎ（登録商標） Ｓｕｐｅｒ Ｍａｇｅｎｔａ ＲＹ〔大日本インキ化学工業（株）製Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｒｅｄ １２２〕８５０部、顔料誘導体であるフタルイミドメチル化−３，１０−ジクロロキナクリドン〔平均フタルイミドメチル基数１．４、大日本インキ化学工業（株）製〕５０部、顔料誘導体である３，１０−ジクロロキナクリドンスルホン酸ナトリウム〔大日本インキ化学工業（株）製〕のスラリー１２５０部（固形分換算で１００部）、メチルエチルケトン３００部、水を仕込み、攪拌、混合した。ここでそれぞれの仕込量は、キナクリドン顔料（顔料誘導体込みの量）が１，０００部、共重合体はキナクリドン顔料（顔料誘導体込みの量）に対して不揮発分で２０％の比率となる量、２０％水酸化ナトリウム水溶液はスチレン−アクリル系共重合体の酸価が１００％中和される量、水は混合液の不揮発分を３０％とするのに必要な量である。 In a mixing tank equipped with a cooling jacket, the copolymer (B-1) obtained in Synthesis Example 1, 20% aqueous sodium hydroxide solution, water and Fastogen (registered trademark) Super Magenta RY [Dainippon Ink Chemical Co., Ltd. C.) I. Pigment Red 122] 850 parts, pigment derivative phthalimidomethylated-3,10-dichloroquinacridone [average phthalimidomethyl group number 1.4, manufactured by Dainippon Ink & Chemicals, Inc.] 50 parts, pigment derivative 3,10 -1250 parts of slurry of sodium dichloroquinacridone sulfonate [manufactured by Dainippon Ink and Chemicals, Ltd.] (100 parts in terms of solid content), 300 parts of methyl ethyl ketone, and water were added, stirred and mixed. Here, the amount of each charged is 1,000 parts of quinacridone pigment (amount including pigment derivative), and the copolymer is an amount that has a non-volatile content ratio of 20% with respect to the quinacridone pigment (amount including pigment derivative), The 20% sodium hydroxide aqueous solution is an amount by which the acid value of the styrene-acrylic copolymer is neutralized by 100%, and water is an amount necessary to make the non-volatile content of the mixed solution 30%.
混合液を直径０．３ｍｍのジルコニアビーズを充填した分散装置〔ＳＣミル ＳＣ１００／３２型、三井鉱山（株）製〕に通し、循環方式により４時間分散した。分散装置の回転数は２７００回転／分とし、冷却用ジャケットには冷水を通して分散液温度が４０℃以下に保たれる様にした。
分散終了後、混合槽より分散原液を抜き採り、次いで水１０，０００部で混合槽及び分散装置流路を洗浄し、分散原液と合わせて希釈分散液を得た。希釈分散液をガラス製蒸留装置に入れ、メチルエチルケトンの全量と水の一部を常圧蒸留で除いた。
The mixed solution was passed through a dispersing device (SC mill SC100 / 32 type, manufactured by Mitsui Mining Co., Ltd.) filled with zirconia beads having a diameter of 0.3 mm, and dispersed for 4 hours by a circulation method. The number of revolutions of the dispersing device was 2700 rpm, and the temperature of the dispersion liquid was kept at 40 ° C. or less through the cooling jacket through cold water.
After the dispersion, the dispersion stock solution was extracted from the mixing tank, and then the mixing tank and the dispersion device flow path were washed with 10,000 parts of water, and the diluted dispersion liquid was obtained together with the dispersion stock solution. The diluted dispersion was put into a glass distillation apparatus, and the whole amount of methyl ethyl ketone and a part of water were removed by atmospheric distillation.
