JP2000072992A - Hot-melt ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hot-melt ink capable of materializing properties such as water resistance and high printing speed characteristics without selecting the base material of the hot-melt type inkjet system while having sufficient fastness for ordinary office and domestic uses. SOLUTION: A hot-melt ink comprises 5-99 wt.% (meth)acrylic acid based copolymer having a weight average molecular weight of 500-30,000 which is obtained by copolymerizing 10-90 pts.wt. (meth)acrylate ester and 90-10 pts.wt. vinyl ester and/or styrenic monomer. The hot-melt ink is used in a hot-melt inkjet printer which liquefies the solid ink at normal temperatures by heating and jets the liquefied ink on to a material to be recorded to form recorded dots.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hot melt ink, and more particularly, to a hot melt ink for a printer for outputting information equipment such as a computer.

[0002]

2. Description of the Related Art In recent years, computers have rapidly spread, and printers are used for outputting character and image information processed by the computers. There are various types of printers.
There are a thermal transfer method, an ink jet method, a thermal sublimation method, and the like. Of these, the thermal transfer method and the ink jet method are both inexpensive and small, and can perform color printing, and are particularly popular.

The thermal transfer system uses a hot melt ink in the form of a sheet, is melted by a heating head, and is transferred to a recording material. It is easy to reduce the size and is used as a built-in printer such as a word processor. . Recently, a method of controlling the amount of transferred ink by miniaturization of a heating head, heating control, and the like has been found, whereby an image with rich gradation can be obtained. The hot melt ink used here is required to have the ability to dissolve sharply at a specific temperature.

On the other hand, the ink jet system has many advantages, such as being capable of forming a high quality image comparable to a color photograph and being inexpensive. As one of the above-mentioned ink jet systems, a block of a hot melt ink that exists as a solid at normal temperature is liquefied by heating when printing, and the liquid ink is discharged onto a recording material to form recording dots. There is a hot melt type inkjet printer to be formed. The hot-melt ink jet printer can be suitably used not only for output from a computer but also for output from a large printing machine such as a poster or a signboard, a digital camera or a medical device.

At present, the ink mainly used in the ink jet recording system is obtained by dissolving and / or dispersing a coloring material in an aqueous solvent such as water and a small amount of alcohol. Water is non-toxic and does not emit odors, so it can be used safely in offices and homes. However, the water-based inkjet has the following problems. 1) Printing on ordinary paper or cloth causes bleeding of the ink, so that exclusive paper or cloth is required to obtain a high-definition image. 2) Since the ink is easily soluble in water, an image blurs if water adheres to the printed matter. For example, when touched with a sweaty hand, a coloring material adheres to the hand. 3) It is necessary to print in consideration of the time for the recording material to absorb the aqueous solvent, and the printing speed is reduced.

As a method of avoiding these problems, there is a method of performing ink jet recording using hot melt ink. This dissolves the ink that is solid at room temperature with heat,
This is a method of liquefying and spraying this on a recording material. The ink sprayed on the recording material cools and solidifies by adhering to the recording material to form an image. Since the hot-melt type ink is solvent-free, it can be used safely in offices and homes similarly to water-based inks. When a hot melt ink is used, the recording material is not particularly limited, and recording can be performed on any of films, papers, fabrics, and the like without requiring any special treatment, and does not bleed even when wet with water. Further, since the ink is solidified at the same time as it adheres to the recording material, it is not necessary to provide a time interval for absorption by the recording material, and extremely high-speed printing is possible even for a high-definition image.

As such a hot-melt ink material, Japanese Patent Application Laid-Open No. 55-54368 discloses a hot melt ink material having a temperature of 30 to 200 ° C.
An organic compound having a melting point of
JP-A-6-228480 or JP-A-6-228480 proposes a wax compound.

[0008]

SUMMARY OF THE INVENTION Japanese Patent Application Laid-Open No. 55-5436
No. 8 proposes an organic compound having a specific melting point, as described above. However, according to this method, the ink dots of the obtained printed body are solidified forms of an organic low-molecular compound, and are extremely difficult to obtain. When printed paper or the like is bent or rubbed, the image is easily broken or peeled off, so that the printed body lacks robustness and its use for ordinary printing is limited.

Further, Japanese Patent Application Laid-Open No. 58-108271,
In the wax-based compound described in JP-A-6-228480, wax-based materials such as natural wax and modified wax have been proposed.
Peeling has been improved somewhat, but it is still not enough.On the other hand, static electricity is generated in the printing part as a characteristic of wax, not only attracting dust etc., but also using a paper feeder of a copier Paper jams,
After all, the use is limited.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to select a hot-melt ink jet base material while having sufficient robustness for use in general offices and homes. An object of the present invention is to provide a hot melt ink that can realize characteristics such as water resistance, printing speed, and the like.

