JPH101630A - Thermally melting ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject ink high in opacity, capable of providing even an OHP paper with an excellent and clear image and carrying out writing by a heated and melted ink, comprising a high-melting wax, a resin having a softening point lower the melting point of the wax and a colorant. SOLUTION: This ink comprises a wax which is solid at a normal temperature and has >=50 deg.C melting point, a resin having a softening point lower than the melting point of the wax and a colorant such as a black dye to give the objective dye having an improved optical concentration on a printing paper, capable of surely forming a shade part (black part) on the projected face of an OHP sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-melt ink used in an ink jet recording apparatus. More specifically, the present invention relates to a heat-meltable ink for recording by heating and melting the ink.

[0002]

2. Description of the Related Art Conventionally, as an ink jet recording system, for example, a so-called electric field control system in which ink is ejected by using electrostatic attraction; a so-called drop-on system in which ink is ejected by using a vibration pressure of a piezoelectric element. Demand method (pressure pulse method); various methods such as a so-called thermal ink jet method have been proposed in which ink is ejected using pressure generated by forming and growing bubbles by high heat, and these are extremely high-definition screens. Can be obtained.

[0003] In these ink jet recording systems, an aqueous ink using water as a main solvent and an oil-based ink using an organic solvent as a main solvent are generally used. Printed images using water-based inks generally have poor water resistance, whereas oil-based inks can provide printed images having excellent water resistance.

However, since these aqueous and oil-based inks are liquid at room temperature, bleeding is liable to occur when printed on recording paper, and sufficient print density cannot be obtained. Precipitates are likely to occur, which has the disadvantage of greatly reducing the reliability of the ink jet recording system.

For the purpose of remedying the drawbacks of these conventional solution-type inks, a so-called hot-melt type oil-based ink for ink-jet recording using a solid ink at normal temperature has been proposed. Specifically, US Pat.
No. 5,393,32 discloses an ink containing a dialkyl sebacate, US Pat. No. 4,390,369.
JP-A-58-108271 discloses an ink containing a natural wax.
No. 973 discloses an ink containing stearic acid, and Japanese Unexamined Patent Publication No. 61-83268 discloses an ink containing an acid or alcohol having 20 to 24 carbon atoms, and further, a ketone having a relatively high melting point with these. JP-A-62-48774 discloses an ink containing a thermosetting resin having a high hydroxyl value, a solid organic solvent having a melting point of higher than 150 ° C., and a small amount of a dye substance. In JP-A-112627, a coloring material, a first solvent that is solid at room temperature and liquefies when heated to a temperature higher than room temperature, and a second solvent that is liquid and highly volatile at room temperature and dissolves the first solvent. Inks comprising a solvent, JP-A-62-295973, have proposed inks containing a synthetic wax having a polar group and a dye soluble in the wax.

[0006]

However, in these hot-melt inks, when the resin and wax are mixed, the softening point of the resin is considered in relation to the melting point of the wax, and the ink having a softening point of the resin lower than the melting point of the wax is used. None of the compositions were fabricated and opacity was enhanced by growing wax crystallization. The reason why the opacity is required is that when the light is projected onto the OHP sheet with the ink attached thereto, a shadow portion (black portion) is reliably formed on the projection surface. Also, in order to form a full-color projected image, the black printed portion on the OHP paper is surely shaded (black) on the projection surface, and the red or yellow printed portion transmits light and has a red or yellow color on the projection surface. Must be projected as a yellow part. Conventionally, in order to produce this opaque ink (hot-melt ink), it is difficult to form black on the projection surface, even if a black dye is put in just as far as the solubility, it will not be completely opaque. Met. Here, the reason for using the hot-melt ink is that the ink does not bleed,
This is because a printed image can be easily attached to an OHP sheet.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has good printing quality such as good adhesiveness and sharpness as an ink.
It is an object of the present invention to provide a hot-melt ink which shows a sufficient density on a P sheet and can surely form a shadow on a projection surface of an OHP sheet.

[0008]

In order to achieve this object, a hot-melt ink according to claim 1 is solid at room temperature and has a melting point at about 50 ° C. or higher;
It comprises a resin and a coloring material, and is characterized in that the softening point of the resin is lower than the melting point of the wax. As used herein, the softening point of a resin refers to a substance measured by a ring and ball method.
However, a crystalline resin may be measured by the DSC method. The melting point of the wax refers to a substance measured by the DSC method.

