JPH07173424A - Low-foaming water-base ink composition - Google Patents

Abstract

PURPOSE:To obtain a compsn. which is excellent in antifoaming properties by compounding a colorant, a specific binder, and a specific antifoaming compsn. as the main components. CONSTITUTION:This compsn. contains a colorant, a binder sol. or emulsifiable in water, and a specified amt. of a specific silicone-based antifoaming compsn. as the main components. The antifoaming compsn. comprises specified amts. of an organopolysiloxane of the formula: GaR<1>bSi04-a-b-/2 [wherein G is- R20(R30)pQ (wherein R<2> is a 1-10C divalent hydrocarbon group; R<3> is an ethylene or propylene group; Q is H, 1-18C alkyl, acetyl, or isocyanate; and p is a natural number); R<1> is a 1-18C monovalent hydrocarbon group; and a is 0.005-0.5 and b is 1.4-2.195 provided a+b is 1.9-2.2], a dimethylpolysiloxane having a specified viscosity, a fine silica powder having a specified specific surface area, and an org.-solvent-sol. silicone resin which consists of structural units selected from the group consisting of R<4>3Si01/2, Si02, R<4>2Si0, and R4Si03/2 (wherein R' is a 1-6C monovalent hydrocarbon group) and linked to each other in a specified manner.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a low-foaming water-based ink composition, and in particular, it is excellent in foam-suppressing property, and therefore can maintain low foaming property even under severe conditions under high temperature or high shearing force. The present invention relates to a low-foaming water-based ink composition capable of

[0002]

2. Description of the Related Art Regarding aqueous printing ink compositions, it is an important factor for printability that they are suitable for printing operations in the processes of printing, drying and post-processing by a printing machine. In the printing process, high shearing force is constantly applied by rolls rotating at high speed, so ink is overflowing from the supply tank due to foaming based on the water-based ink composition, and problems such as uneven ink supply occur when workability is significantly impaired. There are many. Therefore, a method has been adopted in which an antifoaming agent is added to this type of ink composition to prevent foaming during the printing process. To this end, dimethylpolysiloxane is dispersed in water using a surfactant. Emulsion type defoamers are widely used.

However, when the liquid to be treated is at a high temperature, this product breaks the emulsion when high shearing force is applied to lower the defoaming effect and sometimes promotes foaming, and during long-term storage. The emulsion is separated, and cissing occurs due to the water repellency of the dimethylpolysiloxane after separation, which has the disadvantage of deteriorating the printing quality.Therefore, this is an organopolysiloxane modified with a polyoxyalkylene group. It has been proposed (see US Pat. No. 3233986) to use the diorganosiloxane represented by such a modified siloxane and dimethylpolysiloxane because of its disadvantage of having a small defoaming effect. Attempts have also been made to improve the defoaming effect by using polysiloxane in combination (see JP-A-53-34854). However, when added to a water-based ink or the like, the organic substances in the system and dimethylpolysiloxane have a poor affinity, so that they eventually separate and cause cissing.

[0004]

Therefore, in this low-foaming water-based ink composition, a hydrocarbon group having 4 to 18 carbon atoms is introduced into dimethylpolysiloxane to have an affinity with the resin component in the water-based ink. Attempts have been made to improve the dispersion and maintain good dispersion in water, and a self-emulsifying defoaming agent that actually combines this hydrocarbon-modified siloxane and polyoxyalkylene-modified siloxane has also been proposed (JP-A-54). -
However, this has a drawback in that the defoaming durability is poor although it is improved in terms of cissing. Therefore, the inventors of the present invention have for the purpose of improving defoaming persistence and the like a defoaming agent comprising a polyoxyalkylene-modified siloxane having a limited structure, dimethylpolysiloxane, finely divided silica and a surfactant. Proposed mixed water-based ink composition (see Japanese Patent Publication No. 1-30872)
However, since the defoaming durability is insufficient, further improvement of the characteristics is required.

