JPH0333172A - Nonaqueous ink for jet printing - Google Patents

Abstract

PURPOSE:To improve the adhesive properties of a marking film after baking, visiblity of the marking film after a high-temp. baking, and storage stability by compounding a solvent-sol. silicone resin, a heat-resistant inorg. coloring pigment, solvent-insol. resin particles, and a solvent as the main components. CONSTITUTION:A nonaqueous ink is pred. by compounding a solvent-sol. silicone resin; a heat-resistant inorg. coloring pigment having a mean particle diameter of 3mum or lower; solvent-insol. resin particles having a mean particle diameter of 3mum or lower; and a solvent capable of dissolving the silicone resin. A pref. silicone resin is one which has a number average mol.wt. of about 2000-10000 to obtain a good adhesion of a marking film before baking (e.g. from room temp. to 800 deg.C) and to obtain a sufficient pouring stability of ink droplets from an ink jet printer nozzle. The heat resistant inorg. coloring pigment is used for obtaining visiblity of the marking film, and thus the problem of an inferior visiblity after a high-temp. baking (e.g. at 1350 deg.C) of a marking film wherein a prior-art dye is used can be solved.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a non-aqueous ink for firing jet printing for marking the surface of heat-resistant substrates such as ceramics, metals, and glass.

<Prior Art and Problems to be Solved> In recent years, heat-resistant base materials such as ceramics have been widely used, and along with this, methods of applying markings by firing have been proposed.

Conventionally, screen printing methods and spray printing methods have been widely adopted as marking methods, but there has been a problem in that it is difficult to mark precise patterns. For this reason, jet printing methods that allow marking of precise patterns have been considered.

Incidentally, ink used for jet printing needs to leave a marking film after baking, so it contains metal-containing dyes and inorganic coloring pigments.

However, jet printing inks usually use acrylic resins, polyester resins, alkyd resins, epoxy resins, etc. as binder resins, so when baked at a temperature of 1000°C or higher, for example, the binder resin does not remain on the marking film, and the marking film contains no binder resin. Only metallic dyes or inorganic colored pigments are required. This has caused problems such as insufficient adhesion of the marking film.

Further, when a metal-containing dye is used, although the ink has excellent storage stability, there is a problem in that the visibility of the marking film is greatly reduced when it is fired at a temperature of 1350° C. or higher.

On the other hand, when heat-resistant inorganic color pigments' are used, 1350
Although the visibility of the marking film is good even when fired at a temperature of .degree. C. or higher, there are problems with the storage stability of the ink, such as the inorganic colored pigments tend to settle and aggregate, and redispersion is difficult.

In view of this current situation, the present inventors have found that the jet printing method, which allows marking of precise patterns, has good adhesion of the marking film after firing, and that the marking film remains stable even when fired at temperatures of 1350°C or higher. The present invention was developed as a result of intensive research to develop a jet printing ink that has good visibility and storage stability.

Means for Solving the Problems> That is, the present invention provides the following components: (i) a solvent-soluble silicone resin, (ii) a heat-resistant inorganic colored pigment with an average particle size of 3 μm or less, (iii) an average particle size of 3 μm or less The present invention relates to a non-aqueous ink for firing jet printing, the main components of which are solvent-insoluble resin particles and (iv) a solvent that dissolves the component (i).

The present invention will be explained in detail below.

The solvent-soluble silicone resin (i) which is a constituent component of the ink of the present invention is typically a resin whose main part has the following three-dimensional structure.

(However, R, R2, R5, R1 are methyl groups, ethyl groups,
Any phenyl group. ) In such silicone resins, crosslinking progresses through a dehydration condensation reaction of a small amount of remaining silanol groups (Si○H).
A strong film is formed.

In the present invention, silicone resin is used as the binder resin, so after firing, the organic component is decomposed with acid and the skeleton remains as a silicon dioxide film, so the adhesion of the marking film can be maintained after firing. It is estimated to be.