[0011]

[Means for Solving the Problems] JP-A-55-54368
The lack of image fastness in the publication is due to the lack of cohesion of the low molecular weight material. In order to solve this, it is preferable to use a linear polymer having an appropriate molecular weight.
The cohesive force of a low-molecular material as a solid is caused only by the intermolecular force between molecules, and a strong cohesive force cannot be expected.
In the case of linear polymers, solid solid cohesion is created by interpenetration between molecules, and solid strength that can withstand sufficient use.
In addition, it demonstrates the robustness of printed matter.

On the other hand, JP-A-58-108271 discloses
Alternatively, the wax-based compound disclosed in JP-A-6-228480 is a paraffin-based material that utilizes interpenetration of molecules, but has very little interaction between molecules.
Sufficient cohesion cannot be exhibited, and problems such as generation of static electricity occur. In order to solve this, a linear polymer into which a polar group is appropriately introduced is desirable. In addition, for stabilizing the dispersion of the coloring material, a linear polymer into which a polar group is appropriately introduced is desirable.

The present inventors have conducted intensive studies from the above technical viewpoints and as a result, have solved the above-mentioned problems. That is, the invention according to claim 1 has the (meta)
10 to 90 parts by weight of an acrylic ester, 90 to 10 parts by weight of a vinyl ester and / or a styrene monomer are copolymerized to form a (meth) acrylic acid-based copolymer of 5 to 99 parts.
A hot-melt ink containing at least 1% by weight, wherein the (meth) acrylic acid-based copolymer has a weight average molecular weight of 500 to 3,000.
0 is a hot melt ink.

The above (meth) acrylic acid esters include, for example, (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, n- (meth) acrylate
-Propyl, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n- (meth) acrylate -Hexyl, cyclohexyl (meth) acrylate, (meth)
N-octyl acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate,
Isononyl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, stearyl (meth) acrylate,
Examples include, but are not limited to, dimethylaminoethyl (meth) acrylate, and may be used alone or in combination of two or more.

The vinyl ester monomer is, for example,
Vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl n-caproate, vinyl isocaproate,
Vinyl octanoate, vinyl laurate, vinyl palmitate, vinyl stearate, trimethyl vinyl acetate, vinyl chloroacetate, vinyl trichloroacetate, vinyl trifluoroacetate, vinyl benzoate, vinyl pivalate, and the like. Among them, in particular, vinyl acetate is widely used industrially and is preferably used.

The styrene monomer includes styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, p-ethylstyrene. , P-isopropylstyrene, p-chloromethylstyrene, p- (2-chloroethyl) styrene and the like. Among them, styrene is widely used industrially and is preferably used.

These vinyl esters and styrene monomers may be used alone or in combination of two or more.

Such (meth) acrylates,
By appropriately combining a vinyl ester and / or a styrene monomer, an ink capable of obtaining a printed matter having sufficient fastness can be obtained.

As the (meth) acrylic acid ester, n-butyl acrylate, 2-
Particularly preferred is at least one of ethylhexyl acrylate, isooctyl acrylate, n-octyl acrylate and isononyl acrylate. As the vinyl ester and / or styrene monomer, styrene is particularly preferred as described in claim 7. preferable.

In the (meth) acrylic acid copolymer, these monomers are added in an amount of 10 to 90 parts by weight of (meth) acrylic acid ester and 90 to 10 parts by weight of vinyl ester and / or styrene monomer. Limited.
This results in a copolymer having the desired performance. When one of the monomers exceeds 90 parts by weight, the performance is the same as that of each homopolymer, and it becomes difficult to adjust melting properties, solid cohesion, flexibility, and the like to desired performances.

The hot melt ink of the present invention is suitable for use in an ink jet printer, and contains 5 to 99% by weight, more preferably 30 to 97% by weight of a (meth) acrylic acid-based polymer. Here, if the content of the (meth) acrylic acid-based polymer is less than 5% by weight and the remaining components are composed of an organic low molecular weight compound, wax, or the like, there is a conventional problem.
It is difficult to completely eliminate the robustness of printing.
On the other hand, a hot-melt ink cannot obtain a required color density unless it contains at least 1% by weight or more of a dye or pigment, so that more than 99% by weight of a (meth) acrylic acid-based polymer is used. It is difficult to obtain a high-color-forming image with a hot-melt ink containing the same.