メチルエチルケトンの除かれた分散液を冷却し、その後、攪拌しながら１０％塩酸を滴下してｐＨ４．５に調整したのち、固形分をヌッチェ式濾過装置で濾過、水洗した。ケーキを容器に採り、スチレン−アクリル系共重合体の酸価が８５％中和される量の２０％水酸化カリウム水溶液と水を加え、分散攪拌機〔ＴＫホモディスパ２０型、特殊機化工業（株）製〕にて再度分散した。 The dispersion from which methyl ethyl ketone was removed was cooled, and then 10% hydrochloric acid was added dropwise with stirring to adjust the pH to 4.5, and then the solid content was filtered with a Nutsche filter and washed with water. Take the cake in a container, add 20% potassium hydroxide aqueous solution and water in such an amount that the acid value of the styrene-acrylic copolymer is neutralized by 85%, and add a dispersion stirrer [TK Homodispa Model 20, Special Machine Industries Co., Ltd. The product was dispersed again.
この分散液に、純水を加えて不揮発分２３％に調整した。この分散液を、遠心分離機〔５０Ａ−ＩＶ型、（株）佐久間製作所〕にて６０００Ｇ、３０分間かけて粗大粒子を除去したのち、純水を加えて不揮発分を調整し、不揮発分２０％のマゼンタ色水性顔料分散体を得た。この水性顔料分散体の分散粒子は、顔料が共重合体により被覆された複合粒子であった。 To this dispersion, pure water was added to adjust the non-volatile content to 23%. After removing the coarse particles from this dispersion with a centrifugal separator [50A-IV type, Sakuma Seisakusho Co., Ltd.] over 6000 G for 30 minutes, pure water was added to adjust the nonvolatile content, and the nonvolatile content was 20%. A magenta aqueous pigment dispersion was obtained. The dispersed particles of this aqueous pigment dispersion were composite particles in which the pigment was coated with a copolymer.
得られたマゼンタ色水性顔料分散体のｐＨは９．４２、不揮発分２０．０％、平均分散粒径（メディアン径）は１３６．９ｎｍであった。粘度は６．４０ ｍＰａ／ｓであった。この分散体は、ガラス容器中６０℃１０日間保存しても沈降物が全くなく、分散粒子の分散安定性には優れていた。 The obtained magenta color aqueous pigment dispersion had a pH of 9.42, a nonvolatile content of 20.0%, and an average dispersed particle size (median diameter) of 136.9 nm. The viscosity was 6.40 mPa / s. Even when this dispersion was stored in a glass container at 60 ° C. for 10 days, there was no sediment, and the dispersion stability of the dispersed particles was excellent.
（ピエゾ方式インクジェットプリンタ用水性顔料記録液の適性評価）
特開平７−２２８８０８号公報記載の実施例１を参考にしてピエゾ方式インクジェットプリンタ用インクを調製した。インク組成を以下に示す。本インクを用いてインクジェットプリンターで幾つかの被記録媒体にベタ印字し、印字試験として、着色画像濃度（発色性）を測定した。
(Evaluation of suitability of aqueous pigment recording liquid for piezo inkjet printers)
An ink for a piezo ink jet printer was prepared with reference to Example 1 described in JP-A-7-228808. The ink composition is shown below. Using this ink, solid printing was performed on several recording media using an ink jet printer, and the color image density (coloring property) was measured as a printing test.
水性顔料分散体 ３６ 部
トリエチレングリコールモノブチルエーテル １０ 部
ジエチレングリコール １５ 部
サーフィノール４６５（エアプロダクツ社製） ０．８部
水 ３８．２部
Aqueous pigment dispersion 36 parts triethylene glycol monobutyl ether 10 parts diethylene glycol 15 parts Surfynol 465 (manufactured by Air Products) 0.8 part water 38.2 parts
被記録媒体としては普通紙を選択し、Ｃａｎｏｎ（株）製Ｃａｎｏｎ ＰＢペーパー、Ｘｅｒｏｘ社製Ｘｅｒｏｘ４０２４、Ｈａｍｍｅｒｍｉｌｌ社製ＣｏｐｙＰｌｕｓの３種類を使用した。 Plain paper was selected as a recording medium, and three types of Canon PB paper manufactured by Canon Inc., Xerox 4024 manufactured by Xerox, and CopyPlus manufactured by Hammermill were used.
