KR101117360B1 - Oil-based inks for inkjet printers - Google Patents

Abstract

assignment

In the pigment type piezo inkjet inkjet printer, there is no ink clogging in the printer nozzle during printing, and the ink ejection property and ejection recovery performance are excellent, It is to provide an ink excellent in fixing property and drying property.

Solution

1 per 100 parts by mass of a compound containing a fixing resin, a pigment and a solvent, wherein the solvent contains a cyclic ester and a compound represented by the general formula (1), and the amount of the cyclic ester is represented by the general formula (1) It is an oil-based ink for piezo-type inkjet printers, characterized by -60 mass parts.

{X <_1> in the said General formula (1) represents an alkyl group, X <_2> represents a hydrogen atom or an alkyl group, n represents the integer of 1-4.}

Preferably, said cyclic ester is a compound represented by following General formula (2).

{X <_3> and X <_4> in the said General formula (2) respectively independently represent a hydrogen atom, a C1-C7 alkyl group, or an alkenyl group, m shows the integer of 1-3.}

Description

Oil-based ink for inkjet printers {OIL-BASED INKS FOR INKJET PRINTERS}

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an oil-based ink for pigment type piezo inkjet printers (hereinafter sometimes referred to simply as "inks"), and in detail, there is no ink clogging in the printer nozzle, and ink ejection properties The present invention relates to an ink which is excellent in properties and discharge recovery properties and which is excellent in fixing property and drying property of ink to a recording material.

Conventionally, in the inkjet recording method, a continuous method of selectively landing ink that is continuously discharged onto an adherend such as paper, and a drop-on-demand that selectively discharges ink. On demand, drop-on-demand printers have become mainstream in recent years. The drop-on-demand printer includes a bubble method for discharging ink by bubbles (bubbles) generated by heating the ink rapidly, and a piezoelectric method for discharging ink by using a ceramic (piezoelectric element) that deforms when a voltage is applied. .

The piezoelectric formula using conventional oil-based ink is a method of discharging ink by using a piezo element as a pump and converting electrical energy into mechanical energy, so that various ink materials can be basically discharged. . However, since this method discharges ink with or without a signal, the solvent in the ink is evaporated at the nozzle end face at which the ejection of the ink is stopped. Since discharge of ink is inhibited by loading or the viscosity increase of the ink in the nozzle accompanying the concentration of ink, diligent maintenance is required. In particular, in order to use the non-absorbing base material which is a plastic film, such as a polyvinyl chloride sheet, as a printing base material, the ink used for preparation of the printed object for outdoor uses the relatively high volatility solvent as an ink solvent, for this reason, The drying of the ink is quick and the loading of the ink occurs remarkably.

In addition, when the amount of air dissolved in the ink exceeds a certain amount, with the generation of cavitation due to the high frequency vibration of the piezo element, the micro bubbles generated in the printer nozzle absorb the pressure, and the driving responsiveness may be deteriorated. do. In addition, an abnormality in discharge may be attracted by the generation of bubbles in the nozzle accompanying the change in ambient temperature.

From the above, an ink jet pigment ink (Japanese Patent Laid-Open No. 2003-96370) using a high boiling point solvent instead of the conventional oil-based ink has been proposed. However, in the ink specified in Japanese Patent Laid-Open No. 2003-96370, only a glycol ether ester alone or two or more kinds are mixed as a non-aqueous organic solvent and used for the purpose of not causing thickening or pigment aggregation of the ink in storage. Therefore, the solubility in a solvent of a solid component such as resin in the ink is improved, but when used in the piezoelectric inkjet printer as described above, sufficient ink ejection property is not obtained, and printing is temporarily suspended. If the printing is interrupted and the printing is continued again, the ink discharge recovery performance is lowered, and printing of stable quality cannot be obtained.

Accordingly, an object of the present invention is to provide a pigment-type piezoelectric inkjet printer oil ink, in which there is no ink clogging in the printer nozzle during printing, which is excellent in ejection and ejection recovery of ink, and fixing property to a recording material. And an ink excellent in drying properties.

