JP5530671B2 - Continuous ink jet ink composition - Google Patents

Description

  The present invention relates to a continuous ink jet ink composition. More specifically, the present invention relates to a continuous ink-jet ink composition having good adhesion to a non-absorbable recording medium and good ejection stability.

  The continuous method, which is one of the inkjet recording methods, records only ink droplets necessary for recording image formation by continuously flying ink droplets and deflecting the flight path with electrical force. It is landed on a medium, and the remaining ink droplets are collected and used repeatedly.

  And in terms of performance, it is excellent in responsiveness because it always keeps ink droplets flying, and it is possible to record at higher speeds, and even with fast drying ink, it has high ejection reliability. It can be said. Due to these features, there are a large number of recording media, and it is highly effective in fields where recording is performed at high speed for a long time, or where fast drying ink is required for non-absorbing recording media. Can therefore be used mainly for industrial purposes.

  In industrial applications, the materials of articles to be recorded are metal, ceramic, glass, plastic, etc., and are extremely diverse regardless of inorganic or organic. Furthermore, there are various materials in plastics, from those with low surface energy such as polyethylene and polypropylene to those with high surface energy such as PET and nylon. Therefore, the ink-jet ink that records and prints on these recording media is required to have good adhesion to various materials. In particular, with the recent expansion of applications, adhesion to a wide range of materials, which has not been heretofore required, is required.

  On the other hand, the ink jet recording method requires ejection stability for ejecting ink droplets from fine nozzles. Further, it is known that the shape of the ink droplet after ejection also affects the formation of a recorded image. Ink stability, ink viscosity, fluidity, surface tension, and other physical properties are a major factor in the ejection stability and ink droplet formation. It can be said that it is easy to get things. Furthermore, the viscosity and fluidity of the ink are affected by the interaction between the resin serving as the binder and the solvent that dissolves it.

  Conventionally, in this type of ink-jet ink composition, as a means for solving such problems, a cellulose derivative is used in the ink as a resin for improving ejection stability under an organic solvent that is a good solvent for the resin. There is a method of using acrylic resin, vinyl chloride-vinyl acetate resin, butyral resin, etc. as a resin to improve the adhesion to the recording medium. However, the resin still provides good ejection stability. There is a problem that it is very difficult to balance both performances, such as inability to adhere or insufficient adhesion.

  Therefore, in order to solve this problem, the present applicant has proposed a continuous inkjet ink composition using a vinyl chloride-vinyl acetate-vinyl alcohol copolymer having an amino group (for example, Patent Document 1).

JP 2008-297446 A

  However, even with the continuous ink jet ink composition described in Patent Document 1, it is difficult to cover all the adhesion to the material of the recording material that has become particularly wide recently, and the recording medium such as stainless steel or polyvinyl chloride is difficult. However, the adhesion to recording media such as polyethylene and polypropylene is still insufficient for the market demand.

  Accordingly, an object of the present invention is to obtain a continuous ink jet ink composition that has good ejection stability and improved adhesion to a recording medium such as polyethylene and polypropylene.

  As a result of diligent research on the resin, the present inventors have used, as a binder, an amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer and a chlorinated polypropylene having a specific chlorination degree in combination. The inventors have found that the discharge stability and the adhesion to a non-absorbing recording medium can be improved, and the present invention has been completed.

That is, the present invention is a continuous inkjet ink composition containing at least a colorant, a resin, and a solvent, wherein the resin is
Resin 1: Amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer, and
Resin 2: contains chlorinated polypropylene having a chlorination degree of 30-50%,
The content of the resin 1 is 2 to 8% by mass in the continuous inkjet ink composition,
The present invention relates to a continuous inkjet ink composition, wherein the content of the resin 2 is 2 to 8% by mass in the continuous inkjet ink composition.

  The proportion of vinyl alcohol units in the total mass of the resin 1 is preferably 4 to 7% by mass.

  It is preferable that the viscosity of the continuous ink-jet ink composition is 2 to 5 mPa · s (25 ° C.).

  According to the continuous ink-jet ink composition of the present invention, a continuous ink-jet ink composition having good ejection stability and improved adhesion to a polyolefin-based recording material such as polyethylene or polypropylene is obtained. Can do.

  Hereinafter, the present invention will be described in more detail.