着色画像濃度は、グレタグマクベス社製ＧＲＥＴＡＧ（登録商標） Ｄ１９６を使用し、単一サンプルについて着色画像濃度を５点につき測定しそれらを平均した値である。この平均値を測定した結果として後記する表３に普通紙発色としてまとめた。この数字は、大きいほど発色性に優れていることを意味する。尚、Ｃａｎｏｎ（株）製Ｃａｎｏｎ ＰＢペーパーについて同一ロット製品の５枚について印字を行い、５サンプルについて単一サンプル当たり前記と同様に各々着色画像濃度を５点につき測定して平均値を求めてみたが、前記単一サンプルについて５点測定した場合とほぼ同様な結果となったため、いずれの普通紙においても単一サンプルについて着色画像濃度を５点につき測定しそれらを平均する様にした。このインクは、ガラス容器中６０℃１０日間保存しても沈降物が全くなく、分散粒子の分散安定性には優れていた。ルーペ（５０倍）にて普通紙のベタ印字部分を目視観察しても、印字表面にひび割れは観察されなかった。 The color image density is a value obtained by measuring the color image density of 5 points on a single sample using GRETAG (registered trademark) D196 manufactured by Gretag Macbeth and averaging them. As a result of measuring this average value, it was summarized as color development on plain paper in Table 3 to be described later. The larger the number, the better the color developability. For Canon PB paper manufactured by Canon Co., Ltd., printing was performed on 5 sheets of the same lot product, and for each of the 5 samples, the color image density was measured per 5 points in the same manner as described above, and the average value was obtained. However, since the result was almost the same as the case of measuring 5 points for the single sample, the color image density was measured for 5 points for a single sample in any plain paper and averaged. Even when this ink was stored in a glass container at 60 ° C. for 10 days, there was no sediment, and the dispersion stability of the dispersed particles was excellent. Even when the solid print portion of plain paper was visually observed with a magnifying glass (50 times), no cracks were observed on the print surface.
共重合体を（Ｂ−１）から（Ｂ−２）に変更した以外は実施例１と同様の操作でマゼンタ色水性顔料分散体を得た。この分散体は、実施例１と同様に、分散粒子の分散安定性には優れていた。得られた分散体を実施例1と同様の方法でインクを調製し、印字試験した。結果は表３にまとめた。このインクは、実施例１と同様に、分散粒子の分散安定性には優れていた。ルーペ観察でも、印字表面にひび割れは観察されなかった。 A magenta aqueous pigment dispersion was obtained in the same manner as in Example 1 except that the copolymer was changed from (B-1) to (B-2). As in Example 1, this dispersion was excellent in dispersion stability of the dispersed particles. An ink was prepared from the obtained dispersion in the same manner as in Example 1, and a printing test was conducted. The results are summarized in Table 3. As in Example 1, this ink was excellent in the dispersion stability of the dispersed particles. Even with the magnifying glass, no cracks were observed on the printed surface.
共重合体を（Ｂ−１）から（Ｂ−３）に変更した以外は実施例１と同様の操作でマゼンタ色水性顔料分散体を得た。この分散体は、実施例１と同様に、分散粒子の分散安定性には優れていた。得られた分散体を実施例1と同様の方法でインクを調製し、印字試験した。結果は表３にまとめた。このインクは、実施例１と同様に、分散粒子の分散安定性には優れていた。ルーペ観察でも、印字表面にひび割れは観察されなかった。 A magenta aqueous pigment dispersion was obtained in the same manner as in Example 1 except that the copolymer was changed from (B-1) to (B-3). As in Example 1, this dispersion was excellent in dispersion stability of the dispersed particles. An ink was prepared from the obtained dispersion in the same manner as in Example 1, and a printing test was conducted. The results are summarized in Table 3. As in Example 1, this ink was excellent in the dispersion stability of the dispersed particles. Even with the magnifying glass, no cracks were observed on the printed surface.
共重合体を（Ｂ−１）から（Ｂ−４）に変更した以外は実施例１と同様の操作でマゼンタ色水性顔料分散体を得た。この分散体は、実施例１と同様に、分散粒子の分散安定性には優れていた。得られた分散体を実施例1と同様の方法でインクを調製し、印字試験した。結果は表３にまとめた。このインクは、実施例１と同様に、分散粒子の分散安定性には優れていた。ルーペ観察でも、印字表面にひび割れは観察されなかった。 A magenta aqueous pigment dispersion was obtained in the same manner as in Example 1 except that the copolymer was changed from (B-1) to (B-4). As in Example 1, this dispersion was excellent in dispersion stability of the dispersed particles. An ink was prepared from the obtained dispersion in the same manner as in Example 1, and a printing test was conducted. The results are summarized in Table 3. As in Example 1, this ink was excellent in the dispersion stability of the dispersed particles. Even with the magnifying glass, no cracks were observed on the printed surface.