The above object is achieved by the following invention. That is, this invention contains a fixing resin, a pigment, and a solvent, The said solvent contains the compound represented by following General formula (1) (hereinafter referred to as "Compound A"), and a cyclic ester, and the said ring The amount of a shape ester is 1-60 mass parts per 100 mass parts of compound A, The oily ink for piezo-type inkjet printer is provided.

{X <_1> in the said General formula (1) represents an alkyl group, X <_2> represents a hydrogen atom or an alkyl group, n represents the integer of 1-4.}

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, compared with the pigment type oil ink which used the conventional solvent, especially when it uses for a piezo type inkjet printer, the cross section of a printer nozzle is carried out in printing. In the nozzle with no ink loading in the printer nozzle due to the precipitation of solids in the ink, and the printing is stopped once and the printing is continued again, the ink nozzles have excellent ink discharge recovery characteristics, and It was found that the ink was excellent in the fixing property and drying property of the ink to the recording material without deterioration in ink discharging property due to the viscosity increase of the ink.

Carrying out the invention  Best form for

Best Mode for Carrying Out the Invention The present invention will be described in more detail with reference to the best mode for carrying out the invention. The solvent which mainly characterizes this invention is a mixture of compound A and a cyclic ester, and the quantity of the said cyclic ester is 1-60 mass parts per 100 mass parts of compound A. In the ink containing each of Compound A and the cyclic ester alone as a solvent, the ejectability of the ink from the printer nozzle at the time of printing, the fixability to the recording material, and the dryness are not sufficient. In the present invention, when the compound A and the cyclic ester are mixed and used as a solvent of the ink at an appropriate ratio, when printing using the ink and the piezo-type inkjet printer, precipitation of solids in the ink at the nozzle end surface or the nozzle Increasing the viscosity of the ink due to the ink concentration in the inside of the ink prevents the loading of the ink on the nozzle, and the ejection property and the discharge recovery property of the ink are improved.

If the blending amount of the cyclic ester is too large, the pigment dispersibility and the storage stability of the ink can be lowered, and repelling of the ink occurs depending on the type of recording material. On the other hand, when the blending amount of the cyclic ester is too small, precipitation of solids in the ink or viscosity increase of the ink due to ink concentration in the nozzle is attracted to the nozzle end face of the piezoelectric inkjet printer, and The anti-loading property, the ink discharging property, and the discharge recovery property are significantly reduced.

Examples of the compound A include monomethyl ether acetate of ethylene glycol, monoethyl ether acetate and monobutyl ether acetate, and monomethyl ether acetate of propylene glycol, and n-propyl ether acetate of diethylene glycol and n-. Butyl ether acetate, ethyl ether acetate of triethylene glycol, n-butyl ether acetate, and the like, and particularly preferably monobutyl ether acetate of ethylene glycol.

In addition, in the piezoelectric inkjet printer, the above-mentioned cyclic ester cannot obtain a sufficiently satisfactory result with Compound A alone, and the ink due to the precipitation of solids in the ink at the nozzle end face or the ink concentration in the nozzle It is used for the purpose of suppressing an increase in viscosity and further improving the ejection and ejection recovery properties of the ink.

Said cyclic ester is cyclic ester compounds, such as (beta)-lactones, (gamma)-lactones, delta-lactones, (epsilon) -lactone, etc. of liquid at normal temperature which contains an ester functional group in a ring, Preferably it is the following general formula The cyclic ester compound represented by (2) is mentioned.

{X <_3> and X <_4> in the said General formula (2) respectively independently represent a hydrogen atom, a C1-C7 alkyl group, or an alkenyl group, m shows the integer of 1-3.}

As a cyclic ester represented by said general formula (2), For example, (gamma), such as (gamma) -butyrolactone, (gamma) -valerolactone, (gamma) -caprolactone, (gamma)-caprylolactone, (gamma)-laurolactone, etc. ? -Lactones such as? -Lactones such as -lactone and? -Valerolactone, and? -Caprolactone. Among the above lactones, γ-butyrolactone and / or γ-valerolactone are particularly preferable.