  Examples of the colorant that can be used in the continuous ink-jet ink composition of the present invention include C.I. I. Solvent Black 22, 23, 27, 29, 34, 43, 47, 123, C.I. I. Solvent Yellow 19, 21, 32, 61, 79, 80, 81, 82, C.I. I. Solvent Red 8, 35, 83, 84, 100, 109, 118, 119, 121, 122, 160, C.I. I. Oil-soluble metal-containing dyes such as Solvent Blue 25, 55 and 70, azo pigments, dioxazine pigments, quinacridone pigments, nitro pigments, phthalocyanine pigments, organic pigments such as various dye lakes, inorganic pigments such as carbon black and titanium oxide Is mentioned. However, the colorants that can be used in the present invention are not limited to these, and these colorants can be used alone or in admixture of two or more.

  The content of these colorants in the ink composition is preferably in the range of 0.1 to 15% by mass. When the content of the colorant is less than 0.1% by mass, the color density decreases. On the other hand, when the content exceeds 15% by mass, it becomes difficult to use from the viewpoint of ink viscosity and fluidity.

  Further, when a pigment such as an organic pigment or an inorganic pigment is used as the colorant, a pigment dispersant is used in combination in order to disperse the pigment. As such a pigment dispersant, those used in the printing technology field can be used, and among them, a polymer dispersant is preferably used, and a carbodiimide dispersant, a polyesteramine dispersant, a fatty acid amine Examples of the dispersant include a dispersant, a modified polyacrylate dispersant, a modified polyurethane dispersant, a polycarboxylic acid dispersant, a multi-chain polymer nonionic dispersant, and a polymer ion activator. Can be used alone or in admixture of two or more. However, the pigment dispersant that can be used in the present invention is not limited thereto. The amount of the pigment dispersant used in an effective range for maintaining good pigment dispersibility is usually 1 to 200 parts by mass, preferably 1 to 60 parts by mass with respect to 100 parts by mass of the total pigment used.

  Furthermore, when a pigment is used as the colorant, it is preferable to add a conductivity imparting agent to the ink composition so that the ejection stability is good. As the conductivity imparting agent, those conventionally used can be used. Specifically, inorganic salts, amine hydrochlorides, quaternary ammonium salts whose anions are organic anions, triallylsulfonium salts and derivatives thereof Etc.

  As the resin used in the continuous ink-jet ink composition of the present invention, an amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer and chlorinated polypropylene can be used in combination.

  First, an amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer that can be used in the continuous ink-jet ink composition of the present invention is basically composed of vinyl chloride and vinyl acetate as essential components, and other components as required. A copolymer obtained by copolymerization by adding a radical polymerizable monomer, saponifying an ester bond derived from vinyl acetate, and further using a compound containing an amino group as another radical polymerizable monomer, or An amino group is introduced by dehydrochlorinating an amino group-containing hydrocarbon compound at a site derived from vinyl chloride.

This copolymer is composed of vinyl chloride units, vinyl acetate units, vinyl alcohol units, and amino group-containing units. The vinyl chloride unit and the vinyl acetate unit are defined as the positions occupied in the copolymer after the reaction of vinyl chloride and vinyl acetate, respectively, with the ethylene chain generated by the cleavage of the unsaturated double bond and the monomer bound to it. A unit composed of residues other than saturated double bonds. That is, the vinyl chloride unit is a unit represented by [—CH ₂ —CHCl—], and the vinyl acetate unit is a unit represented by [—CH ₂ —CH (OCOCH ₃ ) —]. The vinyl alcohol unit is a unit composed of an ethylene chain after the ester bond of a vinyl acetate unit is hydrolyzed by a saponification reaction and a hydroxyl group bonded to the ethylene chain, and [—CH ₂ —CH (OH) — ] Is represented. Furthermore, the amino group-containing unit means that when a compound containing an amino group is used as another radical polymerizable monomer, the ethylene chain generated by the cleavage of the radical polymerizable unsaturated double bond and the unsaturated monomer bonded thereto A unit composed of a residue excluding a double bond, represented by [—CH ₂ —CHX—] (X is a residue excluding an unsaturated double bond of a monomer and containing an amino group), In the case of introducing the amino group-containing hydrocarbon compound into the vinyl chloride unit by dehydrochlorination, the vinyl chloride unit is a unit in which the chlorine in the vinyl group is replaced with a residue excluding one hydrogen of the amino group-containing hydrocarbon compound, [—CH ₂ —CHY—] (Y is a residue excluding one hydrogen of the amino group-containing hydrocarbon compound).

