KR20160121687A - Ultraviolet curable ink composition adapted picture printing - Google Patents

Abstract

The present invention relates to an ultraviolet ray curable ink composition suitable for photographic printing. It improves curability and reduces errors in quality depending on the thickness of a material or a printed material, improves adhesion or adhesion, improves durability according to changes in material behavior, To an ultraviolet curable ink composition having less irritation. An ultraviolet curable ink composition comprising an oligomer end-modified with an unsaturated group, a photopolymerizable monomer, a photopolymerization initiator, a gelling agent, and a coloring pigment, wherein 100 parts by weight of the oligomer terminated with the unsaturated group, Based ink composition according to the present invention.

Description

[0001] The present invention relates to an ultraviolet curable ink composition suitable for photo printing,

The present invention relates to an ultraviolet ray curable ink composition suitable for photographic printing. It improves curability and reduces errors in quality depending on the thickness of a material or a printed material, improves adhesion or adhesion, improves durability according to changes in material behavior, To an ultraviolet curable ink composition having less irritation.

In general, phase change inks are forms in which liquid droplets are ejected from the printing apparatus and the ink droplets come into contact with the surface of the material so that the droplets solidify rapidly to form a predetermined pattern of solidified ink droplets. One type of phase change ink is a curable ink, which can be divided into a thermosetting type and a light curing type, and an ultraviolet (UV) curing ink belongs to a light curing type.

UV curable inks are inks that cure in seconds, resulting from the photochemical reaction of ultraviolet energy. Generally at least one curable monomer, a colorant, a gelling agent, a crosslinking agent, a photoinitiator and the like. The ultraviolet curing ink has many advantages such as instant drying, low-temperature high-speed productivity, solvent-free, and pollution-free, compared with conventional solvent-based ink, and is now widely used. However, it is difficult to obtain relatively desirable coating characteristics and is mainly used for relatively hard materials. In some cases, depending on the material and film thickness, partial hardening problems or soft materials are difficult to be adhered due to poor adhesion and durability. There are many cases where it is necessary. In addition, there is no problem due to the ingestion of harmful substances, but skin irritation may occur due to the use of a monomer having a low molecular weight.

On the other hand, unlike ultraviolet curable resins used in PCBs and various displays, various types of pigments are included in printing in the form of images as shown in the photograph. The presence of such pigments provides an obstacle to the curing action because the photoinitiator absorbs a range of UVs that must be absorbed to form the initiating radical. The pigment concentration can be diluted to reduce interference due to UV absorption of the pigment, and this dilution causes loss of saturation. This problem poses a problem that the use of ultraviolet curable inks may be limited in printing images. However, since the material used for printing images such as photographs is expanded to a hard material, it is still a material based on paper or processed paper, or a textile, leather or artificial leather material is used. Therefore, It is necessary to have a resilience so that the formed shape is not broken or broken. Further, it is necessary to further reduce hardness and adhesiveness to reduce the quality error, and it is necessary to further lower skin irritation because it is a product which may have skin contact. In addition, storage stability is important in view of the characteristics of a printing ink. In some cases, not only light but also heat may cause radical polymerization of monomers and oligomers. The maintenance of a certain viscosity is important due to the nature of the printing ink, but excessive use of the gelling agent also lowers the storage stability, and therefore solving the problem is also an important problem.

The present invention has been made to solve the above problems, and it is an object of the present invention to prevent the curing action from being weakened by the addition of a coloring pigment so as to provide a sufficient coloring expression, To provide a suitable ink.

The present invention provides an ultraviolet curable ink composition comprising an oligomer end-modified with an unsaturated group, a photopolymerizable monomer, a photopolymerization initiator, a gelling agent, and a coloring pigment, wherein 100 parts by weight of the oligomer end- And 10 to 50 parts by weight of the nano-clay.

The layer-separated nano-clay and the coloring pigment are preferably added by kneading so that the coloring pigment is contained in the card-gathering structure of the layer-separated nano clay, and the oligomer end-modified with the unsaturated group is an ester acrylate and an epoxy acrylate Based acrylic oligomer, and the photopolymerizable monomer is preferably an acrylic monomer.

It is also preferable that the gelling agent is a composite gelling agent comprising a curable polyamide and a curable epoxy acrylate.

Hereinafter, the present invention will be described in detail.

