JP2008297324A - Nonaqueous pigment ink composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous pigment ink composition having excellent adhesion and alcohol resistance after printing. <P>SOLUTION: In this nonaqueous pigment ink composition essentially comprising (1) an organic solvent, (2) a high molecular compound, and (3) a pigment, (1) the organic solvent consists of at least one kind of solvent selected from a group consisting of (1a) glycol ethers and glycol ether acetates, and (1b) 1,3-dimethyl-2-imidazolidinone, a content of the former (1a) is within a range of 35-94 wt.% in the whole ink composition, and a content of the latter (1b) is within a range of 3-30 wt.% in the whole ink composition. In the nonaqueous pigment ink composition, 1-15 wt.% vinyl chloride-vinyl acetate copolymer is contained as (2) the high molecular compound, and a concentration of (3) the pigment is 2-20 wt.% in the whole ink composition. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a non-aqueous pigment ink composition, and more particularly to an ink composition suitable for ink jet printing ink.

  In recent years, with the development of ink jet printing technology, printing on various media other than plain paper has become possible. In addition, the printable medium can be printed on various types of media, and the market is expanding. Along with this, the printed matter after printing has been used more frequently, and the demand has increased.

  A vinyl chloride resin sheet is known as one of general media used for printing advertisements and billboards used outdoors and the like. Conventionally, a vinyl chloride resin sheet has an ink image-receiving layer on its surface, and this layer absorbs ink and develops color. However, recently, due to the technological advancement of printing media and the low cost, an unprocessed vinyl chloride resin sheet without an ink image-receiving layer has been developed, which has a function to increase color development compared to a vinyl chloride resin sheet with an image-receiving layer. Although the ink adhesion function is inferior, the demand is increasing. For this reason, the function which shows a deeper color with respect to the ink to print, and the function which closely_contact | adheres to a vinyl chloride resin sheet are desired.

  In addition, when a medium such as a vinyl chloride resin sheet is used outdoors, dirt adheres and the advertisement function or the like is weakened. For this reason, it is necessary to remove the stain. Generally, as a method for removing the stain, a method of wiping the surface of the medium with a cloth soaked with alcohol or the like is employed. Alcohol resistance is an essential requirement for membranes.

  Conventionally, a non-aqueous ink using an oil-soluble dye as a colorant has been used. However, since various resistances such as weather resistance are weak, it has been difficult to use outdoors for a long time. For this reason, pigments having stronger weather resistance than oil-soluble dyes have attracted attention, and non-aqueous inks using pigments have been developed.

  For example, oil-based pigment inks using organic solvents such as higher aliphatic hydrocarbon solvents and oleyl alcohol as dispersion media have been proposed (see Patent Documents 1, 2, and 3). However, since the proposed solvent has a high boiling point and low volatility, printing this type of ink on a vinyl chloride resin sheet slows the drying speed of the ink, making it impossible to print at an economical speed. Even if it is dried, the adhesion of the ink coating to the vinyl chloride resin sheet cannot be obtained. That is, Patent Documents 1 to 3 do not show any suggestion regarding the organic solvent of the present invention, the adhesive, and the combination thereof. Patent Document 4 proposes an oil-based pigment ink using glycol ether ester as an organic solvent. However, this proposal does not mention any suggestion about the combined use of adhesion resin that realizes adhesion between the ink and the vinyl chloride resin sheet that is the printing substrate, or a solvent that dissolves or swells the surface of the vinyl chloride resin sheet. No. Naturally, the object of the present invention could not be achieved within the technical scope of the proposal.

  Patent Document 5 describes a non-aqueous ink composition in which a specific polyester resin is used and a pigment is dispersed in an alkylene glycol solvent. However, the resin in this ink is a pigment dispersant, and no mention is made of any combination of an adhesive resin that achieves adhesion between the ink and the vinyl chloride resin sheet that is the printing substrate, or a solvent that dissolves or swells the sheet surface. There is no suggestion. The object of the present invention could not be achieved within the scope of this known technique.