Moreover, it is preferable that the total amount of said compound A and cyclic ester is an amount which occupies 80-98 mass% in all the ink. When the total amount exceeds the upper limit, the printability of the obtained ink is lowered. On the other hand, when the total amount is less than the lower limit, the viscosity of the ink is attracted, and the ejectability of the ink from the nozzle is lowered.

Moreover, the thing whose boiling point of said compound A and cyclic ester is 130-250 degreeC is used preferably. If the boiling point is too high, the dryness of the ink is lowered, leading to blocking of the printed matter. On the other hand, when the boiling point is too low, the obtainable ink dries too fast, causing clogging of the ink in the printer nozzle. Boiling points outside the above ranges lower the printability.

In addition, the fixing resin used in the present invention is a water-insoluble resin that specifically fixes a pigment, which is a colorant, to a printing substrate, and is a known natural or synthetic resin that is soluble in the compound A and the cyclic ester. Anything that doesn't interfere can be used. As said fixation resin, Acrylic resin; Vinyl resins such as vinyl chloride / vinyl acetate copolymer resin, polyvinyl acetate resin and butyral resin; Polyester-based resins; Polyamide-based resins; Fiber-based resins; Epoxy resins; Rosin derivatives such as rosin-modified phenol resins; Preferable examples of the petroleum resin include acrylic resins and vinyl chloride / vinyl acetate copolymer resins. Such fixing resins may be used alone or in combination of two or more thereof.

As said acrylic resin, the polymer which consists of (meth) acrylate {(meta) acrylate means both an acrylate and a methacrylate}, its copolymer, etc. are mentioned. As said (meth) acrylate, For example, Alkyl (meth) acrylates, such as ethyl (meth) acrylate, propyl (meth) acrylate, or butyl (meth) acrylate; Hydroxyalkyl such as hydroxymethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxypentyl (meth) acrylate ( Meth) acrylate, etc. are mentioned. Specifically as said polymer and copolymer, For example, a methyl methacrylate polymer, a methyl methacrylate / butyl methacrylate copolymer, methyl methacrylate / butyl acrylate / hydroxyethyl methacrylate / Methacrylic acid copolymer, styrene / (meth) acrylate copolymer, and (meth) acrylate as a main component, acrylic acid, methacrylic acid, styrene, acrylamide, vinyltoluene, glycerin methacrylate And copolymers of comonomers such as dill and hydroxyethyl acrylate, and mixtures thereof. As an example of said acrylic resin, it can obtain from the Rohm and Haas Company as a brand name of [PARALOID B-66], and can use it for this invention.

As the vinyl chloride / vinyl acetate copolymer resin, for example, a vinyl chloride / vinyl acetate copolymer, a vinyl chloride / vinyl acetate / maleic acid copolymer, a vinyl chloride / vinyl acetate / vinyl alcohol copolymer, and the like, and these And mixtures thereof. As an example of said vinyl chloride / vinyl acetate type copolymer resin, it can obtain from the Dow Chemical Japan company as a brand name of [VYHH], and can use it for this invention.

In addition, said acrylic resin and vinyl chloride / vinyl acetate type copolymer resin can be used individually, respectively, or can use each resin together. When using the said resin together, as for the compounding ratio, acrylic resin / (vinyl chloride / vinyl acetate type copolymer resin) = 1 / 1-9 / 1 (mass ratio) is preferable. It is preferable to use such a fixing resin in the ratio of 1-10 mass% in the whole ink volume.

Moreover, as a pigment used for the ink of this invention, phthalocyanine series, such as phthalocyanine blue and phthalocyanine green, pyransron system, such as carbon black, pyranthrone orange, pyranthrone red, permanent red 2B, a pig, for example Soluble azo pigments such as menthol scarlet and litolid, insoluble azo pigments such as benzidine yellow, hansa yellow, toluidine red, and quinophthalones such as quinophthalone yellow, thioindigo based, and benzimidazolone Organic pigments such as anthraquinones, dioxazines, diketopyrrolopyrroles, isoindolinones and quinacridones; Inorganic pigments such as titanium oxide, ultramarine blue, orange blue, red iron oxide, zinc white, calcium carbonate and barium sulfate. It is preferable to use these pigments in the ratio of 0.5-8 mass% in ink whole quantity.