（式中、Ｒ₁は水素原子またはメチル基、Ｒ₂、Ｒ₃は独立に一価の炭化水素基であり、ｍは１〜６の整数である。）で表される（メタ）アクリル酸ジアルキルアミノアルキルエステルが挙げられる。前記一般式（１）において、式：（ＣＨ₂）ｍで示されるアルキレン基としては、メチレン基、エチレン基、トリメチレン基、プロピレン基、テトラメチレン基、ブチレン基等が挙げられる。Ｒ₂、Ｒ₃で示される一価の炭化水素基としては、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基等の炭素原子数１〜４のアルキル基等が挙げられる。前記一般式（１）で表される前記アミノ基含有エチレン性二重結合モノマーの具体例としては、ジメチルアミノエチル（メタ）アクリレート、ジエチルアミノエチル（メタ）アクリレート、ジメチルアミノプロピル（メタ）アクリレート、ジエチルアミノプロピル（メタ）アクリレート等が挙げられる。前記アミノ基含有エチレン性二重結合モノマーとしては、前記一般式（１）で表されるモノマー以外に、ジメチルアミノプロピルアクリルアミド、ジメチルアクリルアミド、アクリルアミド等も使用可能である。 Examples of the method for producing the amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer of the present invention include, for example, a copolymer of vinyl chloride, vinyl acetate, and a monomer having an amino group-containing ethylenically unsaturated double bond. This is saponified and converted into a vinyl alcohol unit by converting a part of the vinyl acetate unit into an amino group-containing unit. The amino group-containing ethylenic double bond monomer is represented by the general formula (1):

(Wherein R ₁ is a hydrogen atom or a methyl group, R ₂ and R ₃ are each independently a monovalent hydrocarbon group, and m is an integer of 1 to 6). And dialkylaminoalkyl esters. In the general formula (1), examples of the alkylene group represented by the formula: (CH ₂ ) m include a methylene group, an ethylene group, a trimethylene group, a propylene group, a tetramethylene group, and a butylene group. Examples of the monovalent hydrocarbon group represented by R ₂ and R ₃ include alkyl groups having 1 to 4 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group and butyl group. Specific examples of the amino group-containing ethylenic double bond monomer represented by the general formula (1) include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylamino And propyl (meth) acrylate. As the amino group-containing ethylenic double bond monomer, in addition to the monomer represented by the general formula (1), dimethylaminopropylacrylamide, dimethylacrylamide, acrylamide and the like can also be used.

  As another method for producing the amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol polymer of the present invention, a vinyl chloride-vinyl acetate copolymer is treated by a saponification / amine modification method in the presence of an amine compound. Then, a method of converting a part of the vinyl acetate unit into a vinyl alcohol unit and reacting a part of the chlorine atom of the vinyl chloride unit with an amine compound to introduce an amino group into the side chain to form an amino group-containing unit. Can be mentioned. Examples of the amine compound include aliphatic amines, alicyclic amines, and aromatic amines. Specifically, ethylamine, propylamine, butylamine, cyclohexylamine, ethanolamine, naphthylamine, aniline, O-toluidine, diethylamine, dibutylamine, diisobutylamine, dioctylamine, diethanolamine, N-methylaniline, trimethylamine, triethylamine, tributylamine , Triisobutylamine, N-methyldiphenylamine, triethanolamine and the like.

  From the viewpoint of ink ejection stability and adhesion to the recording medium, the amino group-containing vinyl chloride-vinyl acetate-vinyl preferably has a vinyl alcohol unit ratio of 4 to 7% by mass in the copolymer. Alcohol copolymers can be used. If the proportion of vinyl alcohol units in the copolymer is less than 4% by mass, the adhesion tends to be reduced, whereas if it exceeds 7% by mass, the discharge stability tends to be reduced.

  In the amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer, the vinyl chloride unit and the vinyl acetate unit are vinyl chloride units / vinyl acetate units = 80/20 to 99/1 in terms of mass ratio. It is preferable to contain in the range.

  Further, the content of the amino group-containing unit in the amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer is preferably 0.1 to 5 mass in the copolymer. When the ratio of the amino group-containing unit is less than the above range, the ejection stability tends to be lowered.