The oligomer end-modified with an unsaturated group used in the present invention uses an ultraviolet curing resin as a photopolymerizable oligomer. For example, an unsaturated polyester resin, a polyfunctional acrylate resin, an epoxy acrylic resin, an epoxy acrylate resin, a urethane, a urethane acrylate, and the like can be used alone or in combination as a photopolymerizable oligomer and a number average molecular weight of 500 to 5000 . More preferably, the oligomers modified end-to-end with an unsaturated group may comprise a modified epoxy acrylate oligomer having a number average molecular weight of 500 to 1500 and an unsaturated ester acrylate oligomer having a number average molecular weight of 1000 to 3000. In the present invention, an epoxy acrylate oligomer end-modified with an unsaturated group has an effect of improving the curing rate. Examples include commercially available Ebecryl 600, Ebecryl 3700, Ebecryl 3701, Ebecryl 3702 from SK Cytec, PHOTOMETER 3016-LT from Cognis, PHOTOMETER 3016, and the like. Further, in the present invention, the unsaturated ester acrylate oligomer is easy to control the viscosity, and the leveling effect of the surface of the cured product after the ultraviolet curing is prominent. For example, commercially available Ebecryl 830 from SK Cytec, and PHOTOMETER 5010 from Cognis.

The photopolymerizable acrylic monomer in the composition of the present invention functions as a reactive diluent. In the conventional ultraviolet curable ink composition, an organic solvent or a reactive monomer is used as a diluent, but in the present invention, it is most preferable to use a reactive monomer, that is, an acrylic monomer, in order to achieve desired properties (for example, resistance to scratching). Acrylic monomers that can be used in the present invention include aliphatic acrylates such as lauryl acrylate and stearyl acrylate; Diacrylates of glycols such as propylene glycol diacrylate and polypropylene glycol diacrylate; Diacrylates of hydroxylated alcohols such as 1,4-butanediol diacrylate, neopentyl glycol diacrylate, dipropylene glycol diacrylate and triethylene glycol; And trifunctional triacrylates such as trimethylolpropane triacrylate or glyceryl triacrylate. Preferably, trifunctional triacrylate is used, more preferably, trimethylolpropane triacrylate is used. Such trifunctional triacrylate is preferably an alkoxylated acrylate such as ethoxylated trimethylolpropane triacrylate Rate and the like.

The photopolymerization initiator used in the ink composition of the present invention has a function of curing the composition of the present invention when exposed to ultraviolet rays and it is preferable to use a free radical photopolymerization initiator since the material to be polymerized is an acrylate material. Examples of the free radical type photopolymerization initiator include a carbonyl compound, a sulfur compound, an azo compound and an organic peroxide, and more preferably a carbonyl compound such as a ketone, acetophenol, benzophenone and derivatives thereof. Examples of the carbonyl photopolymerization initiator include methyl ethyl ketone; Benzophenone; Benzyl dimethyl ketal; 1-hydroxycyclohexyl phenyl ketone; Diethoxyacetophenone; 2-methyl-1- (methylethiophenyl) -2- (4-morpholinyl) -1-propanone; 2-benzyl-2-N, N-dimethylamino-1,4 (4-morpholinophenyl) -1-butanone; 2,2-dimethoxy-2-phenylacetophenone; 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1-one; 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-methylpropyl) ketone; Bis (2,6-dimethoxybenzoyl) -2-4-4-trimethylpentylphosphine oxide and 2-hydroxy-2-methyl-1-phenyl-propan-1-one. . In the composition of the present invention, it is most preferable to use 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator.

On the other hand, a gelling agent suitable for use in the ink composition includes a curable gelling agent including a curable amide, a curable polyamide-epoxy acrylate component and a polyamide component, and the curable composite gelling agent includes a curable epoxy resin and a polyamide resin , Mixtures thereof, and the like. Preferably, it is a composite gellant comprising a curable polyamide and a curable epoxy acrylate. This takes into account the compatibility of the photopolymerizable resin with that used as a reactive diluent. If a gelling agent is included in the composition, the viscosity of the composition rapidly increases when the composition is cooled after application, so that the composition can be applied to one or more portions of the substrate and / or one or more portions of the preformed image on the substrate, without undue penetration into the substrate To be applied to the same substrate. If liquid is excessively penetrated into a porous substrate such as paper, substrate opacity can be undesirably reduced.

The ink composition may optionally contain a coloring agent. When the colorant is dissolved or dispersed in the ink vehicle, a suitable effective colorant may be used in the ink composition, including any of dyes, pigments, mixtures thereof, and the like. In certain embodiments, pigments that are generally less expensive and harder than dyes may be included. The color of the multiple dyes may be altered during the curing step by a polymerization process that results from attack of these molecular structures, perhaps by free radicals. The composition may be used in combination with conventional ink-coloring materials such as color index (C.I.) solvent dyes, disperse dyes, modified acidic and direct dyes, basic dyes, sulphide dyes, Vat Dye and the like.