The weight average molecular weight of the (meth) acrylic acid polymer used in the present invention is limited to 500 to 30,000. Preferably, depending on the composition of the monomer,
Usually, it is 1,000 to 10,000. The weight average molecular weight can be measured by a known method, but if a general gel permeation chromatograph (GPC) is used, the weight average molecular weight in terms of styrene can be easily determined. When the weight average molecular weight is less than 500,
It does not become solid at room temperature, which makes it difficult to handle the ink and also makes the printed matter sticky.
If it becomes larger, not only the melting temperature becomes high, and a large amount of heat energy is required for melting, but also the viscosity becomes high even after melting, making it difficult to cope with high-speed printing.

The hot melt ink containing the (meth) acrylic acid polymer of the present invention is obtained by mixing the (meth) acrylic acid polymer with a coloring material. As the coloring material, any known dyes and pigments can be used without any problem. Regarding pigments, those generally used in printing can be used irrespective of inorganic pigments and organic pigments. The following are examples of pigments, but pigments that can be used in the present invention are not limited thereto.

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, sulene pigments, perylene pigments,
Perinone pigments, thioindigo pigments, quinophthalone pigments, metal complex pigments, and the like. These may be used alone or as a mixture of a plurality of pigments.

Further, examples of the dye include the following, but the dye usable in the present invention is not limited thereto. Azo dyes, metal complex dyes,
Naphthol dye, anthraquinone dye, indigo dye,
Carbonium dye, quinone imine dye, xanthene dye, cyanine dye, quinoline dye, nitro dye, nitroso dye, benzoquinone dye, naphthoquinone dye, phthalocyanine dye, metal phthalocyanine dye, and the like. These may be used alone or as a mixture of a plurality of dyes.

These pigments and dyes are desirably contained in the range of 1 to 10% by weight based on the whole ink. 1
If the amount is less than 10% by weight, a sufficient color density cannot be obtained, and if the amount is more than 10% by weight, not only the physical properties of the ink discharged from the ink jet recording apparatus are affected, but also the ink becomes expensive.

In addition, a wax at room temperature may be added to adjust the melting point or melt viscosity. As wax, petroleum waxes such as paraffin wax,
Vegetable waxes such as candelilla wax and carnauba wax, animal waxes such as beeswax, synthetic waxes such as polyethylene wax, mineral waxes, and the like, and modified ones thereof can be used. In addition, higher fatty acids and higher alcohols
Conventionally known waxes are not particularly limited, and can be used. These waxes may be used alone, or 2
More than one kind may be mixed and used.

These waxes can be appropriately used in such an amount that the fastness of the printed matter is not lost.

As the viscosity adjusting material, an existing synthetic resin or natural resin may be added. Further, a surfactant may be used as a dispersion stabilizer, and a radical scavenger, an ultraviolet absorber, an antioxidant, or the like may be used as a stabilizer, or a plasticizer may be used in combination.

In the production of the hot melt ink of the present invention, the above-mentioned (meth) acrylic acid-based polymer, coloring material and other additives can be mixed by a known method. Examples thereof include a method using a media mill or the like and a method of mixing with a three-roll mill. Further, pressure may be applied as needed. After mixing, it is preferable that the obtained mixture is filtered and used. The resulting mixture is shaped into a shape that is compatible with the predetermined ink feeder of the printer. As a molding method, a known method such as casting, injection molding, or coating can be used.

The hot melt ink of the present invention is described in claim 2.
As described in, the ink which is solid at room temperature is liquefied by heating, and the liquid ink is discharged onto a recording material to form recording dots. This is particularly preferable because it can ensure the degree of freedom, water resistance, and high-speed printing.

In the hot melt ink according to the present invention, as described in claim 3, the molecular weight distribution (weight average molecular weight / number average molecular weight) of the (meth) acrylic copolymer is 1.
It is preferably from 0.5 to 1.9.

As described above, the hot melt ink can be suitably used in the ink jet system. In this ink jet printer, the ink is dissolved, the ink is discharged from the nozzles in a molten state, and adhered to the recording material. . Therefore, when the hot melt ink is melted, the thermal property of the ink is a major performance point.
It is desirable for the ink to exhibit as sharp a dissolution behavior as possible at a specific temperature, and it is desirable that the ink be free of volatiles from the viewpoint of safety and prevention of nozzle clogging. Generally, when a (meth) acrylic acid-based copolymer is polymerized by ordinary radical polymerization, it shows a relatively wide molecular weight distribution (weight average molecular weight / number average molecular weight; usually 2 or more) and has a high molecular weight. To low molecular weight. With such a distribution of molecular weights, those having a high molecular weight are difficult to dissolve even at high temperatures, and also increase the viscosity of the molten ink more than necessary.On the other hand, those having a low molecular weight have a hot melt due to a plasticizing effect. In the temperature range where the ink or printed matter becomes sticky or dissolves the entire ink,
Volatilization gives off odors and harmful substances, and in the case of an ink jet system in particular, changes in the components of the ink make it impossible to stably eject the ink and cause nozzle clogging. Therefore, the molecular weight distribution is 1.05 to
It is particularly preferred that it is in the range of 1.9. Here, it is very difficult to reduce the molecular weight distribution to less than 1.05, so that the cost is high and the hot melt ink is expensive. On the other hand, when the molecular weight distribution is larger than 1.9, there is no difference from the molecular weight distribution obtained by general radical polymerization, and the possibility of occurrence of the above-mentioned problem increases.