[0005]

The present invention relates to a low-foaming water-based ink composition which solves the above disadvantages and problems, and it relates to (A) a colorant, (B) a dissolved state in water or Binder resin in emulsion state,
(C) Silicone-based defoaming agent composition comprising the following a) to d), a) General formula (1) G _a R ¹ _b SiO _{4 -ab / 2} ... (1) [1] here G is the formula ^{(2) -R 2 -O- (R} 3 -O) p -Q ······ (2) ( this R ² is a divalent hydrocarbon group having 1 to 10 carbon atoms, R ³ is an ethylene group and / or a propylene group, Q is a hydrogen atom or a monovalent organic group selected from an alkyl group having 1 to 8 carbon atoms, an acetyl group and an isocyanic acid group, and p is a natural number). An alkylene group, R ¹ is one or more monovalent hydrocarbon groups having 1 to 18 carbon atoms, and a and b are 0.005 ≦ a ≦ 0.5, 1.4 ≦ b ≦ 2.195 and 1.9 ≦ a, respectively.
+ B ≦ 2.2] 100 parts by weight of polyoxyalkylene group-containing organopolysiloxane, b) 2 to 200 parts by weight of dimethylpolysiloxane having a viscosity at 25 ° C. of 100 to 1,000,000 cS, and c) specific surface area of 50 m ² / g
0.1 to 40 parts by weight of finely divided silica, d) Formula R ⁴ ₃ SiO
_A unit selected from _1/2 unit, SiO ₂ unit, R ⁴ ₂ SiO unit, R ⁴ SiO _3/2 unit (where R ⁴ is a monovalent hydrocarbon group having 1 to 6 carbon atoms), and all of these units. Of the constitutional units, the total amount of R ⁴ ₃ SiO _1/2 units and SiO ₂ units is 80 mol% or more, and the molar ratio of R ⁴ ₃ SiO _1/2 units / SiO ₂ units is in the range of 0.5 to 1.5. Organic solvent-soluble silicone resin 0.05 to 60 parts by weight as a main component, and component (C) is 0.01 to 10% by weight in the entire composition.
It is characterized by containing.

That is, the present inventors have conducted various studies to develop an aqueous ink composition which solves the above-mentioned disadvantages and exhibits a low foaming property even at high temperature or under high shear. As a result, an aqueous ink composition The defoaming agent to be added to is composed of a polyoxyalkylene group-containing organopolysiloxane, dimethylpolysiloxane and finely divided silica, R ⁴ ₃ SiO _1/2 unit, SiO ₂ unit, R ⁴ ₃ SiO unit and R ⁴ Si
An organic solvent-soluble silicone resin consisting of O _3/2 units is added, and the total amount of R ⁴ ₃ SiO _1/2 units and SiO ₂ units among the constituent units of this silicone resin is 80 mol%, The molar ratio of this R ⁴ ₃ SiO _1/2 unit / SiO ₂ unit is 0.5 to
It has been found that, when the range is 1.5, the defoaming agent composition exhibits excellent defoaming effect and durability without breaking the emulsion even under high temperature and high shear conditions. Therefore, the water-based ink composition to which it is added exhibits excellent printability, and since this composition is easily obtained by simple mixing of each of these components, it is economical. It was confirmed that the desired low-foaming water-based ink composition was obtained safely, and the type of each component used here,
The present invention has been completed by conducting research on the compounding ratio and the like. This will be described in more detail below.

[0007]

As the colorant as the component (A) constituting the low foaming ink composition of the present invention, dyes, inorganic and organic pigments generally used in aqueous printing inks can be used. As this dye, azo dye, anthraquinone dye,
Indigo dye, phthalocyanine dye, carbonyl dye,
Examples of quinone imine dyes, methine dyes, quinoline dyes, nitro dyes, and the like can be used as inorganic pigments such as titanium oxide, red iron oxide, antimony red, cadmium red, cadmium yellow, cobalt blue, navy blue, ultramarine blue, carbon black, graphite. Examples of such organic pigments include soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments and condensed polycyclic pigments.

Next, as the binder resin as the component (B) which constitutes this low-foaming aqueous ink composition,
Natural or processed resins such as starch, dextrin, glue, casein, shellac, arabic gum, rosin and rosin ester, cellulose derivatives such as methylcellulose and ethylcellulose, phenolic resins, maleic acid resins,
Modified maleic acid resin, styrene-maleic acid resin, styrene-maleic acid-acrylic resin, petroleum resin, vinyl resin, acrylic resin, polyamide resin, epoxy resin, alkyd resin, aqueous solution of synthetic resin such as polyvinyl alcohol, alkaline aqueous solution or emulsion. Can be used alone or as a mixture.