In the hot-melt ink according to the first aspect, the waxes serve as a main component of the ink and determine the properties of the ink such as thermal properties and viscosity. The resin functions to impart adhesiveness to the printing paper or to control the viscosity of the ink. The coloring material gives a color to the ink composition. Since the softening point of the resin is lower than the melting point of the wax, the crystallization of the wax is not hindered than the fine crystals of the resin, so that it is possible to provide an ink that grows larger and has higher opacity. Since the ink itself has almost no transparency, the optical density on printing paper is improved.
When printing is actually performed using this, a clear image having good and sufficient density can be formed on OHP paper as a matter of course, and a shadow portion ( Black portion).

[0010] In the hot-melt ink according to a second aspect, the coloring material is a black dye. For this reason, the color of the image of the ink adhered to the printing paper or the OHP paper becomes black, and a shadow portion (black portion) can be reliably formed even on the OHP projection surface.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. The hot-melt ink of the present embodiment contains 20 to 80% by weight of a wax having a melting point of 50 to 150 ° C. and a resin 5 to 60 having a weight average molecular weight of 500 or more.
% By weight, 0.1 to 10% by weight of a black dye, preferably 0.1 to 10% by weight.
It comprises 5 to 8% by weight, more preferably 0.5 to 5% by weight as a component.

The wax used in the ink of the present embodiment may be any wax that is fixed at room temperature and can be melted by heating. However, since the room temperature fluctuates depending on the season, the use area, and the use situation, it is almost impossible. At temperatures lower than 50 ° C., solid materials are preferred. The melting point is preferably a temperature that can be easily heated by an ink heating mechanism mounted on the ink jet printer and that does not affect the structure of the printer. In general, commercially available ones up to 150 ° C. are practical because of their availability. Therefore, it is preferable that the melting point of the wax is 50 ° C. to 150 ° C., and that the wax is stable against heat.

Examples of the wax include petroleum wax, desirably paraffin wax or microcrystalline wax, vegetable wax, desirably candelilla wax, carnauba wax, rice wax, jojoba solid wax, animal wax, Preferably beeswax, lanolin or spermaceti, mineral waxes, preferably montan wax, synthetic hydrocarbons,
Desirably Fischer-Tropsch wax or polyethylene wax, hydrogenated wax, desirably hydrogenated castor oil or hydrogenated castor oil derivative, modified wax,
Desirably montan wax derivatives, paraffin wax derivatives, microcrystalline wax derivatives or polyethylene wax derivatives, higher fatty acids, preferably behenic acid, stearic acid, palmitic acid, myristic acid, or lauric acid, higher alcohols, preferably stearyl alcohol, Or behenyl alcohol,
Hydroxystearic acid, preferably 12-hydroxystearic acid or 12-hydroxystearic acid derivative, ketone, preferably stearone or lauron, amine, preferably dodecylamine, tetradecylamine or octadecylamine, ester, preferably stearic acid Methyl, octadecyl stearate,
Glycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, ethylene glycol fatty acid ester, or polyoxyethylene fatty acid ester, or any of conventionally known waxes such as a polymerized wax, preferably an α-olefin maleic anhydride copolymer wax. Can be used without particular limitation.

These waxes can be used alone or as a mixture of two or more kinds.
Desirably, it is contained in the range of 80% by weight. That is, if the content of the wax is less than 20%, the characteristics of the other additives appear on the entire surface, so that the melting point of the ink becomes high or cannot be determined, so that the ink does not melt sharply at the inkjet discharge temperature. . However, this does not apply to cases where other additives are appropriately selected and used in such a manner that their melting points and the melting points of the waxes are substantially equal. On the other hand, when the content exceeds 80% by weight, a sufficient melt viscosity as an ink is not obtained, and the printing paper becomes hard.

The resin used in the present embodiment functions to impart adhesiveness to printing paper or to control the viscosity of ink. Further, a resin having a softening point lower than the melting point of the wax is used. Here, the softening point means an object measured by a ring and ball method. However, a crystalline resin may be measured by the DSC method.
The melting point of the wax refers to a substance measured by the DSC method.