As a method for performing such polymerization in which the molecular weight is controlled, a so-called living polymer polymerization method can be used, and examples thereof include a living anion polymerization method, a living radical polymerization method, a living cationic polymerization method, Coordination anion polymerization method may be mentioned.

In order to obtain such a polymer having a controlled molecular weight distribution, the anionic polymerization method is preferable. Hereinafter, the anionic polymerization method will be described.

As the anionic polymerization initiator, known anionic polymerization initiators can be used. The initiator used may be either a monofunctional or bifunctional initiator. Examples of monofunctional initiators include n-butyl lithium, sec-butyl lithium, tert-butyl lithium, cumyl potassium, cumyl cesium, 1,1-diphenylhexyl lithium, fluorenyl lithium, sodium (α-methylstyrene oligomer) And the like. Examples of the bifunctional initiator include lithium naphthalene, sodium naphthalene, potassium naphthalene, disodium (α-methylstyrene oligomer), and dipotassium (α-methylstyrene oligomer).

The anionic polymerization is carried out in an inert gas atmosphere or under reduced pressure in a solvent inert to the polymerization reaction.
The reaction is performed at a temperature of 50C to 50C, preferably -100C to 40C for 1 minute to 100 hours. Examples of the solvent include tetrahydrofuran (THF), toluene, cyclohexane, benzene, xylene, diethyl ether,
Examples thereof include dimethoxyethane and dioxane, and one or more of these may be used.

In the polymerization, tertiary amines such as tetramethylethylenediamine, dipiperidinoethane, triethylamine and N-methylpyrrolidine, 12-crown-4 and 15-crown- are used as additives in order to control the activity of the growth terminal. One or more kinds of crown ethers such as 5 and salts such as lithium chloride, sodium chloride, potassium chloride and cesium chloride can be used. It is preferable to add 1 to 10 molar equivalents of these additives to the growth terminal. In addition to the above, by adding 1,1-diphenylethylene in an amount of 1 to 1.2 mol equivalent at the growth end, it is possible to suppress a side reaction to the carbonyl group of the (meth) acrylate at the growth end, Living property of polymerization can be improved.

When terminating the polymerization, for example, a proton donor such as alcohol such as methanol, ethanol or phenol or water or trimethylsilyl chloride can be reacted with the growth terminal to terminate the polymerization.

The amount of the anionic polymerization initiator was 1 M
0.001 to 0.5M, preferably 0.002
~ 0.3M. If the amount is too small, the polymerization rate is low and the weight average molecular weight is more than 30,000, which is not preferable. When used in excess, the weight average molecular weight becomes 50
It is not preferable because it becomes smaller than 0.

Unlike the anionic polymerization method, the living radical polymerization method does not require strict dehydration and purification of a polymerization solvent and a monomer, and can be used for bulk polymerization. It is a polymerization method that has been used. In the living radical polymerization method, the iniferter method, 2,
2,6,6-tetramethyl-1-piperidiniloxy (T
EMPO), a method using an organometallic complex,
Claims include a method using an iodine compound.
In any one of the inventions of (1) to (3), any of them may be used. However, as described in claim 5, in particular, the polymerization can be performed under the control of the molecular weight and under mild conditions, and the purification of the polymer is relatively easy. The method using an iodine compound is the most practical.

The iodine compound used in the present invention has at least one of a carbon-iodine bond, a hydrogen-iodine bond and a halogen-iodine bond, as described in claim 6. Is preferred.

Examples of the compound having a carbon-iodine bond include alkyl iodide, perfluoroalkyl iodide, an adduct of hydrogen iodide and an alkene, and phenyl iodide. Specifically, examples of the alkyl iodide include iodomethane, iodoethane, iodopropane, iodobutane, diiodomethane, 1,2-diiodoethane, iodoform, chloroiodomethane, iodoacetonitrile, iodoacetic acid and the like.

Examples of perfluoroalkyl iodide include iodoperfluoropropane, 1-iodoperfluorohexane, 1-iodoperfluorooctane, 1,2-diiodoperfluoroethane, 1,4-diiodoperfluorobutane, 1,6 diiodoperfluorohexane and the like.