Next, as described above, the silicone-based defoaming agent composition (C) which constitutes the low-foaming water-based ink composition of the present invention is a) polyoxyalkylene group-containing organopolysiloxane, and b) dimethyl. Polysiloxane, c)
The fine powder silica, d) is composed of an organic solvent-soluble silicone resin, and these are required to be the following, respectively.

The polyoxyalkylene group-containing organopolysiloxane as the component (a) is represented by the general formula (1) G _a R ¹ _b SiO _{4 -ab / 2} (1) . G in the above general formula (1) is a polyoxyalkylene group represented by the general formula -R ² -O- (R ³ O) _p -Q (2), and R ² is methylene. Group, ethylene group, propylene group, butylene group,
C1-C10 such as hexene group, octene group, decene group
A divalent hydrocarbon group, R ³ is an ethylene group and / or a propylene group, Q is a hydrogen atom or a methyl group, an ethyl group,
A monovalent organic group selected from an alkyl group having 1 to 8 carbon atoms such as a propyl group, a butyl group, a hexyl group and an octyl group, an acetyl group and an isocyanic acid group, and p is a natural number.

R ¹ in the general formula (1) is a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group,
Hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, tetradecyl group, hexadecyl group,
Alkyl group such as octadecyl group, cycloalkyl group such as cyclohexyl group, alkenyl group such as vinyl group and allyl group, aryl group such as phenyl group and tolyl group, 2
One or two selected from aralkyl groups such as -phenylethyl group and 2-methyl-2-phenylethyl group
It is a monovalent hydrocarbon group having 1 to 8 or more carbon atoms, and from the viewpoint of defoaming property and economical efficiency, it is preferable that 80 mol% or more of all R ¹ groups are methyl groups. These a and b are 0.005 ≦ a ≦ 0.5 and 1.4 ≦ b ≦ 2.195, respectively.
1.9 ≦ a + b ≦ 2.2.

As the polyoxyalkylene group-containing organopolysiloxane, various ones can be used, from liquid at room temperature to paste-like one having a melting point at room temperature to about 80 ° C. When the viscosity or melt viscosity is lower than 10 cS, the obtained defoaming agent composition is easy to separate and has low stability.
When it is higher than 0 cS, it becomes difficult to disperse the resulting defoaming agent composition in the aqueous ink composition, resulting in poor workability, so that the viscosity may be 10 to 100,000 cS. Good, but the preferred range is 100-10,000 cS.

As the polyoxyalkylene group-containing organopolysiloxane, a commercially available polyether-modified silicone may be used. This is a conventionally known method, for example, an organopolysiloxane containing ≡SiH groups. In addition, a polyoxyalkylene compound having an unsaturated group such as a vinyl group or an allyl group at the terminal of the molecular chain can be easily obtained by addition reaction in the presence of a platinum catalyst. It should be noted that this is not limited to a silicone oil modified with a single polyoxyalkylene compound, but two or more polyoxyalkylene groups having different ethyleneoxy group / propyleneoxy group molar ratios or molecular weights of polyoxyalkylene groups. Silicone oils contained in the same molecule can be used, and two or more kinds of polyoxyalkylene-modified silicone oils having different structures can also be used.

Next, the dimethylpolysiloxane as the component (b) is a main component for imparting defoaming persistence to the composition of the present invention, which may be linear or branched. May have a trimethylsilyl group at the end,
Any substance blocked with a monohydroxydimethylsilyl group may be used. This viscosity should be as low as possible from the viewpoint of ease of dispersion and cissing prevention, but it is better from the viewpoint of maintaining defoaming property, so 100-1,000,00
The range may be 0 cS, but at least 1,000 cS or more from the viewpoint of compatibility with the polyoxyalkylene group-containing organopolysiloxane as the component (a) and affinity with the organic substance contained in the dispersion medium, From the viewpoint of dispersibility, it is preferably 100,000 cS or less. It should be noted that if the compounding ratio of the component (b) to the component (a) is too small, the defoaming performance will not be sufficiently exhibited, and if it is too large, the hydrophobicity will be strong and the dispersibility and stability will be poor, causing the cissing. 2) for 100 parts by weight of component a)
The amount is required to be 200 parts by weight, but it is preferably 5 to 100 parts by weight from the viewpoint of dispersibility and defoaming property.