顔料をＦａｓｔｏｇｅｎ（登録商標）Ｓｕｐｅｒ Ｍａｇｅｎｔａ ＲY〔大日本インキ化学工業（株）製Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｒｅｄ １２２〕からＦａｓｔｏｇｅｎ（登録商標） Ｍａｇｅｎｔａ ＲＴＳ〔日本インキ化学工業（株）製Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｒｅｄ １２２〕に、共重合体を（Ｂ−１）から（Ｂ−５）に変更した以外は実施例１と同様の操作でマゼンタ色水性顔料分散体を得た。 The pigment is Fastogen (registered trademark) Super Magenta RY [C. I. Pigment Red 122] to Fastogen (registered trademark) Magenta RTS [manufactured by Nippon Ink Chemical Co., Ltd.] I. Pigment Red 122], a magenta aqueous pigment dispersion was obtained in the same manner as in Example 1, except that the copolymer was changed from (B-1) to (B-5).
得られたマゼンタ色水性顔料分散体のｐＨは９．２４、不揮発分２０．２％、平均分散粒径（メディアン径）は１５５．７ｎｍであった。粘度は５．８０ｍＰａ／ｓであった。この分散体は、実施例１の分散体と同様に、分散粒子の分散安定性には優れていた。 The obtained magenta aqueous pigment dispersion had a pH of 9.24, a non-volatile content of 20.2%, and an average dispersed particle size (median diameter) of 155.7 nm. The viscosity was 5.80 mPa / s. Similar to the dispersion of Example 1, this dispersion was excellent in the dispersion stability of the dispersed particles.
得られた分散体を実施例1と同様の方法でインクを調製し、印字試験した。結果は表２にまとめた。このインクは、実施例１と同様に、分散粒子の分散安定性には優れていた。ルーペ観察でも、印字表面にひび割れは観察されなかった。 An ink was prepared from the obtained dispersion in the same manner as in Example 1, and a printing test was conducted. The results are summarized in Table 2. As in Example 1, this ink was excellent in the dispersion stability of the dispersed particles. Even with the magnifying glass, no cracks were observed on the printed surface.
［比較例１］（特許文献２の実施例１に対応した比較例）
共重合体を（Ｂ−５）から（Ｂ−６）に変更した以外は実施例５と同様の操作でマゼンタ色水性顔料分散体を得た。
[Comparative Example 1] (Comparative example corresponding to Example 1 of Patent Document 2)
A magenta aqueous pigment dispersion was obtained in the same manner as in Example 5 except that the copolymer was changed from (B-5) to (B-6).
得られたマゼンタ色水性顔料分散体のｐＨは９．２４、不揮発分２０．２％、平均分散粒径（メディアン径）は１７５．５ｎｍであった。粘度は６．３８ｍＰａ／ｓであった。この分散体は、実施例１の分散体と同様に、分散粒子の分散安定性には優れていた。 The obtained magenta color aqueous pigment dispersion had a pH of 9.24, a non-volatile content of 20.2%, and an average dispersed particle size (median diameter) of 175.5 nm. The viscosity was 6.38 mPa / s. Similar to the dispersion of Example 1, this dispersion was excellent in the dispersion stability of the dispersed particles.
得られた分散体を実施例1と同様の方法でインクを調製し、印字試験した。結果は表３にまとめた。このインクは、実施例１と同様に、分散粒子の分散安定性には優れていた。ルーペ観察でも、印字表面にひび割れは観察されなかった。 An ink was prepared from the obtained dispersion in the same manner as in Example 1, and a printing test was conducted. The results are summarized in Table 3. As in Example 1, this ink was excellent in the dispersion stability of the dispersed particles. Even with the magnifying glass, no cracks were observed on the printed surface.