  The amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer preferably has a number average molecular weight in the range of 10,000 to 50,000. When the number average molecular weight exceeds the above range, the viscosity tends to increase and it becomes difficult to discharge from the nozzle.

  Examples of commercial products of the amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol polymer include solvene TAO, solvein TAOL (manufactured by Nissin Chemical Industry Co., Ltd.), and the like.

  The content of the amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol polymer in the ink composition is preferably 2 to 8% by mass. When the content of the amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol polymer is less than 2% by mass, the ejection stability decreases. On the other hand, when the content exceeds 8% by mass, the viscosity increases and non-absorbable recording is performed. Adhesion to the medium is reduced.

  Next, as the chlorinated polypropylene that can be used in the continuous ink jet ink composition of the present invention, any chlorinated polypropylene that can be used in the present invention can be used as long as it can be dissolved in the solvent described later. The degree is preferably 30 to 50%. If the degree of chlorination is less than 30%, the solubility in the solvent described later is lowered. Conversely, if the degree of chlorination exceeds 50%, the adhesion to polyethylene or polypropylene is lowered, which is the object of the present invention. It becomes difficult to improve the adhesion to the material.

  Furthermore, a modified product of chlorinated polypropylene can be used as long as it does not lower the adhesion to polyethylene or polypropylene. For example, a polymerizable acrylic compound (acrylic acid, methacrylic acid or an alkyl ester thereof) or the like is added to these chlorinated polypropylene or Examples include those obtained by graft polymerization of unsaturated polycarboxylic acids (maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, etc.), or chlorinated polyolefins obtained by graft polymerization of the above unsaturated polystruclic acid rubonic acid. It is done.

  The content of the chlorinated polypropylene in the ink composition is preferably 2 to 8% by mass. When the content of the chlorinated polypropylene is less than 2% by mass, the adhesion to a non-absorbing recording medium is deteriorated, and when it exceeds 8% by mass, the ejection stability is deteriorated.

  Solvents that can be used in the continuous ink-jet ink composition of the present invention include monovalent alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, amyl alcohol, benzyl alcohol, cyclohexanol, and diacetone alcohol. , Ethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monoethyl ether and other alkylene glycol monoalkyl ethers, ethylene glycol monoacetate, propylene glycol mono Alkylene glycol monoacetates such as acetate, ethylene glycol , Diethylene glycol, trimethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol and other dihydric alcohols, acetone, methyl ethyl ketone, methyl isobutyl ketone and other ketones, methyl lactate and butyl lactate alkyl lactate Examples include esters and lactones such as γ-butyrolactone.

  It should be noted that both the amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer and chlorinated polypropylene must be soluble in the solvent. Generally, when using chlorinated polypropylene with a high degree of chlorination, a solvent with high polarity may be used, and when using chlorinated polypropylene with a low degree of chlorination, a solvent with a relatively low polarity should be used. It can be said that there are many. Further, the solvent greatly affects the drying property and ejection stability of the ink, and the above solvents can be used alone or in combination of two or more kinds so as to improve the performance.

  Further, the continuous ink-jet ink composition of the present invention includes, as necessary, a pH adjuster, a viscosity adjuster, a rust inhibitor, an antifoaming agent, a silicone surfactant, a fluorine-containing surfactant, and other Additives such as surfactants can also be added.

  Next, a method for producing the continuous inkjet ink composition of the present invention from the above constituent materials will be described.

  For example, (1) when the colorant is a dye, the colorant, amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer, chlorinated polypropylene, solvent, and various additives as required are placed in a sealed container, A method of stirring and uniformly mixing and dissolving, and then filtering with a membrane filter can be used.

  (2) When the colorant is a pigment, a pigment dispersant is dissolved in a part of an organic solvent to form a solution, and the pigment is mixed and stirred, and then kneaded with a kneader to prepare a base ink. In this base ink, the binder resin, the remainder of the organic solvent in which the conductivity-imparting agent is dissolved, and a method of adding and mixing other additives as necessary can be used, but the invention is not limited to these. Absent. Examples of the meat mill include a wet circulation mill, a bead mill, a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, an ultra high pressure homogenizer, a pearl mill, and a high pressure disperser. Among them, a wet circulation mill is preferable because it is necessary to disperse the pigment more finely.

  The viscosity of the obtained continuous inkjet ink composition is preferably about 2.0 to 5.0 mPa · s at 25 ° C.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to this. Unless otherwise specified, “part” and “%” mean “part by mass” and “% by mass”, respectively.

