JPH0491174A - Ultraviolet curing ink composition - Google Patents

Abstract

PURPOSE:To provide the subject composition composed mainly of a mixture of a styrene resin, a reactive diluent and an ultraviolet polymerization initiator at specific ratios, forming a coating film having high gloss after curing and exhibiting excellent adhesivity to various plastics and inorganic materials. CONSTITUTION:The objective composition is composed mainly of a mixture of 20-60wt.% of a styrene resin having a softening point of >=70 deg.C (e.g. PS and poly-alpha-methylstyrene resin), a reactive diluent having a molecular weight of <=1,000 (e.g. N-vinyl-2-pyrrolidone) and 1-10wt.% of an ultraviolet polymerization initiator (e.g. benzoin).

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is an ultraviolet curable ink composition that forms a high-gloss film after curing with ultraviolet rays and has excellent adhesion to not only various plastics but also inorganic materials. Regarding.

(Prior art) Some ultraviolet curable inks have traditionally had a high solids content, a luxurious finish, reduced energy required for drying, and quick curing at low temperatures, improving work efficiency. The product has attracted attention due to its numerous benefits, such as improving the quality of water, preventing air pollution, and improving the working environment. Used for printing.

In addition, most of these conventional UV-curable inks are
Only a low molecular weight photopolymerizable oligomer and a reactive diluent are used as the resin components of the ink.

(Problem to be Solved by the Invention) However, conventional ultraviolet curable inks do not contain volatile components and contain approximately 100% of the components that turn into resin through ultraviolet curing.
%, which ensures quick curing without going through an evaporation drying process, but the adhesion range of the ink to the material is not necessarily wide, so it is necessary to select and use different inks depending on the type of material. is the current situation.

In addition, most of these UV-curable inks use only low-molecular-weight photopolymerizable oligomers and reactive diluents as the resin components of the ink, so the shrinkage of the ink during curing causes the ink and the material to deteriorate. There have been problems in that peeling stress acts between the ink and the material, and even when the ink is in close contact with the material, the material is significantly deformed. In addition to these, it is currently desired to develop an improved ink that forms a film with high gloss.

Accordingly, an object of the present invention is to provide a novel ultraviolet curable ink composition that overcomes all of the drawbacks of conventional inks and has excellent properties that can be applied to a wide range of materials.

(Means for Solving the Problems) As a result of intensive research to solve the above problems, the present inventors have found that
It has been discovered that a surprising synergistic effect can be exerted by blending a styrene resin, a reactive diluent, and an ultraviolet polymerization initiator in a certain ratio and using this as the main component of an ink composition, and in order to achieve the present invention. It's arrived.

That is, the present invention mainly consists of a compound consisting of 20 to 60% by weight of a styrene resin with a softening point of 70° C. or higher, 10 to 40% by weight of a reactive diluent with a molecular weight of 1000 or less, and 1 to 10% by weight of an ultraviolet polymerization initiator. It is an ultraviolet curable ink containing a photopolymerizable oligomer, a pigment, an antifoaming agent, and a leveling agent as required.

The present invention will be explained below based on its configuration.

Examples of the styrene resin with a softening point of 70°C or higher used in the ultraviolet curable ink of the present invention include polystyrene resin, polyα-methylstyrene resin, vinyltoluene-α-methylstyrene copolymer resin, styrene-modified polyterpene resin, etc. There are ultraviolet polymerizable resins, non-polymerizable resins, etc., and one type or two or more types can be used in combination as necessary. Here, the softening point of styrene resin is 7.
The reason why the temperature must be 0°C or higher is because if the temperature is lower than 70°C, the strength of the film after UV curing will not be sufficient and the problem of blocking will occur, which is not preferable.

In addition, the blending ratio of the styrene resin is 20 to 6
0% by weight is preferred. If it is less than 20% by weight, the crosslinking density of the resulting ink composition will be extremely high and the adhesion will be reduced, while if it is more than 60% by weight, the crosslinking density of the ink composition will be extremely low. This is because a hardened film cannot be obtained.

Next, the reactive diluent with a molecular weight of 1000 or less used in the present invention may be either monofunctional or polyfunctional, such as N-vinyl-2-pyrrolidone, methyl (meth)acrylate, ethyl (meth)acrylate, etc. , butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N
~ Monofunctional polymerization monomer of ruacroylmorpholine, L4
-phthanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1.8-octanediol di(meth)acrylate, 1.9- Nonanediol di(meth)acrylate, bisphenol A-modified di(meth)acrylate, bis(acryloxyneopentyl glycol) adipate, dicyclopentenyl di(
meth)acrylate, hydroxypivalic acid neobentyl glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, trimethylolpropane ethylene oxide adduct tri(meth)acrylate, trimethylol propane tri(meth)acrylate,
There are polyfunctional (meth)acrylates 1 such as pentaerythritol tetra(meth)acrylate and dipentaerythritol hexa(meth)acrylate, and one or more of them may be used in combination as necessary. Here, the molecular weight of the reactive diluent is 1000 or less, but if the molecular weight is 1000 or more, the crosslinking density and curability of the obtained ink composition will deteriorate and a tough cured film will not be formed. The amount of reactive diluent used is preferably 10 to 40% by weight, and if it is less than 10% by weight,
The viscosity becomes too high to be practical as an ink. Furthermore, if the amount exceeds 40% by weight, the crosslinking density of the ink composition becomes extremely high, and deformation during curing progresses beyond the effect of the styrene resin to prevent curing shrinkage, causing problems in adhesion to materials. I don't like it.