The finely divided silica as the component (c) may be a known one, and either wet silica or dry silica can be used, and precipitated silica, silica xerogel, fumed silica and the surface thereof can be used. Examples thereof include silica treated with an organic silyl group. Specifically, Aerosil [trade name of Nippon Aerosil Co., Ltd.], Nipsil [trade name of Nihon Silica Co., Ltd.], Cabosil (trade name of Cabot Corporation of the United States) , Santocell (trade name, manufactured by Monsanto, USA), and the like.
It is required that the specific surface area by the ET method is 50 m ² / g or more, which is preferably 100 m ² / g.
The above is preferable. In addition, even if this mixing ratio is too large or too small, the defoaming performance is not sufficiently exhibited,
On the other hand, if the amount is too large, the system thickens and a handling problem occurs.
~ 40 parts by weight is required, but preferably 1
It is preferably in the range of up to 20 parts by weight.

Furthermore, organic solvent-soluble silicone resin as the two) component, defoaming persistence of the composition of the present invention is improved, but is intended to suppress the occurrence of cissing and oil spots which R ⁴ ₃ It is composed of a unit selected from SiO _1/2 unit, SiO ₂ unit, R ⁴ ₂ SiO unit, and R ⁴ SiO _3/2 unit. R ⁴ is one or more carbon atoms selected from an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group and a hexyl group, a cycloalkyl group such as a cyclohexyl group and a phenyl group. Is 1-6
Is a monovalent hydrocarbon group of 80 mol% of the total R ⁴ groups
The above is preferably a methyl group.

However, among these units R ⁴ ₃ SiO
_1/2 unit and SiO ₂ unit are indispensable units. If the total amount of these two units is less than 80 mol% of the total constitutional units, the defoaming durability will be poor, so this is above 80 mol%. It is essential that the amount of R ⁴ ₃ SiO _1/2 units / SiO ₂ units is not less than 90 mol%.
If it is less than 0.5, the dispersibility of the component (d) in the composition becomes poor, and if it exceeds 1.5, the defoaming persistence decreases.
Since cissing tends to occur, it is necessary to set this in the range of 0.5 to 1.5, but this preferable range is 0.7
~ 1.2.

If the mixing ratio of the component (d) to the component (a) is too large or too small with respect to 100 parts by weight of the component (a), the defoaming performance will not be sufficiently exhibited, and especially this will be too large. Since the system thickens and causes problems in working, it is necessary to set it to 0.05 to 60 parts by weight, and this preferable range is 0.5 to 30 parts by weight.

The defoaming agent composition as the component (C) which constitutes the low-foaming aqueous ink composition of the present invention has the above-mentioned a) to
(D) It can be obtained by uniformly mixing a predetermined amount of the components with a mixer such as a homomixer, but the order of mixing is not particularly limited, and it can be
D) The components may be mixed at once, or b) -d) components may be mixed and then the a) component may be added thereto and mixed. In this case, this may be 40-200 ° C as necessary. Alternatively, a wax, a plasticizer, a stabilizer, a dispersant, a filler, a solvent or the like may be added as an optional component to the low-foaming aqueous ink composition of the present invention.

A water-based ink composition can be obtained by uniformly mixing the above-mentioned colorant, binder resin and water. The content of each of these components is 0.1% by weight when the content of the colorant is a dye. If it is less than 0.5% by weight in the case of pigment, the color density necessary for the ink cannot be obtained, and if it exceeds 5% by weight in the case of dye and 60% by weight in the case of pigment, the dispersion stability of the dye or pigment decreases. It is necessary to set the range of 0.1 to 5% by weight for dyes and 0.5 to 60% by weight for pigments.

The content of the binder resin is 3
If it is less than 10% by weight, the ink viscosity becomes too low to obtain good printability, the ink film becomes brittle, and it is 30% by weight in the case of a binder resin which is in a dissolved state in water, and in the case of a binder resin in an emulsion state. If it exceeds 60% by weight, a large amount of ink will need to be diluted and color density will not be obtained, and it will cause poor fluidity. Therefore, 3 to 30% by weight of binder resin that is dissolved in water, emulsion state 3 to 60% by weight is required for the binder resin in.