One of the features of the present invention is that layered exfoliated nanoclay is used. In the present invention, the nano-clay can perform various roles. Firstly, the colored pigment reduces the part which interferes with the ultraviolet curing, and not only increases the adhesion, but also increases the responsiveness to the external behavior of the material due to the buffering property of the card structure formed by the layered exfoliated nano clay. In addition, the highly stable structure prevents the leakage of harmful substances to greatly reduce the irritation to the skin, and the dispersed nano-clay improves the storage stability by reducing the reaction between the oligomer and the monomer at the time of storage. Nano-clay also improves the compatibility with other materials, and thus has a characteristic of improving coatability.

The layered exfoliated nanoclay itself introduced in the present invention is also helpful in improving the functions such as antibacterial, antifungal, heat resistance, flame retardancy, and deodorization. The layer-separated nano-clay used in the present invention will be described first. The raw material of the clay used in the present invention is a clay having excellent water swelling properties such as natural bentonite, hectorite and the like, which is a layered clay of the smectite group, and more specifically montmorillonite belonging to this group. After pre-treatment and drying of acid and base, it is ground by using ball mill or the like. Many patents have been filed by Rohm and Haas Company for these patents. PCT / US2001 / 28989, PCT / US2001 / 28990, PCT / US2001 / 28991 and PCT / US2001 / 28994 show this. In this case, the interlayer spacing of the layered clay is not wide, but it is hydrated and purified by cation exchange, and the organic agent is added to make it hydrophilic and hydrophobic. Then, the organic agent is blown off to remove the layered delaminated nanoclay I make it. This structure is called a card house structure. In recent years, layered exfoliated nanoclases in a form of widening interlayer spacing have been provided through various methods. The nano-clay in the present invention refers to a layer-separated nano-clay.

In the present invention, the delaminated nano-clay may include 10 to 50 parts by weight of the delaminated nano-clay with respect to 100 parts by weight of the oligomer end-modified with an unsaturated group. And is suitable for expressing the above characteristics. In the present invention, it is more preferable to previously knead the colored pigment with the nano-clay. The process of kneading is to insert colored pigments in the interlayer structure of the nanoclay. In the case of nano-clay, the choice of pigment is expanded because it has both lipophilic and hydrophilic moieties. In the process of producing the ink, when the solution is in a state of solution after heating, the coloring pigment enters the card housing in a sufficient kneading process. Other components can also be stabilized with the nanoclay.

According to the present invention, the curability does not deteriorate in spite of the use of the colored pigment, whereby the adhesive force can be increased and the durability of the printing can be increased. In addition, physical properties such as minimization of skin irritation and storage stability are also improved.

Hereinafter, preferred embodiments and experimental examples are presented to explain the present invention in more detail. The following Examples and Experiments are only an embodiment of the present invention, and the present invention is not limited by the methods described below.

≪ Preparation of ultraviolet curable ink &

The terminally modified epoxy acrylate oligomer was Bbecryl 600 from SK Cytec, the terminally modified ester and the acrylate oligomer was Bbecryl 830 from SK Cytec. Trimethylolpropane acrylate was purchased from Orient ink and used as an acrylic monomer. The layered exfoliated nanoclay was purchased from Double UB Tech. IRGACURE 379, 819, and 127 (iba Specialty Chemicals; Basel, Switzerland) were used as photoinitiators, and gelling agents and other conventional additives were used. The mixture was heated and stirred until all the components were completely dissolved. Finally, the pigment was added and further stirred at 10,000 rpm for 30 minutes to knead.

Example 1

40 parts by weight of monorail, 40 parts by weight of nano clay, 100 parts by weight of pigment, 10 parts by weight of photoinitiator, small amount of gelling agent, small amount of dispersing agent and small amount of other additives were prepared per 100 parts by weight of epoxy acrylate oligomer.

Example 2

Was prepared in the same manner as in Example 1, except that a polyester acrylate oligomer was used.

Example 3

The epoxy acrylate oligomer and the polyester were prepared in the same manner as in Example 1 except that the acrylate oligomer was used in half.

Comparative Examples 1 to 3

In Examples 1 to 3, this was carried out except for the delaminated nanoclay.