［比較例２］
共重合体を（Ｂ−１）から（Ｂ−７）に変更した以外は実施例１と同様の操作でマゼンタ色水性顔料分散体を得た。
[Comparative Example 2]
A magenta aqueous pigment dispersion was obtained in the same manner as in Example 1 except that the copolymer was changed from (B-1) to (B-7).
得られたマゼンタ色水性顔料分散体のｐＨは９．４３、不揮発分１９．７％、平均分散粒径（メディアン径）は１３９．０ｎｍであった。粘度は５．６８ｍＰａ／ｓであった。この分散体は、実施例１の分散体と同様に、分散粒子の分散安定性には優れていた。 The obtained magenta color aqueous pigment dispersion had a pH of 9.43, a nonvolatile content of 19.7%, and an average dispersed particle size (median diameter) of 139.0 nm. The viscosity was 5.68 mPa / s. Similar to the dispersion of Example 1, this dispersion was excellent in the dispersion stability of the dispersed particles.
得られた分散体を実施例1と同様の方法でインクを調製し、印字試験した。結果は表３にまとめた。このインクは、実施例１と同様に、分散粒子の分散安定性には優れていた。また、ルーペ観察では、印字表面にひび割れが観察された。 An ink was prepared from the obtained dispersion in the same manner as in Example 1, and a printing test was conducted. The results are summarized in Table 3. As in Example 1, this ink was excellent in the dispersion stability of the dispersed particles. In the magnifying glass, cracks were observed on the print surface.
［比較例３］
共重合体を（Ｂ−７）から（Ｂ−８）に変更した以外は実施例５と同様の操作でマゼンタ色水性顔料分散体を得た。
[Comparative Example 3]
A magenta aqueous pigment dispersion was obtained in the same manner as in Example 5 except that the copolymer was changed from (B-7) to (B-8).
得られたマゼンタ色水性顔料分散体のｐＨは９．２０、不揮発分１９．４％、平均分散粒径（メディアン径）は１２５．０ｎｍであった。粘度は６．７０ｍＰａ／ｓであった。この分散体は、実施例１の分散体と同様に、分散粒子の分散安定性には優れていた。 The obtained magenta color aqueous pigment dispersion had a pH of 9.20, a nonvolatile content of 19.4%, and an average dispersed particle size (median diameter) of 125.0 nm. The viscosity was 6.70 mPa / s. Similar to the dispersion of Example 1, this dispersion was excellent in the dispersion stability of the dispersed particles.
得られた分散体を実施例1と同様の方法でインクを調製し、印字試験した。結果は表３にまとめた。このインクは、実施例１と同様に、分散粒子の分散安定性には優れていた。ルーペ観察でも、印字表面にひび割れは観察されなかった。 An ink was prepared from the obtained dispersion in the same manner as in Example 1, and a printing test was conducted. The results are summarized in Table 3. As in Example 1, this ink was excellent in the dispersion stability of the dispersed particles. Even with the magnifying glass, no cracks were observed on the printed surface.
［比較例４］（特許文献２の比較例１に対応した比較例）
共重合体を（Ｂ−７）から（Ｂ−９）に変更した以外は実施例５と同様の操作でマゼンタ色水性顔料分散体を得た。この分散体は、実施例１の分散体と同様に、分散粒子の分散安定性には優れていた。得られた分散体を実施例1と同様の方法でインクを調製し、印字試験した。結果は表３にまとめた。このインクは、実施例１と同様に、分散粒子の分散安定性には優れていた。ルーペ観察でも、印字表面にひび割れは観察されなかった。
[Comparative Example 4] (Comparative Example corresponding to Comparative Example 1 of Patent Document 2)
A magenta aqueous pigment dispersion was obtained in the same manner as in Example 5 except that the copolymer was changed from (B-7) to (B-9). Similar to the dispersion of Example 1, this dispersion was excellent in the dispersion stability of the dispersed particles. An ink was prepared from the obtained dispersion in the same manner as in Example 1, and a printing test was conducted. The results are summarized in Table 3. As in Example 1, this ink was excellent in the dispersion stability of the dispersed particles. Even with the magnifying glass, no cracks were observed on the printed surface.