In addition, in the ink of the present invention, additives such as a polymer dispersant, a surfactant, a plasticizer, an antistatic agent, a viscosity modifier, an antifoaming agent, an antioxidant, and an ultraviolet absorber are added as necessary to the extent that does not prevent the achievement of the object of the present invention. Can be used. As said polymeric dispersing agent, a principal chain consists of polyester type, polyacrylic type, polyurethane type, polyamine type, polycaprolactone type macromolecule etc., for example, and it is an amino group, a carboxyl group, a sulfone group, and / or a hydroxyl group as a side chain. Preferably, a polyester type polymer dispersing agent, such as a dispersing agent which has polar groups, such as a real group, is mentioned.

The ink of this invention mixes and distributes said each component uniformly by a well-known method, and is prepared. The preparation method is, for example, by dispersing the dispersant and the pigment in the solvent as described above, and uniformly kneading and dispersing with 0.3 mm zirconia beads for 3 hours to prepare a pigment dispersion, wherein the fixing resin And solvent are added to prepare ink. Preferably, ink viscosity is prepared so that 8-15 mPa * s and a flash point may be 60 degreeC or more in 25 degreeC. In addition, an ink viscosity is the value measured with the Japan's SiberHegner made by the falling-ball viscometer (AMVn). If the ink viscosity is too high, ink clogging tends to occur in the printer nozzle, and the head needs to be heated in order to lower the viscosity, which causes solvent in the ink to easily evaporate, which further increases the ink clogging. On the other hand, when ink viscosity is too low, printability will fall. Printing to well-known recording materials, such as plastic films, such as a polyvinyl chloride film, by the said ink can be printed using a normal piezo type inkjet printer.

Example

Next, an Example and a comparative example are given and this invention is demonstrated further more concretely. The phrase 'negative' or '%' in the sentence is based on mass unless otherwise specified. In addition, this invention is not limited to the following example.

(Examples 1 to 4)

Using the following fixing resin a, pigment b, and solvent c, the mixtures were formulated as shown in Table 1 and uniformly kneaded and dispersed so that the ink viscosity was 8 to 15 mPa · s at 25 ° C to prepare inks R1 to R4 of the present invention. . In addition, the fixing resin a, the pigment b, and the solvent c in Table 1 are performed as follows.

? Fixed Resin a:

   a1 = acrylic resin (Rom & Haas Co., Pararoid B-66)

   a2 = vinyl-type resin (made by Dow Chemical Japan, VYHH)

Pigment b:

   Phthalocyanine blue

 Solvent c:

   c1 = ethylene glycol monobutyl ether acetate

   c2 = γ-butyrolactone

   c3 = γ-valerolactone

TABLE 1

              Example     One     2     3     4             Ink    R1    R2     R3    R4

ingredient

 Pigment Pigment a      a1    8.0     -    4.0    4.0      a2     -    6.0    4.0    4.0            Pigment b    3.0    3.0    3.0    3.0    Solvent c      c1   57.5   59.5   57.5   57.5      c2   30.0     -   30.0   15.0      c3     -   30.0     -   15.0 Polyester Polymer Dispersion System    1.5    1.5    1.5    1.5

In addition, the numerical value in a table | surface is a negative number.

Comparative Example 1

Ink S1 of Comparative Example was prepared in the same manner as in Example 2 except that 59.5 parts of ethylene glycol monobutyl ether acetate were replaced with 89.5 parts of propylene glycol monomethyl ether acetate without using γ-valerolactone in Example 2. .

Comparative Example 2

Ink S2 of the comparative example was prepared in the same manner as in Example 2 except that γ-valerolactone in Example 2 was replaced with cyclohexanone.

Comparative Example 3

Ink S3 of the comparative example was prepared in the same manner as in Example 3 except that γ-butyrolactone in Example 3 was replaced with cyclohexanone.

In each of the above-obtained inks, a 200 μm polyvinyl chloride film (KANBO PRAS manufactured by Kanbo Pras Co., Ltd., trade name 'WIDEFLEX) was used as a printing material in a discharge evaluation tester equipped with a 256-head nozzle of a piezo-type SPECTRA NOVA. -PL4 '), the ink ejectability at the time of printing, the fixability of ink, and dryness were evaluated by the following measuring methods. The evaluation results are shown in Table 2.