<Hardness>

The composition prepared in the above Examples and Comparative Examples was applied to a glass plate having a size of 20 cm x 20 cm and the bar coater was fixed to a thickness of 1 to 2 mils and then pushed into a nitrogen fixation fixed mold (nitrogen flow rate: 40 lpm) 12-QN) at a speed of 30 fpm and a light intensity of 1.0 J / cm &lt; 2 &gt; using a 600 Watt 9 mm D-bulb. A sample of the cured composition film separated from the glass plate was measured for its degree of curing using Nicolet (model: protege 460, ATR mode).

The examples generally showed a curing degree of 95% or more, and the curing degree of Example 1 using epoxy acrylate was the best. Followed by Example 3 and Example 2 which were mixed and used in that order. However, ester acrylate has excellent reactivity and is considered in view of the variety of materials, and it was confirmed that the degree of curing is not so bad even when used in combination. The comparative examples remained at a degree of hardening of about 85%, which means that hardening was hindered by the use of colored pigments when nanoclay was not used.

<Surface leveling after curing>

The composition prepared in the above example was applied to a glass plate having a size of 20 cm x 20 cm and the bar coater was fixed to a thickness of 1 to 2 mil and then pushed into a nitrogen fixation fixed mold (nitrogen flow rate: 40 lpm) ) Of 600 Watt 9 mm D-bulb at a speed of 30 fpm and a light intensity of 1.0 J / cm 2 to produce a film having a thickness of about 20 μm. The surface of the prepared specimen was rubbed with the naked eye and fingers.

The examples generally showed that the surface of the specimen was uniformly smooth and the pigment particles were not exposed on the surface. In the comparative examples, the pigment particles were not exposed on the surface, but the surface of the specimen was not smooth.

<Surface Hardness>

ASTM D3369 method was used. If the pencil is applied to the plane of the printed specimen at an angle of 45 degrees and the specimen is pushed to a load of 1 kg and measured 5 times, the hardness value of the pencil is taken as the hardness value of the surface if the scratching or coating film is not broken more than 2 times.

In the case of the examples, the results were 6H or more, and the results of Examples 1 and 3 were superior to those of Example 2. In the comparative example, a crack occurred.

<Adhesion>

ASTM D3359 method was used. Draw 11 lines in each of the width and height with a knife to reach the material with the interval of 1mm on the cured hardened coating film, attach cellophane tape excellent in adhesion strength on 1mm 1mm 100 spaces and remove it abruptly close to 180 ° angle In this case, count the number of squares separated. 100/100 means complete adhesion to substrate and 0/100 means no adhesion.

Examples 1 and 3 showed complete adhesion, and Example 2 also showed 95 or more. The comparative examples showed an overall degree of 85. ]

<Color>

The color was measured by preparing a solid patch print on a DCEG paper with a resolution of 525x450 and a droplet size of 24 ng. Printed product was measured using a spectrophotometer Spectrolino, D50 light source, ^20.

Overall, the printing quality of the examples was excellent.

<Storage stability>

The viscosity of the ink compositions of the examples and the comparative examples when stored at 50 占 폚 for 5 days was compared with the initial viscosity value, and the rate of change with respect to the initial value was evaluated. In the case of the examples, the rate of change was all less than 5%, and in the case of the comparative example, the rate of change was more than 10%.

<Sintering>

It is considered that not only the stabilization of the pigment but also the surface elasticity or adhesion of the ink are enhanced, and the ink is stabilized and the storage stability is also increased. In addition, the overall curability and adhesiveness are considerably improved, which is considered to be preferable for use in printing inks for images.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. In the context of the present invention.

Claims (5)

In an ultraviolet curable ink composition comprising an oligomer end-modified with an unsaturated group, a photopolymerizable monomer, a photopolymerization initiator, a gelling agent and a coloring pigment,
Further comprising 10 to 50 parts by weight of the layered exfoliated nano-clay with respect to 100 parts by weight of the oligomer end-modified with the unsaturated group. The method according to claim 1,
Wherein the layered exfoliated nanoclay and the coloring pigment are added by kneading so that the coloring pigment is contained in the card collection structure of the layered exfoliated nano clay. 3. The method of claim 2,
Wherein the oligomer end-modified with the unsaturated group is a mixed acrylic oligomer comprising an ester acrylate and an epoxy acrylate. The method of claim 3,
Wherein the photopolymerizable monomer is an acrylic monomer. The method according to claim 1,
Wherein the gelling agent is a composite gelling agent comprising a curable polyamide and a curable epoxy acrylate.