［比較例５］（特許文献２の比較例４に対応した比較例）
共重合体を（Ｂ−７）から（Ｂ−１０）に変更した以外は実施例５と同様の操作でマゼンタ色水性顔料分散体を得た。この分散体は、実施例１の分散体と同様に、分散粒子の分散安定性には優れていた。得られた分散体を実施例1と同様の方法でインクを調製し、印字試験した。結果は表３にまとめた。このインクは、実施例１と同様に、分散粒子の分散安定性には優れていた。ルーペ観察でも、印字表面にひび割れは観察されなかった。
[Comparative Example 5] (Comparative Example corresponding to Comparative Example 4 of Patent Document 2)
A magenta aqueous pigment dispersion was obtained in the same manner as in Example 5 except that the copolymer was changed from (B-7) to (B-10). Similar to the dispersion of Example 1, this dispersion was excellent in the dispersion stability of the dispersed particles. An ink was prepared from the obtained dispersion in the same manner as in Example 1, and a printing test was conducted. The results are summarized in Table 3. As in Example 1, this ink was excellent in the dispersion stability of the dispersed particles. Even with the magnifying glass, no cracks were observed on the printed surface.
［比較例６］
共重合体を（Ｂ−７）から（Ｂ−１１）に変更した以外は実施例５と同様の操作でマゼンタ色水性顔料分散体を得た。この分散体は、実施例１の分散体と同様に、分散粒子の分散安定性には優れていた。得られた分散体を実施例1と同様の方法でインクを調製し、印字試験した。結果は表３にまとめた。このインクは、実施例１と同様に、分散粒子の分散安定性には優れていた。ルーペ観察でも、印字表面にひび割れは観察されなかった。
[Comparative Example 6]
A magenta aqueous pigment dispersion was obtained in the same manner as in Example 5 except that the copolymer was changed from (B-7) to (B-11). Similar to the dispersion of Example 1, this dispersion was excellent in the dispersion stability of the dispersed particles. An ink was prepared from the obtained dispersion in the same manner as in Example 1, and a printing test was conducted. The results are summarized in Table 3. As in Example 1, this ink was excellent in the dispersion stability of the dispersed particles. Even with the magnifying glass, no cracks were observed on the printed surface.
表３ マゼンタ印字評価結果 Table 3 Magenta print evaluation results
注）表中の印字状態とは、印字表面のルーペ観察の結果を意味する。 Note) The printed status in the table means the result of magnifying the printed surface.
比較例のインクジェット記録用水性インクは、用いたスチレン−アクリル系共重合体が、本発明で規定する３つの指標のうち少なくとも一つが規定する数値範囲から逸脱するために、被記録媒体上の着色画像濃度が低いということがわかる。 Since the styrene-acrylic copolymer used in the comparative ink jet recording water-based ink deviates from a numerical range defined by at least one of the three indices defined in the present invention, coloring on the recording medium It can be seen that the image density is low.
前記実施例４で得られた水性顔料分散体１００部（顔料分１６．７％）に、ハイドラン（登録商標）ＡＰ−４０Ｆ（大日本インキ化学工業（株）製水性のポリエステル系ポリウレタンの水分散体、平均分散粒径（メディアン径）８ｎｍ、不揮発分２３％）４．４部を添加して、均一となる様に攪拌した。尚、このハイドラン（登録商標）ＡＰ−４０Ｆの添加量は、水性顔料分散体中の顔料１００部当たり、樹脂分にして６部に相当している。
ポリウレタンを含有しない水性顔料分散体に代えて、こうして得られたポリウレタンを含有する水性顔料分散体の同量を用いる以外は実施例４と同様にして、インクジェット記録用水性インクを調製した。
こうして得られたインクジェット記録用水性インクで、実施例１と同様にして、Ｃａｎｏｎ（株）製フォト光沢フィルムＨＧ２０１にベタ印字を行い、印字から一定時間毎に指で擦って色の滲み方を観察し、耐擦過性を評価した。対比のために、実施例４のポリウレタンを含有しない水性顔料分散体から調製したインクジェット記録用水性インクでも同様に耐擦過性を評価し、これらの結果を合わせて表４に示した。
To 100 parts of the aqueous pigment dispersion obtained in Example 4 (pigment content: 16.7%), water dispersion of Hydran (registered trademark) AP-40F (water-based polyester polyurethane manufactured by Dainippon Ink & Chemicals, Inc.) And 4.4 parts of an average dispersion particle diameter (median diameter) of 8 nm, non-volatile content of 23%) were added and stirred to be uniform. The amount of Hydran (registered trademark) AP-40F added corresponds to 6 parts of resin per 100 parts of pigment in the aqueous pigment dispersion.