(Ink ejectability)

After printing for a few seconds, printing stops, the head is left and printing is started again, and five or more nozzles of ink ejection defects which are discharged or bent or cannot be discharged from the head nozzle immediately after printing do not go straight. It evaluated as the leaving time of the head until it did.

Score

A: The leaving time of the head until five or more nozzles of ink discharge defects generate | occur | produce is 5 minutes or more.

B: The leaving time of the head until five or more nozzles with poor ink ejection appear is 2 minutes or more and less than 5 minutes.

C: The leaving time of the head until five or more nozzles of ink discharge defects generate | occur | produce is less than 2 minutes.

(Fixability of Ink)

Beta printing and character printing were performed, and the printing surface was rubbed with a finger immediately after printing, and the ink contamination state and peeling state of the ink on the printing surface were visually evaluated.

Score

A: No contamination or peeling of ink on the printing surface is recognized.

B: Contamination and peeling of ink on the printing surface are recognized.

(Ink drying)

After printing, the dry-to-the touch time was measured by hand, and the dryness was evaluated based on the following criteria.

Score

A: The time of contact and drying by hand is less than 3 minutes.

B: The time of drying by contact with a hand is 3 minutes or more.

Table 2

          Example       Comparative Example    One    2    3    4    One    2   3         Ink   R1   R2   R3   R4   S1   S2   S3
Properties  Ink ejectability    A    A    A    A    C    B    B  Ink fixability    A    A    A    A    A    A    A  Ink drying    A    A    A    A    A    A    A

From the ink ejection property of the evaluation result, even if the ink of the present invention is repeatedly printed, practically, ink ejection failure from the nozzle is unlikely to occur, and discharge recovery is good even if the print head is left unattended. It has been demonstrated that the adhesion of the ink to the recording material is excellent from the fixing property of the film, and that the printing of the ink does not cause the blocking of the printing material even if the printing is continuous.

According to the present invention, by replacing the solvent in the pigment type oil ink with a specific mixture solvent, in particular, when used in a piezo inkjet printer, the precipitateability of solids in the ink on the end face of the printer There is provided an ink which does not increase in viscosity due to ink concentration in the nozzle, and which is excellent in ejection property and ejection recovery property of ink from a printer nozzle, fixing property of ink to a recording material, and drying property.

According to the ink of the present invention, there is no clogging of ink to the printer head nozzle even if the printing is continuous, and ink discharge recoverability is good even if the head is left between printing elements. It is excellent in this and can be effectively used as ink for piezo inkjet printers.

Claims (13)

A fixing resin, a pigment, and a solvent, wherein the solvent contains ethylene glycol monobutyl ether acetate and a cyclic ester, and the cyclic ester is at least one of γ-butyrolactone and γ-valerolactone, and the ring The amount of the shape ester is 1 to 60 parts by mass per 100 parts by mass of ethylene glycol monobutyl ether acetate, and the fixing resin is at least one resin selected from the group consisting of acrylic resins and vinyl chloride / vinyl acetate copolymer resins. Oil-based ink for piezo inkjet printers. delete delete The oily ink for a piezo inkjet printer according to claim 1, wherein the total amount of the ethylene glycol monobutyl ether acetate and the cyclic ester is 80 to 98% by mass in the total ink. delete delete delete delete The oily ink for a piezo inkjet printer according to claim 1, wherein the fixing resin is a mixture of an acrylic resin and a vinyl chloride / vinyl acetate copolymer resin having a mass ratio of 1/1 to 9/1. The oily ink for a piezo inkjet printer according to claim 1, wherein the viscosity is 8 to 15 mPa · s at 25 ° C. The oily ink for a piezo inkjet printer according to claim 1, having a flash point of 60 ° C or higher. The oily ink for a piezo inkjet printer according to claim 1, further comprising a polymer dispersant. 13. The oily ink for a piezo inkjet printer according to claim 12, wherein the polymer dispersant is a polyester-based polymer dispersant.