  Patent Document 6 discloses an ink composition comprising a pigment, a high-boiling organic solvent that easily disperses the pigment, and an adhesive resin that is soluble in the solvent. There are no special rules for pigments, and known pigments can be used. For organic solvents and adhesive resins, a combination of an organic solvent that easily disperses the pigment at a boiling point of 150 ° C. or higher and an adhesive resin that uniformly dissolves in the solvent is used. Yes. An example of an adhesive resin or a combination of an organic solvent and an adhesive resin is disclosed, but it is an invention made for the purpose of ink used for printing on a permeable material such as paper. There is no mention or suggestion of, and it is impossible to secure adhesion and durability to a PVC sheet with the ink assumed in the scope of the technology.

  In Patent Document 7, a pigment as a colorant, 20 to 90 wt% of an organic solvent polyalkylene dialkyl ether and 1 to 30 wt% of an N-alkyl-2-pyrrolidone as a dispersion medium, a polyester resin and a polyurethane resin as a pigment dispersant and a fixing agent In addition, an oil-based pigment ink composition having any one of vinyl chloride resin and nitrocellulose as an essential component and having a flash point of 63 ° C. or higher is described in claim 1. N-alkyl-2-pyrrolidone, particularly N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone are used as the organic solvent for dissolving the vinyl chloride sheet, and examples of adhesive resins and organic solvents are disclosed. In this proposal, no organic solvent other than N-alkyl-2-pyrrolidone is mentioned as an organic solvent for dissolving the PVC sheet, and there is no suggestion. Further, when a resin having a high glass transition temperature (Tg) is used as the resin used in this ink, the resin itself has poor adhesion to the PVC sheet and alcohol resistance, and as a result, the ink adhesion cannot be obtained. In addition, alcohol resistance such as polyvinyl butyral resin cannot be obtained if it is soluble in alcohol. Furthermore, when a resin having a low molecular weight is used, the alcohol resistance is poor.

  Patent Document 8 proposes an aqueous pigment ink containing N-methyl-2-pyrrolidone that uses an aqueous solvent and dissolves a vinyl chloride sheet, which is different from these oil-based pigment inks. However, with this ink, it is difficult to obtain excellent adhesion to the PVC sheet and alcohol resistance. The technique is a water-based pigment ink and is a separate invention from the present invention.

  Patent Document 9 proposes an ink for ink jet printing using cyclohexanone or isophorone as an organic solvent for dissolving a vinyl chloride sheet. However, cyclohexanone and isophorone have a problem of strong handling and odor. In this proposal, no organic solvent other than cyclohexanone or isophorone is mentioned or suggested as an organic solvent for dissolving the vinyl chloride sheet.

In addition, due to advances in printer heads and the like, those having a higher pigment concentration have appeared, and inks with even higher adhesion and alcohol resistance are expected. Furthermore, while such technological advances have been made, countermeasures against clogging due to ink drying in the printer head must be handled mainly by the ink composition as before.
Japanese National Patent Publication No. 10-507487 JP 2000-38533 A JP 2001-329193 A JP 2003-96370 A JP-A-10-77432 JP 2002-302629 A JP 2006-9027 A JP 2002-363468 A JP 2006-56991 A

  An object of the present invention is to provide a non-aqueous pigment ink composition having excellent adhesion and alcohol resistance after printing.

In the non-aqueous pigment ink composition comprising (1) an organic solvent, (2) a polymer compound, and (3) a pigment as essential components, (1) the organic solvent is (1a) a glycol ether and a glycol ether. At least one selected from the group consisting of acetates, and (1b)
1,3-dimethyl-2-imidazolidinone, and the content of the former (1a) is 35 to 94 wt% in the total ink composition, and the content of the latter (1b) is 3 to 30 wt% in the total ink composition And (2) a vinyl chloride vinyl acetate copolymer as a polymer compound is contained in an amount of 1 to 15 wt% in the total ink composition, and (3) the pigment concentration is 2 to 20 wt% in the total ink composition. It came to provide the characteristic non-aqueous pigment ink composition.