An aqueous ink for inkjet recording was prepared in the same manner as in Example 4 except that the same amount of the aqueous pigment dispersion containing polyurethane thus obtained was used instead of the aqueous pigment dispersion not containing polyurethane.
With the water-based ink for ink jet recording thus obtained, solid printing was performed on the photo glossy film HG201 made by Canon Co., Ltd. in the same manner as in Example 1, and the color bleeding was observed by rubbing with a finger at regular intervals from the printing. Then, scratch resistance was evaluated. For comparison, the water resistance for ink jet recording prepared from the aqueous pigment dispersion containing no polyurethane of Example 4 was similarly evaluated for scratch resistance, and the results are shown in Table 4.
表４ 耐擦過性の評価 Table 4 Evaluation of scratch resistance
注）表中の耐擦過性の評価区分は次の通りである。
Ａ：滲み無し、Ｂ：滲み無し、指に色が付く、Ｃ：うっすらと滲む、Ｄ：滲む、
Ｅ：激しく滲む
Note) The evaluation categories of scratch resistance in the table are as follows.
A: No blur, B: No blur, finger is colored, C: Slightly blur, D: Smudge
E: Severe bleeding
実施例６のポリウレタンを含むインクジェット記録用水性インクは、実施例４のポリウレタンを含まないインクジェット記録用水性インクに比べて、印字直後の耐擦過性に優れている。また、実施例４のポリウレタンを含まないインクジェット記録用水性インクは、印字から長時間経過しないと耐擦過性が向上しないが、実施例６のポリウレタンを含むインクジェット記録用水性インクは、印字から短時間経過するだけで耐擦過性が向上することがわかる。
The water-based ink for inkjet recording containing the polyurethane of Example 6 is superior to the water-based ink for inkjet recording not containing the polyurethane of Example 4 in scratch resistance immediately after printing. Further, the water-based ink for ink-jet recording containing no polyurethane of Example 4 does not improve the scratch resistance until a long time has elapsed since printing, but the water-based ink for ink-jet recording containing polyurethane of Example 6 is short after printing. It can be seen that the scratch resistance is improved only by passing.
Claims (6)
スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計が４０〜８０モル％であり、
スチレン系単量体と（メタ）アクリル酸ベンジル系単量体との合計モル数に対するスチレン系単量体のモル数が４０〜９０％であり、かつ、酸価８５〜１３５のスチレン−アクリル系共重合体を用いることを特徴とする水性顔料分散体。 A pigment (A), a styrene-acrylic copolymer (B) obtained by polymerizing a styrene monomer, a benzyl (meth) acrylate monomer and (meth) acrylic acid, and a basic substance (C In the water-based pigment dispersion for inkjet recording water-containing inks, the styrene-acrylic copolymer (B) contains polymerized units of benzyl (meth) acrylate monomers,
The total of the styrene monomer and the benzyl (meth) acrylate monomer is 40 to 80 mol%,
Styrene-acrylic system having 40 to 90% of the number of moles of styrene-based monomer with respect to the total number of moles of styrene-based monomer and benzyl (meth) acrylate and having an acid value of 85 to 135 A water-based pigment dispersion characterized by using a copolymer.
A water-based ink for inkjet recording, comprising the water-based pigment dispersion according to any one of claims 1 to 5.
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| JP3813952B2 (en) * | 2003-07-22 | 2006-08-23 | 花王株式会社 | Water-based ink |
| US7291659B2 (en) * | 2004-08-06 | 2007-11-06 | Kao Corporation | Water-based inks for ink-jet printing |
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| JPH10292141A (en) * | 1997-04-16 | 1998-11-04 | Seiko Epson Corp | Ink for ink jet recording, and device for ink jet recording |
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