Examples of the alkene used in the adduct of hydrogen iodide and the alkene include vinyl ester monomers such as vinyl acetate, various vinyl ether monomers such as isobutyl vinyl ether, and styrene monomers. Phenyl iodide includes Examples thereof include iodobenzene and 2-iodoethylbenzene. Examples of the synthesis of an adduct of hydrogen iodide and an alkene include a method of mixing anhydrous hydrogen iodide with an alkene at a low temperature.

The compound having a hydrogen-iodine bond includes, for example, hydrogen iodide. The above halogen-
Examples of the compound having an iodine bond include iodine, iodine monochloride, iodine trichloride, and iodine monobromide.

Examples of preferably used iodine compounds include alkyl iodides such as iodoform, diiodomethane, iodoacetonitrile, 1-iodoperfluorohexane, 1,4-diiodoperfluorobutane, 1,6
Perfluoroalkyl iodide such as -diiodoperfluorohexane, an adduct of hydrogen iodide and an alkene, hydrogen iodide and the like. Further, when iodoform is used, one molecule of iodoform added to the polymerization is converted into one polymer.
This is particularly preferable because the calculated value of the number average molecular weight, which is assumed to form a molecule, and the measured value most accurately match. As the iodine compound, one of the above may be used alone, or a mixture of two or more thereof may be used.

The molecular weight distribution (Mw / Mn) of the (meth) acrylic acid-based copolymer obtained by polymerization in the presence of an iodine compound is higher than that obtained by conventional ordinary radical polymerization without addition of an iodine compound. Is controlled,
1.05 to 1.9.

The amount of the iodine compound can be appropriately determined with respect to the desired molecular weight of the polymer. If the amount is too small, the structure of the polymer cannot be controlled, and if it is too large, the polymer cannot be obtained. Therefore, 1
It is preferable to add 0.001 to 0.5M to M. In particular, 0.002 to 1 M of monomer
It is preferable to add at a rate of 0.3M.

The method of addition is not particularly limited, but is preferably added to the polymerization system before the start of polymerization, from the viewpoint of controlling the molecular weight distribution and simplifying the operation.

When polymerizing in the presence of an iodine compound,
The weight average molecular weight of the (meth) acrylic acid-based copolymer obtained by the concentration of the iodine compound can be adjusted to a desired value, and a polymer having a low molecular weight and a narrow molecular weight distribution can be easily obtained.

The radical polymerization used in the present invention includes the use of a usual radical polymerization initiator, the use of a photopolymerization initiator and irradiation with light, irradiation with radiation, laser light, light, and the like, heating, and the like.

In particular, it is preferable to use a radical polymerization initiator industrially. The type of the radical polymerization initiator is such that it can generate a radical and react with a vinyl ester or an iodine compound to cause polymerization. There is no particular limitation, and the compound is selected from compounds that generate a radical by the action of heat, light, radiation, an oxidation-reduction chemical reaction, or the like. Specific examples include azo compounds, organic peroxides, inorganic peroxides, organometallic compounds, and photopolymerization initiators. More specifically, azo compounds such as azobisisobutyronitrile (AIBN), azobisisobutyric acid ester and hyponitrite, benzoyl peroxide (BPO), lauroyl peroxide,
Organic peroxides such as dicumyl peroxide and dibenzoyl peroxide; inorganic peroxides such as potassium persulfate and ammonium persulfate; hydrogen peroxide-ferrous iron; BPO
Redox initiators such as dimethylaniline-based and cerium (IV) salt-alcohol-based. Especially AI
BN and BPO are preferably used.

In the case of photopolymerization, an acetophenone-based, benzoin ether-based, ketal-based photopolymerization initiator may be added.

The radical generating method and the radical polymerization initiator may be used singly or in combination of two or more as long as the interaction does not adversely affect the progress of polymerization. Further, a combination in which the polymerization is advanced to some extent by the action of heat and then the polymerization is completed by light may be used.

The amount of the radical polymerization initiator is not particularly limited as long as the polymerization can be caused, but it is preferably in the range of 0.02 to 20 M with respect to 1 M of the iodine compound used, and the amount with respect to 1 M of the monomer. 0.0005-1
M is preferred. If the amount is too small, the polymerization is slowed down and the polymerization rate is low, which is not industrially advantageous. Also,
If used in excess, it may be difficult to control the reaction, which is not preferred. A more preferred amount of the radical polymerization initiator is 0.05 to 10 with respect to 1M of the iodine compound.
M, 0.001 to 0.5 M per 1 M of monomer
It is. A particularly preferred amount of the radical polymerization initiator is in the range of 0.1 to 5M based on 1M of the iodine compound.