The number average molecular weight of the silicone resin is approximately 2000 to 10,000, based on the adhesion of the marking film before baking (for example, at room temperature to 800°C) and the ejection stability of ink droplets from the nozzle of an inkjet printer. suitable.

Furthermore, the silicone resin used in the present invention may also be a modified silicone resin in which a silicone resin intermediate is reacted with polyester, acrylic resin, etc. in order to improve adhesion before firing. However, the silicone resin used in the present invention should be one that does not react with moisture, oxygen, etc. in the atmosphere, and those that do are unsuitable because they may cause nozzle clogging.

The heat-resistant inorganic coloring pigment (
ii) is blended to provide visibility of the marking film, and is applied at high temperatures (for example, 1
(350°C or higher) can eliminate poor visibility after firing. Note that the term "heat-resistant inorganic colored pigment" as used in the present invention refers to an inorganic colored pigment that maintains its coloring power even at high temperatures.

Specific examples of the inorganic color pigment (ii) include red iron,
Typical examples include cobalt blue, cerulean blue, chromium oxide, hydrated chromium oxide, cobalt green, cobalt chrome green, cobalt purple, Mars purple, etc., but are not limited to these, and are colored even after firing. Any inorganic coloring pigment having strong properties can be used without any particular restrictions.

The inorganic coloring pigment (ii) should have an average particle size of 3 μm or less in order to prevent nozzle clogging and agglomeration. However, it does not contain inorganic coloring pigments whose particle size is at least larger than the nozzle diameter.

Solvent-insoluble resin particles (
iii) is the inorganic coloring pigment (ii) in the ink.
) to prevent secondary aggregation from occurring, and to improve redispersibility even if the inorganic color pigment precipitates.

The resin particles (iii) include various synthetic resins without particular limitation as long as they are insoluble in the solvent used, such as phenol resins, urea resins, melamine resins, polyester resins, epoxy resins, urethane resins, xylene resins, and vinyl chloride resins. , acrylic resin, styrene resin, polyamide resin, nylon resin, fluororesin, etc. can be used.

Particularly desirable resin particles (iii) are those having a spherical shape, since this improves the storage stability of the ink and prevents nozzle clogging. Also preferred are solvent-insoluble resin particles that are solvent-philic.

Note that the resin particles (iii) should also have an average particle diameter of 3 μm or less in order to prevent nozzle clogging.However, resin particles with a particle diameter larger than at least the nozzle diameter are not included.

The solvent (1v) which is a constituent component of the ink of the present invention may be an organic solvent that dissolves the component (i) and does not dissolve the component (iii), and preferably has good drying properties and anti-bleeding properties. There are no particular limitations, and solvents conventionally used in jet printing non-aqueous inks can be used.

Specifically, alcohols such as methanol, ethanol, and isopropanol, calpitols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether;
Representative examples include ketones such as acetone, methyl ethyl ketone, and cyclohexanone, and aliphatic esters such as ethyl acetate and butyl acetate.

The non-aqueous ink for jet printing of the present invention is mainly composed of the above-described silicone resin (i), inorganic coloring pigment (ii), resin particles (iii) and solvent (iv), and further contains various dyes as necessary. , curing catalyst, modified resin,
Consists of a mixture of conductivity modifiers, surfactants, etc.

In the ink of the present invention, the amount of silicone resin (i) to be blended is suitably 1 to 20% by weight, preferably 2 to 7% by weight, in view of adhesion after baking.

In addition, the amount of the inorganic color pigment (ii) to be blended is 1 to 10% by weight, preferably 2 to 5% by weight from the viewpoint of visibility, ink stability, etc.
Weight % is appropriate.

The appropriate amount of resin particles (iii) is 2 to 20% by weight, preferably 5 to 15% by weight in view of ink stability, film forming properties, etc.

The blending amount of the solvent (iv) is 40 to 95% by weight, preferably 70 to 90% by weight, taking into account the viscosity, surface tension, etc. of the ink.
is appropriate.