The molecular weight of the resin is determined by gel permeation chromatography using a differential refractometer as a detector or temperature-increased gas chromatography using a thermal conductivity meter as a detector. The weight average molecular weight MW is preferably 500 or more and 5000 or more.
00 or less, and more preferably 600 or more and 400
000 or less, and most preferably 700 or more and 300
000 or less.

The resin is preferably an oil-soluble resin. Examples of the oil-soluble resin include an olefin resin, preferably a polyethylene resin, a polypropylene resin or a polyisobutylene resin, or a vinyl resin, preferably an ethylene-vinyl acetate copolymer resin, a vinyl chloride-vinyl acetate copolymer resin or acetic acid. Vinyl resin or ethylene-vinyl chloride-vinyl acetate resin, acrylic resin,
Desirably, methacrylate resin, polyacrylate resin, ethylene-ethyl acrylate copolymer resin or ethylene-methacrylic acid copolymer resin, phenol resin, polyurethane resin, polyamide resin,
Polyester resin, ketone resin, alkyd resin,
Rosin resin, hydrogenated rosin resin, petroleum resin,
Examples include hydrogenated petroleum resin, maleic acid resin, butyral resin, terpene resin, hydrogenated terpene resin, and chroman-indene resin. These polymer materials may be used alone or as a mixture of two or more kinds. It is desirable that the polymer material is contained in the ink in the range of 5 to 60% by weight. That is, the content is 5% by weight.
If it is less than 3, the melt viscosity is not sufficient as an ink.
On the other hand, if the content exceeds 60% by weight, the melt viscosity becomes high, and it becomes difficult to discharge good ink at the operating temperature of the printer head used for ink jet recording.

As the coloring material used in the present embodiment, any dyes and pigments conventionally used in oil-based ink compositions can be used.

Regarding pigments, those generally used in the technical field of printing can be used regardless of whether they are organic or inorganic. Specifically, for example, carbon black, cadmium red, molybdenum red, chrome yellow, cadmium yellow, titanium yellow, chromium oxide, viridian, titanium cobalt green, ultramarine blue,
Prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, threne pigments, perylene pigments, perinone pigments, thioindigo pigments, quinophthalone pigments, metal complexes Conventionally known pigments such as pigments can be used without any particular limitation. These pigments can be used in combination.

In this embodiment, a black dye is used as a coloring material in order to produce a black ink. Of course, in the case of inks of other colors that require strong opacity of the ink, a dye of that color may be used.

As the black dye, any black dye conventionally used in oil-based ink compositions can be used, but azo dyes, disazo dyes, metal complex dyes, naphthol dyes, anthraquinone dyes, indigo dyes Preferred are black oil-soluble dyes such as carbonium dyes, quinone imine dyes, cyanine dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes, xanthene dyes, phthalocyanine dyes, metal phthalocyanine dyes, and the like. It is also possible to use them in combination. These are 0.1 to 10% by weight in the ink, preferably 0.5 to 8% by weight in consideration of the color developing property of the printer, and assurance that the dye does not precipitate from the ink due to heat change during operation of the printer.
More preferably, it is 0.7 to 5% by weight.

[0022]

【Example】

<Example 1> A room-temperature solid wax as a vehicle in Example 1 was a microcrystalline wax (Hi
Mic 2095, manufactured by Nippon Seiro Co., Ltd., melting point 101
C), stearic acid amide wax (Amide AP-
1. Nippon Kasei Kogyo Co., Ltd., melting point 100 ° C. As the resin, hydrogenated petroleum resin (Alcon P-70, Arakawa Chemical Co., Ltd.)
And a softening point of 70 ° C.). I. Sol
event Black 3 (Oil Black HB
B, manufactured by Orient Industrial Co., Ltd.).

Ink Formulation Hi Mic 2095 53% by weight Amide AP-1 20% by weight Archon P-70 25% by weight Oil Black HBB 2% by weight The hot-melt ink can be manufactured by the procedure shown in FIG. I can do it.