The preferred range of the polymerization temperature varies depending on the type of the radical polymerization reaction, and is not particularly limited. However, the polymerization is generally carried out at a temperature of about -30 to 120 ° C. Further, the preferable temperature range is 0 to 100.
° C. The reaction pressure is usually normal pressure, but it is also possible to increase the pressure.

The polymerization method used in the present invention is not limited to any of those conventionally used, and bulk, solution, suspension, emulsion polymerization and the like are used. In particular, bulk polymerization is preferably used from the viewpoint of suppressing chain transfer and obtaining a better controlled polymer. Further, continuous polymerization using an extruder can also be used. Further, as a solvent for solution polymerization, a commonly used solvent such as alcohol, toluene and benzene can be used.

From the viewpoint of improving the stability of the polymer used in the present invention, by adding methanol, ammoniacal methanol, lithium borohydride or the like to the polymerization system at the time of stopping the polymerization, iodine existing at the growing terminal of the polymer is added. May be desorbed. In addition, in the presence of isopentane or the like, the obtained polymer is irradiated with ultraviolet light,
Iodine may be stabilized with hydrogen.

[0060]

The hot melt ink according to claim 1 is obtained by copolymerizing 10 to 90 parts by weight of a (meth) acrylate, 90 to 10 parts by weight of a vinyl ester and / or a styrene monomer. 5 to 5
A hot melt ink containing 99% by weight, comprising (meth)
The weight average molecular weight of the acrylic acid copolymer is 500 to 30
000, it has appropriate polarity, flexibility and heat melting properties. Therefore, when the hot-melt ink of the present invention is used in a hot-melt ink-jet printer, it is possible to secure the flexibility of the substrate, the water resistance of the ink, and the high-speed printability while securing the image fastness, which has been a problem in the past. Can be.

The hot melt ink according to claim 2 is a hot melt ink-jet method in which a solid ink at normal temperature is liquefied by heating, and the liquefied ink is discharged onto a recording material to form recording dots. Since the hot melt ink according to claim 1 is used for a printer, the hot melt ink jet printer using the hot melt ink ensures the flexibility of the base material, the water resistance of the ink, and the high-speed printability. In addition, it is possible to secure image robustness, which has been a problem in the related art.

The hot melt ink according to claim 3 is
Since the molecular weight distribution (weight-average molecular weight / number-average molecular weight) of the (meth) acrylic acid-based copolymer is 1.05 to 1.9, the melting point becomes sharper, and at the same time, the low-molecular-weight material is not volatilized, which is safe. This contributes to the realization of efficient printing.

The hot melt ink according to claim 4 is
Since the (meth) acrylic acid-based copolymer is polymerized by anionic polymerization, the molecular weight and molecular weight distribution are controlled, so that a sharper melting point is obtained, and at the same time, low-molecular-weight substances are not volatilized, which is safe. This contributes to efficient printing.

The hot melt ink according to claim 5 is
Since the (meth) acrylic acid-based copolymer is obtained by polymerizing (meth) acrylic acid ester, vinyl ester and / or styrene-based monomer in the presence of an iodine compound, the molecular weight and the molecular weight distribution are A controlled polymer is more easily obtained, is inexpensive, has a sharper melting point, and has no volatilization of low molecular weight substances, which contributes to realization of safe and efficient printing.

In the hot melt ink according to the sixth aspect, the iodine compound has at least one of a carbon-iodine bond, a hydrogen-iodine bond and a halogen-iodine bond. Is more easily obtained, is inexpensive,
At the same time as having a sharper melting point, volatilization of low molecular weight substances is also eliminated, which contributes to realization of safe and efficient printing.

The hot melt ink according to claim 7 is the one in which the vinyl ester and / or styrene monomer in any one of claims 1 to 6 is specifically defined as styrene. It can contribute to the realization of useful printing described in the invention.

The hot melt ink according to the eighth aspect is the one in which the (meth) acrylate in the invention according to any one of the first to seventh aspects is specifically defined.
This can contribute to the realization of useful printing described in the invention of the seventh aspect.

[0068]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments, but the present invention is not limited thereto. Unless otherwise noted, monomers, solvents, etc. were used after removing the polymerization inhibitor and impurities by distillation and purification, and then subjected to deoxygenation treatment.

Measurement method of polymerization rate The polymerization rate was measured by gas chromatography using n-heptane as an internal standard (gas chromatography: manufactured by Shimadzu Corporation, column: PEG 1500).