Examples 1-3 and Comparative Examples 1-12
<Preparation of continuous ink jet ink composition>
The composition shown in Table 1 below (the mixing ratio of each component represents mass%) was stirred and uniformly dissolved in a closed container, and then filtered through a 10 μm membrane filter. Inkjet ink compositions of Comparative Examples 1 to 12 were obtained.

(* 1) MEK: Methyl ethyl ketone (solvent)
(* 2) Solvain TAO: Amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer resin (vinyl chloride unit / vinyl acetate unit / vinyl alcohol unit / amino group-containing unit = 88/2/7/3 mass ratio) , Number average molecular weight: 15,000, manufactured by Nissin Chemical Industry Co., Ltd. (* 3) UCAR Solution VinylResin VROH: vinyl chloride-vinyl acetate-hydroxyalkyl acrylate copolymer resin (vinyl chloride unit / vinyl acetate unit / hydroxyl (Alkyl acrylate unit = 81/4/15 mass ratio), molecular weight: 15,000, manufactured by Dow Chemical Co., Ltd. (* 4) CAB381-0.5: cellulose acetate butyrate: acetyl group substitution degree 13.5%, butyryl Group substitution degree 38.0%, manufactured by Eastman Chemical Co. (* 5) Chlorination P (A): chlorinated polypropylene, chlorination degree of 41%
(* 6) Chlorinated PP (B): Chlorinated polypropylene, chlorination degree 62-66%
(* 7) Chlorinated PP (C): Chlorinated polypropylene, chlorination degree 70%
(* 8) Chlorinated PP (D): Chlorinated polypropylene, chlorination degree 20%
(* 9) Orazole Black RLI: Solvent Black 29: Ciba Specialty Chemicals Co., Ltd. (* 10) BYK333: Polyether-modified polydimethylsiloxane, manufactured by Big Chemie

<Performance evaluation>
The viscosity, ejection stability, intermittent ejection property, and adhesion of each ink jet recording ink composition were evaluated by the following methods. The results are shown in Table 1.

[viscosity]
Using an ELD viscometer manufactured by Tokyo Keiki Co., Ltd., measurement was performed at a measurement temperature of 25 ° C. and a measurement rotation speed of 100 rpm.

[Discharge stability]
Using a continuous ink jet printer (A300 manufactured by Domino), it was continuously operated at room temperature for 100 hours and printed on an OPP film (P-2161, 25 μm manufactured by Toyobo Co., Ltd.).
A: Characters are clearly printed during continuous operation B: Characters are printed but difficult to read C: Characters are not printed

[Intermittent discharge]
Using a continuous ink jet printer (Domino A300) for 100 hours of continuous operation, left for 50 hours, then ejected ink again and printed on OPP film (Toyobo Co., Ltd. P-2161, 25 μm) did.
A: Characters are printed neatly B: Characters are printed but difficult to read C: Characters are not printed

[Adhesion]
After printing on an OPP film (Toyobo Co., Ltd., P-2161, 25 μm), it was peeled off immediately after pressing five times with cello tape (registered trademark) (transparent beautiful color, manufactured by Sumitomo 3M Co., Ltd.).
A: No peeling at all B: Some peeling off C: Most peeling off

  By using the ink composition according to the present invention in a continuous ink jet recording system, the adhesion to non-absorbable recording media such as polyethylene and polypropylene is improved while maintaining good ejection stability. This makes it possible to obtain a high-quality printed matter.

Claims (3)

A continuous inkjet ink composition containing at least a colorant, a resin, and a solvent, wherein the resin is
Resin 1: Amino group-containing vinyl chloride-vinyl acetate-vinyl alcohol copolymer, and
Resin 2: contains chlorinated polypropylene having a chlorination degree of 30-50%,
The content of the resin 1 is 2 to 8% by mass in the continuous inkjet ink composition,
The continuous ink-jet ink composition, wherein the content of the resin 2 is 2 to 8% by mass in the continuous ink-jet ink composition.   The continuous ink-jet ink composition according to claim 1, wherein the proportion of vinyl alcohol units in the total mass of the resin 1 is 4 to 7 mass%.   The continuous inkjet ink composition according to claim 1 or 2, wherein the continuous inkjet ink composition has a viscosity of 2 to 5 mPa · s (25 ° C).