Hi Mic 2095 (2), Amide AP-1 (4) and Archon P-70 (6) were heated at 70 ° C.
Heat and melt at a temperature of about 250 ° C., preferably about 100 ° C. to 200 ° C., and mix Oil Black HBB (8). This is 200-1 by a dissolver (10).
Stir and mix at 0000 RPM, preferably 500-5000 RPM. The prepared ink composition (12) is filtered using a 2 μm mesh filter (14) with a hot filtration device manufactured by Toyo Roshi Kaisha to obtain a final hot-melt ink (16).

The prepared composition (16) was melted on a hot plate heated to 110 ° C.
-2500, manufactured by Sumitomo 3M) with a wire-wound rod (winding diameter: 0.9 mm) to obtain a clear and opaque ink film. Haze meter (Suga Test Instruments Co., Ltd.)
Was 50.6%.

When the above ink was mounted on an ink jet printer and printing was performed, clear printing was obtained on recording paper without clogging of the printer head. Further, it was possible to print well on OHP paper, and the printed matter was sufficiently dark.

Example 2 Room-temperature solid wax as a vehicle in Example 2 was Fischer-Tropsch wax (FTP-1005, manufactured by Nippon Seiro, Ltd., melting point 98).
C), stearic acid amide wax (Amide AP-
1, manufactured by Nippon Kasei Co., Ltd., melting point: 100 ° C., hydrogenated petroleum resin (Alcon P-90, Arakawa Chemical Industries, softening point: 90 ° C.), and oil-soluble dye C.I. I. Soliven
t Black 29 (OlasolBlack RL
I, Ciba-Geigy).

Ink Formulation FTP-1005 60% by weight Amide AP-1 18% by weight Archon P-90 20% by weight Olasol Black RLI 2% by weight The hot-melt ink can be manufactured by the same procedure as in Example 1. I can do it. The FTP-1005, Amide AP
-1, Alcon P-90 is heated and dissolved at a temperature of about 70 ° C. to 250 ° C., preferably about 100 ° C. to 200 ° C .;
Mix lasol Black RLI. This is stirred and mixed with a dissolver at 200 to 10000 RPM, preferably 500 to 5000 RPM. The adjusted ink composition is filtered using a 2 μm mesh filter with a hot filtration device manufactured by Toyo Roshi Kaisha to obtain a final hot-melt ink.

The prepared composition was melted on a hot plate heated to 110 ° C.
0, manufactured by Sumitomo 3M Co., Ltd.
m), a clear and opaque color ink film was obtained. Haze meter (Suga Test Instruments Co., Ltd.)
Was 60.2%.

When the above ink was mounted on an ink jet printer and printing was performed, clear printing was obtained on recording paper without clogging of the printer head.

Comparative Example 1 A room-temperature solid wax as a vehicle in Comparative Example 1 was a microcrystalline wax (Hi-Mic 2095, manufactured by Nippon Seiro Co., Ltd., melting point: 101 ° C.) stearic acid amide wax (Amide A)
P-1, manufactured by Nippon Kasei Kogyo Co., Ltd., melting point: 100 ° C .; hydrogenated petroleum resin (Alcon P-115, manufactured by Arakawa Chemical Industries, softening point: 115 ° C.); oil-soluble dye C.I.
I. Solvent BLACK29 (ORASOL
BLACK RLI, manufactured by Ciba-Geigy).

The ink composition in Comparative Example 1 is as follows.

Ink Formulation Hi-Mic 2095 50% by weight Amide AP-1 20% by weight Archon P-115 28% by weight ORASBLACK RLI 2% by weight The hot melt ink of Comparative Example 1 can be prepared by the following method. it can.

Hi-Mic 2095, Amide AP-
1, Alcon P-115 is heated and dissolved at a temperature of about 70 ° C. to 250 ° C., preferably about 100 ° C. to 200 ° C .;
Mix RASOL BLACK RLI. This is stirred and mixed with a dissolver at 200 to 10000 RPM, preferably 500 to 5000 RPM. The prepared ink composition was passed through a hot filtration device manufactured by Toyo Roshi Kaisha Co., Ltd.
Filter using a μm mesh filter to obtain the final hot melt ink.