Thus, (1) an organic solvent, (2) a polymer compound, and (3) a non-aqueous pigment ink composition containing a pigment as an essential component, (1) the organic solvent is (1a) glycol ethers and glycol ether acetate. At least one selected from the group consisting of: and (1b)
1,3-dimethyl-2-imidazolidinone, and the content of the former (1a) is 35 to 94 wt% in the total ink composition, and the content of the latter (1b) is 3 to 30 wt% in the total ink composition And (2) a vinyl chloride vinyl acetate copolymer as a polymer compound is contained in an amount of 1 to 15 wt% in the total ink composition, and (3) the pigment concentration is 2 to 20 wt% in the total ink composition. , Excellent adhesion to untreated polyvinyl chloride resin sheet without ink image-receiving layer, etc., and excellent in alcohol resistance, which is an essential requirement for removing stains on printed sheets. A small amount of non-aqueous pigment ink composition can be provided.

  Embodiments of the present invention will be described below.

  The non-aqueous pigment ink composition in the present invention contains (1) an organic solvent, (2) a polymer compound, and (3) a pigment as essential components. The composition of the present invention can achieve the problem to be solved by the invention. Hereinafter, each composition of the present invention will be described.

  In the non-aqueous pigment ink composition of the present invention, 1,3-dimethyl-2-imidazolidinone is preferably used as the organic solvent. This is because the surface of the PVC sheet or the like is slightly dissolved, and the ink adhesion is remarkably improved.

  Examples of organic solvents that dissolve vinyl chloride include ketone compounds such as methyl ethyl ketone, cyclohexanone, and isophorone, and nitrogen-containing heterocyclic compounds such as pyrrolidone. Of these, ketone compounds are designated as organic solvents under the Industrial Safety Standards Law, and are difficult to handle due to their strong odor.

On the other hand, many nitrogen-containing heterocyclic compounds do not fall under the organic solvents of the Industrial Safety Standards Law, and are excellent in safety and odor when used in ink because they are excellent in safety and low in odor. . That is, the nitrogen-containing heterocyclic compound has a performance that is very suitable as an organic solvent for the ink as compared with the ketone compound.

  Among such nitrogen-containing heterocyclic compounds, N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone have low odor and excellent fixability. However, as mentioned above, N-methyl-2-pyrrolidone is safer and more odorous than ketone compounds, but has been confirmed to have reproductive toxicity and developmental toxicity. There are concerns about the impact. On the other hand, 1,3-dimethyl-2-imidazolidinone is superior in safety compared to N-methyl-2-pyrrolidone.

  Further, according to the study by the present inventors, when 1,3-dimethyl-2-imidazolidinone is used, it has stronger adhesion to the PVC sheet than when N-methyl-2-pyrrolidone is used. It was found that it can be obtained. As a result, by using 1,3-dimethyl-2-imidazolidinone as an organic solvent for dissolving the vinyl chloride resin sheet, it has become possible to provide an ink having adhesion more than that of a known technique. Furthermore, since 1,3-dimethyl-2-imidazolidinone has a boiling point of about 220 ° C. and higher than that of N-methyl-2-pyrrolidone of about 202 ° C., it is also effective as an anti-drying solvent for printer heads.

  In the non-aqueous pigment ink composition of the present invention, 1,3-dimethyl-2-imidazolidinone as an organic solvent is preferably contained in an amount of 3 to 30 wt% in the total ink composition. If the content of 1,3-dimethyl-2-imidazolidinone is too low, adhesion will not be obtained, and if it is too high, ink drying will be poor, and it will be difficult to form an ink coating on the PVC sheet. In addition, the adhesion is deteriorated and the surface is uneven, resulting in a decrease in gloss. In the non-aqueous pigment ink composition of the present invention, N-alkyl-2-pyrrolidone can be used in combination with 1,3-dimethyl-2-imidazolidinone as an organic solvent.

  In addition, it is preferable to use at least one selected from the group consisting of glycol ethers and glycol ether acetates in combination with the aforementioned 1,3-dimethyl-2-imidazolidinone as the organic solvent.