The low-foaming water-based ink composition of the present invention comprises the above-mentioned coloring agent as component (A), binder resin as component (B), silicone antifoam composition as component (C), and necessary components. It can be obtained by uniformly kneading or kneading the other auxiliaries added in accordance with the above with a solvent and a diluent by a roll mill, a ball mill, an attritor, a sand mill, a dissolver, a homomixer or the like. In addition, (A) in the low foaming water-based ink composition of the present invention,
The blending amounts of the components (B) and (C) are slightly different depending on the other components of the water-based ink composition and the type of the defoaming agent composition, but generally, the defoaming agent composition is added to 100 parts by weight of the ink composition. 0.01 to 10 parts by weight, preferably 0.1 to 1 part by weight.

[0023]

EXAMPLES Next, examples of the present invention, production examples of the silicone antifoam composition used in Comparative Examples and Examples of the present invention, Comparative Examples will be given. Parts in the examples are parts by weight, Unless otherwise specified, the viscosity indicates the value measured at 25 ° C., and the defoaming test of this water-based ink composition, the defoaming test by a printing machine, and the cissing test were carried out by the following methods, respectively. The binder resin, water-soluble resin varnish, and silicone-based defoaming agent composition used here are produced by the following method. (Defoaming test) A silicone defoamer composition prepared in Examples and Comparative Examples was added to a water-based ink composition in a 1,000 ml tall beaker.
200 g of the water-based ink composition obtained by adding 0.3% by weight was weighed, and this was stirred with a low-viscosity homomixer at a rotational speed of 7,000 rpm to measure the foaming amount (foam height) at that time, Then, this was left in a constant temperature bath at 40 ° C. for 1 week, and the amount of foaming was measured again by the same method.

(Defoaming Test Using a Printing Machine) 0.3% by weight of the silicone-based defoaming agent compositions prepared in Examples and Comparative Examples were added to the aqueous ink composition to obtain a flexo ink. Printing was performed with a two-color printing machine and the state of bubbles generated on the surface of the ink bat was observed and evaluated as follows. ◎ ... No bubbles at all ○ ... Some bubbles remain at the corners of the ink vat △ ... The bubbles cover the surface of the ink vat × ... A lot of bubbles overflow from the ink vat and cannot be sucked up by the pump (Hajiki test) The water-based ink composition obtained by adding 0.3% by weight of the obtained silicone-based defoamer composition was spread on a water-repellent liner paper with a 0.15 mmφ Mayer bar, and the repellency after drying was observed. evaluated. ◎ ... same as blank (without defoaming agent added) ◯ ... slight cissing is present, but almost the same as blank ∆ ... A lot of cissing is present × ... innumerable cissing

(Production Example of Binder Resin) Resin Synthesis Example 1 A four-necked flask equipped with a stirrer, a cooling pipe and a nitrogen gas introduction pipe was charged with 600 parts of ethyl acetate and heated to 75 to 78 ° C. While introducing gas, a mixture of 249 parts of monobutyl maleate, 151 parts of styrene and 4 parts of ditertiary butyl peroxide as a reaction initiator was added thereto.
After dropwise addition over a period of time and random copolymerization for 2 hours while maintaining the same temperature, the solvent was evaporated under reduced pressure to obtain a styrene-maleic acid resin. Resin Synthesis Example 2 The same equipment as in Synthesis Example 1 was charged with 600 parts of ethyl acetate.
After heating to ~ 78 ° C, while introducing nitrogen gas, a mixture of 158 parts of monobutyl maleate, 161 parts of styrene, 81 parts of butyl acrylate and 4 parts of ditert-butyl peroxide as a reaction initiator was added thereto for 2 hours. Then, the mixture was dropped, and random copolymerization was performed for 2 hours while maintaining the same temperature, and then the solvent was evaporated under reduced pressure to obtain a styrene-maleic acid-acrylic resin.

(Preparation of Water-Soluble Resin Varnish) 400 parts of the styrene-maleic acid resin obtained in Synthesis Example 1 of water-based resin was crushed, and then stirred and mixed in 600 parts of water in which an equivalent amount of ammonia was dissolved. Dissolve by heating at ℃, solid content 40%, viscosity
A water-soluble resin varnish 1 of 20 poise (20 ° C.) was obtained. Also,
After crushing 400 parts of the styrene-maleic acid-acrylic resin obtained in Aqueous Resin Synthesis Example 2, the mixture was stirred and mixed in 600 parts of water in which an equivalent amount of ammonia was dissolved, and dissolved by heating at 80 ° C to obtain a solid content. A water-soluble resin varnish 2 having a viscosity of 18 poise (20 ° C.) of 40% was obtained.