The prepared composition was melted on a hot plate heated to 110 ° C.
0, manufactured by Sumitomo 3M Co., Ltd.
m), the transparency was clearly higher than that of the ink of Example 2. It was 20.1% when measured with a HAZE degree meter (manufactured by Suga Test Instruments Co., Ltd.).

Further, 2 to 3 drops of the composition were melted on a slide glass heated to 120 ° C., and a cover glass was placed on the melt and lightly pressed, and this was pressed with a Nikon microscope (XF-UNR). As a result of observation with transmitted light at
Fine crystals of wax were found.

When the above ink was mounted on an ink jet printer and printing was performed, clear printing was obtained on recording paper without clogging of the printer head. But OHP
The printed matter transmitted light on paper, making it difficult to use as a slide sample.

Comparative Example 2 The room-temperature solid wax used as a vehicle in Comparative Example 2 was paraffin wax (paraffin wax standard product 155, manufactured by Nippon Seiro, melting point 69).
C), methylene bisstearic acid amide (bisamide, Nippon Kasei Co., Ltd., melting point: 143 ° C.), polyamide resin (Versamide 756, manufactured by Henkel Hakusui, softening point: 102-112 ° C.), dye: oil-soluble dye C.I. I. S
olive Black 3 (Oil Black
HBB, manufactured by Orient Industrial Co., Ltd.).

Ink Formula Paraffin Wax Standard 155 49% by weight Bisamide 25% by weight Versamide 756 24% by weight Oil Black HBB 2% by weight The hot-melt ink can be manufactured by the same procedure as in Example 1. Paraffin wax standard product 15
5, bisamide, versamide 756, 70 ℃ ~ 25
Heat and dissolve at a temperature of 0 ° C, preferably about 100 ° C to 200 ° C, and mix OilBlack HBB. This is stirred and mixed with a dissolver at 200 to 10000 RPM, preferably 500 to 5000 RPM. The adjusted ink composition was filtered using a 2 μm mesh filter with a hot filtration device manufactured by Toyo Roshi Kaisha, Ltd.
Obtain the final hot melt ink.

The composition thus prepared was melted on a hot plate heated to 110 ° C., and was then placed on OHP paper (PP-250).
0, manufactured by Sumitomo 3M Co., Ltd.
m), the transparency was clearly increased as compared with the ink of Example 1. It was 12.6% when measured with a HAZE degree meter (manufactured by Suga Test Instruments Co., Ltd.).

Further, 2 to 3 drops of the composition were placed on a slide glass heated to 120 ° C. and melted. A cover glass was placed on the melt and lightly pressed, and this was pressed with a microscope (XF-UNR) manufactured by Nikon Corporation. As a result of observation with transmitted light at
Fine crystals of wax were found.

When the above ink was mounted on an ink jet printer and printing was performed, clear printing was obtained on recording paper without clogging of the printer head. But OHP
Printed matter transmitted light on paper, making it difficult to use as a slide sample.

[0043]

As is apparent from the above description, the hot-melt ink of claim 1 is solid at room temperature,
A wax having a melting point at a temperature of about 50 ° C. or higher, a resin,
It is characterized in that the resin has a softening point lower than the melting point of the wax, including the coloring material. As a result, the crystallization of the wax is not hindered than the fine crystals of the resin, and it is possible to provide an ink that grows larger and has high opacity.
And because the ink itself has almost no transparency,
Optical density on printing paper is improved. When printing is actually performed using this, the printing paper is naturally OH
Good and clear images can be formed on P paper, and a shadow portion (black portion) can be reliably formed on the OHP projection surface.

Further, in the hot-melt ink according to the second aspect, the coloring material is a black dye. For this reason, the color of the image of the ink adhered to the printing paper or the OHP paper becomes black, and a shadow portion (black portion) can be reliably formed even on the OHP projection surface.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an ink manufacturing method according to an embodiment of the present invention.

[Explanation of symbols]

 2 Hi Mic 2095 4 Amide AP- 16 Archon P-708 Oil Black HBB

Claims (2)

[Claims] 1. A hot-melt ink comprising a wax which is solid at normal temperature and has a melting point at a temperature of about 50 ° C. or higher, a resin, and a coloring material. A heat-fusible ink characterized by having a low softening point. 2. The hot-melt ink according to claim 1, wherein the coloring material is a black dye.