The ink of the present invention can also form a marking film in a state where it is dried at room temperature to several hundred degrees Celsius without being fired.Therefore, in order to improve visibility before firing, 0.0% of the solvent-soluble dye is added.
It is preferable to mix 2 to 5% by weight.

The non-aqueous ink for jet printing of the present invention naturally needs to have properties suitable for inkjet printing, so the viscosity of the ink is 1 to 10 CPS/20°C, and the specific resistance is 200 to 200.
3000Ωcm, specific gravity 0.8-1.2, surface tension 2
One adjusted to 0-60 dynes/cI11 should be used.

The ink of the present invention having such composition and properties is
After mixing and stirring each component, the mixture is filtered and purified using a filter with a pore size of 3 μm to provide an inkjet printing ink.

Note that the inkjet printer can be applied to conventionally known printers, such as a charge control method, an ink-on-demant method, or a method in which ink is ejected by a thermal head, etc., as representative examples.

The marking film of jet printed ink is, for example, 10
It is fired at 00 to 1500°C to form a heat-resistant marking film.

<Effects of the Invention> Since the non-aqueous ink for jet printing of the present invention uses silicone resin as the binder resin, not only the adhesion of the marking film before baking but also the adhesion after baking is greater than that of conventional inks. In addition, since heat-resistant inorganic color pigments are used, the visibility of the marking film after firing is good, and since resin particles are also used, secondary aggregation of inorganic color pigments is less likely to occur, and redispersion is improved. The stability of the ink is compromised due to its good properties.

Hereinafter, the present invention will be further explained in detail with reference to Examples. In the examples, "parts" and "%" are expressed on a weight basis.

Examples 1 to 4 and Comparative Examples 1 to 3 The formulations shown in Table 1 were mixed uniformly and then filtered and purified using a filter with a pore size of 3 μm to prepare jet printing inks.

The stability of the ink when the obtained ink was stored for one month at 25°C; the marking film obtained by discharging each of the above inks onto alumina ceramics using an inkjet printer (nozzle diameter 60μ) and drying at room temperature. 600℃,
Visibility and adhesion when baked for 15 minutes; visibility and adhesion when the marking film was baked at 1500° C. for 15 minutes; and the results are shown in the lower column of Table 1.

As is clear from Table 1, the ink of the present invention had good stability, visibility of marking film, and adhesion.

On the other hand, the comparative example in which resin particles (iii) were not blended had poor ink stability. Furthermore, Comparative Example 2, in which a dye was blended instead of an inorganic colored pigment, had poor visibility after firing. Furthermore, Comparative Example 3 in which acrylic resin was blended as a binder
had poor adhesion after firing.

Note 1) Note 2) Note 3) Note 4) Note 5) Note 6) Note 7) Note 8) Note 9) "Bergan D" (Product name manufactured by Dow Corning) Viscosity (25°C) 150CP.

Non-volatile content 42% rRX-915J (trade name manufactured by Nippon Carbide Kogyo Co., Ltd.) Viscosity (25°C) 5000CP; Non-volatile content 60%; Silicone content 20% rOEGALAN LS 50/150 J (Dagu
SSA product name) Viscosity (25℃>12.000CP; Non-volatile content 6
0%; Hydroxyl value 50 “Eposter SJ (product name manufactured by Nippon Shokubai Co., Ltd.) rSP-
500J (trade name manufactured by Toshisha Co., Ltd.) "Pictorialia Pure Blue" (trade name manufactured by Odugaya Chemical Co., Ltd.) Good; Those that redisperse when stirred are defective; Agglomerates remain even after stirring Visual judgment Scraping test on marking film A rubbing test was conducted 50 times in a reciprocating manner.

◎: Does not peel off at all ○: 1-49% peeling X: 50% or more peeling

Claims (1)

[Scope of Claims] The following components: (i) solvent-soluble silicone resin, (ii) heat-resistant inorganic coloring pigment with an average particle size of 3 μm or less, (iii) solvent-insoluble resin particles with an average particle size of 3 μm or less,
and (iv) a solvent for dissolving the component (i).