(Production Examples 1 to 1 of silicone antifoam composition)
15) The following materials are used as the components a) to d), these are blended in the composition shown in Table 1, and after being heated to 60 ° C., uniformly mixed with a homomixer to defoam composition A P was prepared.

[0028]

[Table 1]

(Material used for preparation of defoaming agent composition) 1) Polyoxyalkylene group-containing organopolysiloxane A The average composition formula is G ¹ _0.1 (CH ₃ ) _2.0 SiO _0.95 [G ¹ = -C ₃ H ₆ O (C ₂ H ₄ O)
₂₅ (C ₃ H ₆ O) ₂₅ C ₄ H ₉ ] having a viscosity of 1,400 cS, 2) polyoxyalkylene group-containing organopolysiloxane B having an average composition formula of G ² _0.03 (C ₁₀ H ₂₁ ) _0.03 ( CH ₃ ) _1.98 SiO _0.98 [G ²
= -C ₃ H ₆ O (C ₂ H ₄ O) ₆ (C ₃ H ₆ O) ₂₄ H] has a viscosity of 1,100 cS
3) Polyoxyalkylene group-containing organopolysiloxane C having an average composition formula of G ³ _0.08 G ⁴ _0.02 (C ₈ H ₁₇ ) _0.03 (CH ₃ ) _1.93 SiO
_0.97 [G ³ = -C ₃ H ₆ O (C ₂ H ₄ O) ₃ CH ₃ , G ⁴ = -C ₃ H ₆ O (C ₂ H ₄ O) ₃₀ CH ₃ ]
And having a melting point of 35 to 36 ° C. and a viscosity at 40 ° C. of 5,600 cS.

4) Dimethylpolysiloxane A: Both ends of the molecular chain are blocked with trimethylsilyl groups and have a viscosity of 5,000 cS. 5) Dimethylpolysiloxane B: Both ends of the molecular chain are blocked with monohydroxydimemethylsilyl groups. Viscosity of 3,000 cS, 6) Finely powdered silica Aerosil 300 [trade name of Nippon Aerosil Co., Ltd., specific surface area 300 m ² / g] 7) Silicone resin A (CH ₃ ) ₃ SiO _1/2 unit and SiO ₂ unit consisting of only, (CH _{3) 3} SiO
_1/2 / SiO ₂ = 0.85 8 ones (molar ratio)) silicone resin B (CH ₃₎ composed of only ₃ SiO _1/2 units and SiO ₂ units, (CH _{3) 3} SiO
_1/2 / SiO ₂ = 1.1 (molar ratio)

Examples 1-8, Comparative Examples 1-6 Fast Gemble-TGR as a pigment [trade name of Dainippon Ink and Chemicals, Inc.] 20 parts, water-based ink varnish John Krill 62 [manufactured by Johnson Co., Ltd.] Product name] 30 parts, John Krill 89 (product name of the company) 15 parts, isopropanol 5
Parts, 4 parts of polyethylene wax and 26 parts of water are mixed uniformly, and 100 parts of the aqueous flexo ink composition obtained is added to the silicone antifoam composition A to H prepared as described above.
Then, 0.3 parts by weight of JP and JP were added, and a defoaming test, a defoaming test by a printing machine, and a cissing test were carried out on them, and the results shown in Table 2 below were obtained.

Example 9 Various tests were conducted in the same manner as in Examples 1 to 8 and Comparative Examples 1 to 6 except that 1 part by weight of the silicone antifoam composition I was added, and various tests were conducted. The result as shown in was obtained.

Example 10 Fast Gemble-TGR (previously mentioned) 20 parts, water-soluble resin varnish 1 45 parts, isopropanol 5 parts, polyethylene wax 4 parts, water 26 parts and silicone antifoam composition A
The aqueous ink composition of Example 10 was prepared by mixing and stirring 0.3 parts, and a defoaming test, a defoaming test by a printing machine, and a cissing test were carried out, and the results shown in Table 2 below were obtained. Was obtained.