  Glycol ethers are diethylene glycol monoalkyl ether, diethylene glycol dialkyl ether, triethylene glycol monoalkyl ether, triethylene glycol dialkyl ether, dipropylene glycol monoalkyl ether, dipropylene glycol dialkyl ether, glycol ether acetates are ethylene glycol monoalkyl ether acetate , Propylene glycol monoalkyl acetate, diethylene glycol monoalkyl acetate and dipropylene glycol monoalkyl acetate can be used in combination of one or more. This is because these solvents have a boiling point of 100 ° C. or more and 250 ° C. or less, so that they have good drying properties after printing, can be printed at an economical speed, and have little influence on the human body because the odor of the solvent is small. .

  In the non-aqueous pigment ink composition of the present invention, the polymer compound is preferably a vinyl chloride vinyl acetate copolymer. Since vinyl chloride vinyl acetate copolymer does not dissolve in water or alcohol, it has water resistance and alcohol resistance after drying the ink in which the polymer is dissolved. Further, since the vinyl chloride vinyl acetate copolymer has a polyvinyl chloride resin as a composition, it has good compatibility with the vinyl chloride resin sheet, and has high adhesion after drying the ink. Furthermore, depending on the polymer composition of the vinyl chloride / vinyl acetate copolymer, some have a pigment dispersion effect, which functions as an adhesion resin and also as a pigment dispersion resin. For this reason, the dispersant may not be used, or the amount of the dispersant may be reduced. In these cases, the amount of the dispersant having a low molecular weight is reduced, thereby further increasing the alcohol resistance. There is an advantageous effect in that the property and adhesion can be obtained.

  The polymer composition of the vinyl chloride vinyl acetate copolymer of the present invention is preferably 80 to 90% vinyl chloride resin composition and 10 to 20% vinyl acetate resin composition. When the vinyl chloride vinyl acetate copolymer is used in the ink as a pigment dispersion resin, the vinyl chloride resin composition is preferably 88 to 90% and the vinyl acetate resin composition is preferably 10 to 12%. This is because if the vinyl chloride resin composition is high, the pigment dispersion function becomes large.

  The vinyl chloride vinyl acetate copolymer in the non-aqueous pigment ink composition of the present invention preferably has a weight average molecular weight of 25,000 to 50,000. If the molecular weight is too low, the alcohol easily penetrates into the ink film after drying, and adhesion is deteriorated, resulting in poor alcohol resistance. On the other hand, if the molecular weight is too high, the viscosity of the ink itself increases, and the fluidity, which is a basic requirement for inkjet inks, cannot be obtained.

  In the vinyl chloride vinyl acetate copolymer in the non-aqueous pigment ink composition of the present invention, the glass transition temperature (Tg) of the polymer compound is preferably 70 ° C. or higher and 90 ° C. or lower. If the glass transition temperature is too low, the drying property of the ink after printing becomes poor, and economical printing cannot be performed. Further, even after the ink is dried, the blocking property is deteriorated, and even when the ink is used at room temperature, the printed matter is sticky, resulting in unevenness on the surface and a decrease in gloss. On the other hand, if the glass transition temperature is too high, the ink film after drying becomes hard and easily broken, and it is difficult to obtain adhesion to the PVC sheet.

  The vinyl chloride vinyl acetate copolymer is preferably contained in the total ink composition in an amount of 1 to 15 wt%, more preferably 1 to 10 wt%. In addition to the excellent effect in alcohol resistance after printing, an excellent effect is also seen in the adhesion to the vinyl chloride resin sheet and the like. If the amount of this resin is small, alcohol resistance and adhesion cannot be obtained, and if it is too large, the viscosity of the ink itself increases, and the fluidity, which is a basic requirement for inkjet ink, cannot be obtained.

  In the present invention, a polymer compound can be added in order to further improve adhesion, alcohol resistance, water resistance, dispersion stability, and printability. Polymers that can be used include acrylic resin, styrene-acrylic copolymer, styrene-maleic acid copolymer, ethylene-vinyl acetate copolymer, petroleum resin, terpene phenol resin, phenol resin, urethane resin, cellulose resin, melamine Examples thereof include resins, urea resins, epoxy resins, vinyl chloride resins, alkyd resins, butyral resins, and maleic acid resins. Among these, the optimum one can be used alone or in combination of two or more.