Measurement method of molecular weight The number average molecular weight (Mn) and weight average molecular weight (Mw) were measured in terms of polystyrene by gel permeation chromatography (GPC) (GPC: LS8000 system, manufactured by Tosoh Corporation, column: Showa) Denko, polystyrene gel KF-802, 803, 804, solvent:
Chloroform, flow rate: 1 ml / min). The ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn) was defined as a molecular weight distribution (Mw / Mn).

Further, a hot melt ink jet printer (manufactured by Tektronix; trade name: Phaser 340) was used for evaluation of the printed material, but a spray was easily applied to a hand gun type hot melt applicator (manufactured by Suntool). A discharge port of the type was attached, sprayed on plain paper, and evaluation was performed using the obtained ink adhering body.

The evaluation was performed on the following items. 1) Bending resistance: The printed matter was bent, and the occurrence of cracks was visually evaluated. Judgment criteria 割 れ: No cracks occurred X: Cracks occurred 2) Scuff resistance: Plain paper was placed on printed matter, 100 g / 1
Rubbing was performed 10 times with a pressure of cmφ, and it was visually confirmed whether the printed portion did not peel off or color did not appear on the stacked plain paper. 3) Suitability for copy paper feeding: The printed plain paper was attached to a paper feeding machine of a copying machine, and it was evaluated whether paper feeding was possible. Judgment criteria ○: There is no problem in paper feeding ×: Paper feeding is not possible

Example 1 1.6 g of AIBN, 4.0 g of iodoform, 80 g of styrene, and 20 g of 2-ethylhexyl acrylate were placed in a 500 ml flask purged with nitrogen.
g, 5.0 ml of n-heptane was charged, the container was sealed,
After uniform mixing, the mixture was heated to 80 ° C. to initiate polymerization. After polymerization for 3 hours, the temperature was lowered to 0 ° C. to terminate the polymerization. The polymerization rate was 97% as determined by gas chromatography. The polymer solution was poured into a large amount of methanol to precipitate the product. After drying, this was purified by reprecipitation with methanol and dried under vacuum to obtain a polymer.
This was dissolved in toluene under a nitrogen atmosphere, and 1.5 g of sodium hydroxide dissolved in 50 ml of water was added.
The terminal iodine was removed over time. After the completion of the reaction, the obtained reaction solution was washed with water, and the solvent toluene was vacuum-dried at 80 ° C. for 5 hours to obtain a styrene / 2-ethylhexyl acrylate copolymer. When the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) were determined by GPC, Mn = 9500 and Mw / Mn = 1.50.

50 parts by weight of this copolymer, 45 parts by weight of paraffin wax 115 (manufactured by Nippon Seiwa) and 5 parts by weight of carbon black (MA-7, manufactured by Mitsubishi Chemical Corporation) were mixed with 140 parts by weight.
The mixture was put into a steel container heated in an oil bath and stirred with a dissolver at 4000 rpm for 10 minutes. The obtained mixture was cooled and solidified as it was, poured into a hot melt applicator, heated to 120 ° C., and sprayed on plain paper. Using the obtained ink-attached body, bending resistance, rubbing resistance and suitability for copy paper feeding were evaluated, and the results are shown in Table 1.

Example 2 A 500 ml flask purged with nitrogen was charged with 3.5 g of AIBN, 11.0 g of 1,6-diiodoperfluorohexane, 70 g of styrene, 30 g of n-butyl acrylate, and 5.0 ml of n-heptane. After the container was sealed and uniformly mixed, the mixture was heated to 60 ° C. to start polymerization. After 10 hours of polymerization, the temperature was reduced to 0
C. to terminate the polymerization. The polymerization rate was 97% as determined by gas chromatography. The polymer solution was poured into a large amount of methanol to precipitate the product.
After drying, this was purified by reprecipitation with methanol and dried under vacuum to obtain a polymer. This was dissolved in toluene under a nitrogen atmosphere, and 6.0 g of sodium sulfite dissolved in 15 ml of water.
Was added, and the terminal iodine was removed at 70 ° C. for 6 hours while irradiating with ultraviolet rays. After the completion of the reaction, the obtained reaction solution was washed with water, and the solvent toluene was dried under vacuum at 80 ° C. for 5 hours to obtain a styrene / n-butyl acrylate copolymer. When the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) were determined by GPC, Mn = 510
0, Mw / Mn = 1.41.

70 parts by weight of this copolymer, 25 parts by weight of paraffin wax 115 (manufactured by Nippon Seiwa Co., Ltd.) and 5 parts by weight of carbon black (MA-7, manufactured by Mitsubishi Chemical Corporation) were mixed with 140 parts by weight.
The mixture was put into a steel container heated in an oil bath and stirred with a dissolver at 4000 rpm for 10 minutes. The obtained mixture was cooled and solidified as it was, poured into a hot melt applicator, heated to 120 ° C., and sprayed on plain paper. Using the obtained ink-attached body, bending resistance, rubbing resistance and suitability for copy paper feeding were evaluated, and the results are shown in Table 1.