Example 11 Fast Gemble-TGR (above) 20 parts, water-soluble resin varnish 2 45 parts, isopropanol 5 parts, polyethylene wax 4 parts, water 26 parts and silicone antifoam composition A
The aqueous ink composition of Example 11 was prepared by mixing and stirring 0.3 parts, and a defoaming test, a defoaming test by a printing machine, and a cissing test were conducted. The results shown in Table 2 below were obtained. Was obtained.

[0035]

[Table 2]

[0036]

INDUSTRIAL APPLICABILITY The present invention relates to a low-foaming aqueous ink composition, which comprises (A) a colorant,
(B) a silicone-based defoaming agent composition consisting of (B) a binder resin which is in a dissolved state or an emulsion state in water and (C) the following a) to d), a) a polyoxyalkylene group-containing organopolysiloxane, and b) dimethylpoly Siloxane, c) finely divided silica, d) R ⁴ ₃ SiO _1/2 unit, SiO ₂
Unit, R ⁴ ₂ SiO unit, R ⁴ SiO _3/2 unit, R ⁴ ₃ SiO _1/2
The total amount of units and SiO ₂ units is 80 mol% or more, R ⁴ ₃ SiO _1/2
An organic solvent-soluble silicone resin having a molar ratio of unit / SiO ₂ unit in the range of 0.5 to 1.5 as a main component, and 0.01 to 10% by weight of the component (C) in the entire composition. However, this defoaming agent composition does not break the emulsion even under high temperature and high shearing conditions, exhibits an excellent defoaming effect and durability, and does not cause troubles such as cissing and oil spots. Therefore, the aqueous ink composition to which the silicone-based defoaming agent composition is added has an advantage of exhibiting low foaming property and excellent printability.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location C09D 11/02 PTG (72) Inventor Shuichi Kamiji 1 Hitomi, Daiji, Matsuidada-cho, Usui-gun, Gunma 10 Shinetsu Chemical Industry Co., Ltd. Silicone Electronic Materials Research Laboratory (72) Inventor Satoshi Kuwata 1 Hitomi, Osamu Matsuida-cho, Usui-gun, Gunma Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (72) Inventor Yosuke Tsutsumi Osaka, Osaka 1-23-37 Edobori, Nishi-ku, Sakata, Inc. (72) Inventor Masataka Masataka 1-23-37 Edobori, Nishi-ku, Osaka, Osaka

Claims (1)

[Claims] 1. A silicone-based defoaming agent composition comprising (A) a colorant, (B) a binder resin which is in a dissolved state or an emulsion state in water, and (C) the following a) to d). Formula G _a R ¹ _b SiO _{4-ab / 2} [where G is a general formula -R ² -O- (R ³ -O) _p -Q (wherein R ² is a divalent hydrocarbon group having 1 to 10 carbon atoms) , R ³ is an ethylene group and / or a propylene group, Q is a hydrogen atom or a monovalent organic group selected from an alkyl group having 1 to 8 carbon atoms, an acetyl group and an isocyanic acid group, and p is a natural number). An oxyalkylene group, R ¹ is one or more monovalent hydrocarbon groups having 1 to 18 carbon atoms, and a and b are 0.005 ≦ a ≦ 0.5, 1.4 ≦ b ≦ 2.195 and 1.9 ≦ a + b ≦ 2.2, respectively. ] Polyoxyalkylene group-containing organopolysiloxane represented by 100 parts by weight, b) Viscosity at 25 ° C is 100 to 1,000,000 cS 2 to 200 parts by weight, c) 0.1 to 40 parts by weight of finely divided silica having a specific surface area of 50 m ² / g or more, d) Formula R ⁴ ₃ SiO _1/2 unit, SiO ₂ unit, R ⁴ ₂ A unit selected from SiO units and R ⁴ SiO _3/2 units (where R ⁴ is a monovalent hydrocarbon group having 1 to 6 carbon atoms), and R ⁴ ₃ SiO _1/2 units among all these constituent units. 0.05 to 60% by weight of organic solvent-soluble silicone resin, in which the total amount of SiO ₂ units and SiO ₂ units is 80 mol% or more, and the molar ratio of this R ⁴ ₃ SiO _1/2 unit / SiO ₂ unit is 0.5 to 1.5. 0.01 to 10 parts by weight of the silicone-based defoaming agent composition as a main component, and the component (C) is 0.01% in the total composition.
A low-foaming water-based ink composition, characterized by containing 10 to 10% by weight.