  In the non-aqueous pigment ink composition of the present invention, the pigment concentration is preferably 2 to 20 wt%. If the pigment concentration is too low, the concentration will be too thin and sufficient color will not be obtained on the printed matter. If the concentration is too high, the viscosity will be high and the fluidity that is the basic requirement of inkjet ink will be obtained. Absent.

  Carbon black, cyan, magenta, and yellow pigments can be used as the pigment.

  Carbon Black is HCF, MCF, RCF, LFF, OCF manufactured by Mitsubishi Chemical, Monarch manufactured by Cabot, Regal, Color Black manufactured by Degussa, Special Black, Printex, Toka Black manufactured by Tokai Carbon, Columbia Raven made of the like can be used.

  As cyan, C.I. pigment blue 1, 2, 3, 15: 1, 15: 2, 15: 3, 15: 4, 16, 22, 60, and the like can be used.

  As magenta, C.I. Pigment Red 5, 7, 12, 57: 1, 112, 122, 123, 168, 184, 202, 209, 254 and the like can be used.

  Yellow is CI Pigment Yellow 1, 2, 3, 12, 13, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 120, 128, 129, 130, 138, 139, 147, 150, 151, 154, 155, 180, 185, 213, 214, etc. can be used.

  In the non-aqueous pigment ink composition of the present invention, a dispersant can be added. Dispersants that can be used include Ajinomoto Fine Techno Co., Ltd. Ajispur, Nippon Lubrizol Co., Ltd. Solsperse, Ciba Specialty Chemicals Co., Ltd. EFKA, Big Chemie Japan Co., Ltd. Disperbyk, Enomoto Kasei Disparon DA manufactured by Co., Ltd. and the like can be mentioned, and among these, the most suitable one can be used in combination with one or more kinds in consideration of dispersibility and stability depending on the kind of pigment.

  The non-aqueous pigment ink composition of the present invention can be used in various ink jet printers. An example of such an ink jet printer is one that ejects ink by an on-demand method. In particular, the ink of the present invention can be suitably applied to printing by a large inkjet printer using a large format.

  The medium in which the ink of the present invention can be used is not limited to an untreated vinyl chloride resin sheet having no ink image-receiving layer, but includes a glossy vinyl chloride resin sheet, a polyester synthetic paper mat, a clear film, a tarpaulin, and a multi-layer. It can be used for a variety of media, such as a media having the same.

 Examples of embodiments of the present invention will be specifically described below with reference to examples. In addition, the part in an Example and a comparative example is a weight part.

Example 1
8 parts of MA-8 (Mitsubishi Chemical Corporation) as a pigment in a 250 cc plastic bottle and 4 parts of vinyl chloride vinyl acetate copolymer VYNS (manufactured by Dow Chemical Co., Ltd., weight average molecular weight 44000, Tg 79 ° C.) as a polymer compound 3 parts Solsperse 32000 (manufactured by Avicia) as a dispersant, 66 parts ethylene glycol monobutyl ether acetate as an organic solvent, 19 parts 1,3-dimethyl-2-imidazolidinone and 400 parts of 0.5 mm zirconia beads The ink composition was prepared by dispersing for 3 hours with a measuring paint conditioner and filtering with qualitative filter paper No. 5C (manufactured by ADVANTEC).

Example 2
An ink composition was prepared in the same manner as in Example 1, except that 5 parts of 1,3-dimethyl-2-imidazolidinone as an organic solvent, 50 parts of diethylene glycol diethyl ether and 30 parts of diethylene glycol dimethyl ether were used.

Example 3
An ink composition was prepared in the same manner as in Example 1 instead of vinyl chloride / vinyl acetate copolymer solvine CN (manufactured by Nissin Chemical Industry Co., Ltd., weight average molecular weight 42000, Tg 75 ° C.).

Comparative Example 1
An ink composition was prepared in the same manner as in Example 1, except that 1,3-dimethyl-2-imidazolidinone was replaced with N-methyl-2-pyrrolidone as the organic solvent.