Example 3 1000 m purged with argon
500 ml of THF dried and distilled with sodium / potassium alloy, 80 g of styrene dried with calcium halide and molecular sieve,
After charging 20 g of ethylhexyl acrylate and mixing uniformly, the mixture was cooled to -78 ° C. While stirring the solution, 18 ml of a 2.0 M solution of sec-butyllithium in cyclohexane was added under an argon flow to initiate polymerization.
After polymerization for 3 hours, methanol was added to terminate the polymerization. When unreacted monomers in the reaction solution were measured by gas chromatography, neither styrene nor 2-ethylhexyl acrylate could be detected, and it was confirmed that the polymerization conversion was almost 100%. After drying the polymer solution, the polymer solution is washed twice with methanol, dried under vacuum, and dried with styrene /
A 2-ethylhexyl acrylate copolymer was obtained. The number average molecular weight (Mn) and molecular weight distribution (M
w / Mn), Mn = 2900, Mw /
Mn = 1.35.

95 parts by weight of this copolymer and 5 parts by weight of carbon black (MA-7, manufactured by Mitsubishi Chemical Corporation) were mixed at 140 ° C.
The mixture was put into a steel container heated in an oil bath, and stirred with a dissolver at 4000 rpm for 10 minutes. The obtained mixture was cooled and solidified as it was, poured into a hot melt applicator, heated to 120 ° C., and sprayed on plain paper. Using the obtained ink-attached body, bending resistance, rubbing resistance and suitability for copy paper feeding were evaluated, and the results are shown in Table 1.

(Comparative Example 1) An ordinary document was output on plain paper in black using a solid inkjet printer Phaser340 manufactured by Tektronix. This hot melt ink is composed of about 70% of wax and 30% of vegetable resin. Using the obtained ink-attached body, bending resistance, rubbing resistance and suitability for copy paper feeding were evaluated, and the results are shown in Table 1.

[0080]

[Table 1]

[0081]

The constitution of the hot melt ink of the present invention is as described above, and is not limited to a recording material, and is suitable for an ink jet printer using a hot melt ink which has many advantages such as good water resistance and high speed printing. By using the hot melt ink of the present invention, the robustness of the ink attached to the printed matter and adaptability to a copy paper feeder can be significantly improved. By using the hot melt ink of the present invention, a hot melt ink type ink jet printer can be widely used not only for design but also for general offices and posters. On the other hand, in printers using hot melt ink, such as a thermal transfer printer,
By using the hot melt ink of the present invention, it is possible to print efficiently and at high speed with less heat energy.

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Claims (8)

[Claims] 1. A (meth) acrylate ester 10 to 90.
A hot melt ink containing 5 to 99% by weight of a (meth) acrylic acid-based copolymer obtained by copolymerizing 90 to 10 parts by weight of a vinyl ester and / or styrene-based monomer, wherein the (meth) acrylic acid A hot melt ink, wherein the weight average molecular weight of the copolymer is from 500 to 30,000. 2. A hot-melt type ink jet printer which forms a recording dot by liquefying an ink which is solid at normal temperature by heating and discharging the liquefied ink onto a recording material. The hot melt ink according to claim 1, wherein 3. The molecular weight distribution (weight average molecular weight / number average molecular weight) of the (meth) acrylic acid copolymer is from 1.05 to 1.05.
3. The hot melt ink according to claim 1, wherein the hot melt ink is 1.9. 4. The hot melt ink according to claim 1, wherein the (meth) acrylic acid copolymer is polymerized by anionic polymerization. 5. A (meth) acrylic acid copolymer obtained by polymerizing (meth) acrylic acid ester, vinyl ester and / or styrene monomer in the presence of an iodine compound. The hot melt ink according to any one of claims 1 to 3, wherein the hot melt ink is a copolymer. 6. The hot melt ink according to claim 5, wherein the iodine compound has at least one of a carbon-iodine bond, a hydrogen-iodine bond, and a halogen-iodine bond. 7. The method according to claim 1, wherein the vinyl ester and / or the styrene monomer is styrene.
The hot melt ink according to any one of the above. 8. The method according to claim 1, wherein the (meth) acrylate is n-butyl acrylate, 2-ethylhexyl acrylate,
The hot melt ink according to any one of claims 1 to 7, wherein the ink is at least one of isooctyl acrylate, n-octyl acrylate, and isononyl acrylate.