Comparative Example 2
An ink composition was prepared in the same manner as in Example 1, except that 1 part of 1,3-dimethyl-2-imidazolidinone as an organic solvent and 84 parts of ethylene glycol monobutyl ether acetate were used.

Comparative Example 3
An ink composition was prepared in the same manner as in Example 1, except that 40 parts of 1,3-dimethyl-2-imidazolidinone as an organic solvent and 45 parts of ethylene glycol monobutyl ether acetate were used.

Comparative Example 4
An ink composition was prepared in the same manner as in Example 1 instead of vinyl chloride / vinyl acetate copolymer solvin CNL (manufactured by Nissin Chemical Industry Co., Ltd., weight average molecular weight 12,000, Tg 76 ° C.) as a fixing resin.

Comparative Example 5
An ink composition was prepared in the same manner as in Example 1 instead of vinyl chloride vinegar vinyl copolymer VAGC (manufactured by Dow Chemical Co., Ltd., weight average molecular weight 24,000, Tg 65 ° C.) as a fixing resin.

Comparative Example 6
An ink composition was prepared in the same manner as in Example 1 instead of the polyester urethane resin Byron UR-1400 (manufactured by Toyobo Co., Ltd., weight average molecular weight 40,000, Tg 83 ° C.) as a fixing resin.

Comparative Example 7
An ink composition was prepared in the same manner as in Example 1 instead of cellulose ester resin CAB-531-1 (Eastman, weight average molecular weight 40,000, Tg 115 ° C.) as a fixing resin.

<Clogged nozzle>
Images were printed with a large format inkjet printer, and those that could be printed normally were evaluated as ◯, and those that could not be printed normally due to nozzle clogging were evaluated as ×.

<Fixability>
The ink composition was applied to an untreated vinyl chloride resin sheet using a No. 6 wire bar, and after 2 hours, a scrub test with a finger was performed for 60 seconds. After the test, the case where there was no scrub mark was evaluated as ◎, the case where some scrub mark was generated was evaluated as ◯, the case where scrub marks were generated as Δ, and the case where scrub marks were generated and the substrate was visible was evaluated as ×.

<Alcohol resistance>
The ink composition was applied to an untreated vinyl chloride resin sheet using a No. 6 wire bar, and after 2 hours, the coated surface was rubbed with a cotton swab soaked with an ethanol solution. As a result, it was evaluated that the coated surface was not scraped off at all, and the scraped surface was evaluated as x.

table 1

 From the results shown in Table 1, the ink compositions of Examples 1 to 3 exhibited excellent fixability and alcohol resistance, and had no problem with respect to printability on the vinyl chloride resin sheet, and were excellent.

Claims (3)

(1) An organic solvent, (2) a polymer compound, (3) a non-aqueous pigment ink composition containing a pigment as an essential component, wherein (1) the organic solvent comprises (1a) glycol ethers and glycol ether acetates At least one selected from (1b)
1,3-dimethyl-2-imidazolidinone, and the content of the former (1a) is 35 to 94 wt% in the total ink composition, and the content of the latter (1b) is 3 to 30 wt% in the total ink composition And (2) a vinyl chloride vinyl acetate copolymer as a polymer compound is contained in an amount of 1 to 15 wt% in the total ink composition, and (3) the pigment concentration is 2 to 20 wt% in the total ink composition. A non-aqueous pigment ink composition. Glycol ethers are diethylene glycol monoalkyl ether, diethylene glycol dialkyl ether, triethylene glycol monoalkyl ether, triethylene glycol dialkyl ether, dipropylene glycol monoalkyl ether, dipropylene glycol dialkyl ether, glycol ether acetates are ethylene glycol monoalkyl ether acetate 2. The non-aqueous pigment ink composition according to claim 1, which is at least one selected from the group consisting of propylene glycol monoalkyl acetate, diethylene glycol monoalkyl acetate, and dipropylene glycol monoalkyl acetate. 2. The non-aqueous pigment ink composition according to claim 1, wherein the vinyl chloride / vinyl acetate copolymer has a weight average molecular weight of 25,000 to 50,000 and a glass transition temperature of 70 to 90 ° C.