Examples of the ultraviolet polymerization initiator include hengeine, benzoin alkyl ether, hensyl, benzyl dimethyl ketal, benzophenone, Michler's ketone, azoisobutyronitrile, 1-azobisl-cyclohexanecarbonitrile, naphthalenesulfonyl chloride, anthraquinone, hiimidazole, and thioxanthone. There is,
Use one type or a combination of two or more types as necessary. The blending ratio is preferably 1 to 10% by weight; if it is less than 1% by weight, the curability of the ink will be poor, and if it is more than 10% by weight, the cost of producing the ink will become too high, which is not preferred.

In addition, epoxy (meth), which is commonly used to promote photocurability in the production of ultraviolet curable inks,
2 to 2 polyfunctional fast-curing photopolymerizable oligomers such as acrylate oligomers, polyester (meth)acrylate oligomers, and urethane (meth)acrylate oligomers.
0% by weight, preferably 5 to 10% by weight, of sensitizing aids such as tertiary amines such as P-dimethylaminobenzoic acid ethyl ester and P-dimethylaminebenzoic acid isoamyl ester to 30 to 30% by weight of the photopolymerization initiator. 100% by weight, 2 organic pigments
~8% by weight or 10 to 50% by weight of inorganic pigment, 0.2 to 1% by weight of pigment dispersant, 1 to 10% by weight of waxes, and a flow control agent to provide printability and a constant coating state. Various additives such as an antifoaming agent and a leveling agent for maintaining the temperature can be added in an amount of 0.2 to 2.0% by weight, respectively, as desired.

By thoroughly kneading and dispersing a mixture of the above raw materials using a suitable method such as a roller mill, an ultraviolet curable ink having the composition of the present invention can be obtained.

In the ultraviolet curable ink of the present invention, the styrene resin contained in the ink has a high refractive index, so by using this, a remarkable high gloss can be obtained as an ink, and the resin also provides cushioning against curing shrinkage of the ink. Acts as an agent. Furthermore, by using the resin in combination with a polyfunctional polymer, a highly crosslinked polymer is produced, and an ink with good solvent resistance and protected styrenic resin can be obtained.

(Example) The present invention will be explained below with reference to the following Examples and Comparative Examples.

Here, all numerical values are expressed in % by weight.

Real 1 cone [L2i Styrene resin is added to N vinyl-2 in the blending ratio shown in Table 1.
- Dissolved in pyrrolidone at room temperature and under normal pressure, and after adding a pigment dispersant and making it uniform, the pigment was added.

Further, the remaining raw materials were mixed and stirred well under the same conditions as above, and then kneaded three times with a three-roll roll (if a pigment was blended, until the dispersed particle size was 5 μm or less). An ultraviolet curable ink was obtained.

Table 1*1. Manufactured by Rika Vercules Co., Ltd., product name, styrene resin *2. Manufactured by Rika Vercules Co., Ltd., product name, styrene resin *3. Manufactured by Exxon Chemical Co., Ltd., product name, aliphatic petroleum resin *4. Manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd., trade name, urethane acrylate oligomer *5. Manufactured by GAF Co., Ltd., trade name, N-vinyl 2-pyrrolidone*6. Manufactured by Rika Vercules Co., Ltd., product name, styrene resin *7. Manufactured by Mitsubishi Yuka Co., Ltd., trade name, bisphenol-modified acrylate monomer *8. Manufactured by San Nobuco Co., Ltd., trade name, polyfunctional acrylate monomer *9. Manufactured by Daicel NCB Ltd., trade name, polyfunctional acrylate oligomer *10. Manufactured by Shin-Nakamura Chemical Co., Ltd., trade name, trimethylolpropane triacrylate *11. Manufactured by Chiha Geigi Co., Ltd., trade name, photopolymerization initiator *120 Manufactured by Nippon Kayaku Co., Ltd., trade name, photopolymerization initiator *1
31 Manufactured by Nippon Kayaku Co., Ltd., trade name, sensitizing aid *14. Manufactured by German Additive Co., Ltd., trade name, antifoaming agent *15. Big Chemie Co., Ltd., trade name, pigment dispersant *16.8ASF Co., Ltd., trade name, R material
Printing was carried out on various adherends using a screen plate prepared under the condition that the emulsion thickness was 10 am.

After printing, high-pressure mercury lamp (manufactured by Oak Co., Ltd.), air-cooled type 80
The ink was cured under the conditions of a lamp height of 15 cm from the belt surface and a conveyor speed of 6 m/min, and a test piece was prepared.

This specimen was tested for cross-cut Sellotape peeling test (
The adhesion was measured according to JIS K-6400), the scratch resistance was measured by scratching with a fingernail, and the surface gloss was measured using a gloss meter (manufactured by Tokyo Denshoku Co., Ltd.). The results are shown in Table 2.

``Konoki''
The same procedure as in Example 1 was conducted using the blending ratios shown in the table. The test results are shown in Table 2.

(Effects of the Invention) As explained above, the ultraviolet curable ink of the present invention has little shrinkage when cured by ultraviolet rays, forms a high-gloss film after curing with ultraviolet rays, and can be applied to various materials such as various plastics as well as inorganic materials. It has excellent adhesion to the adherend, and even in the case of flexible adherends, it has good ability to follow bending and bending, does not cause cracks, does not easily scratch the surface, and is strong. It has the effect of being able to form an ink film.

Procedural amendment Heisei 2

Claims (1)

[Claims] 1. The main component is a mixture consisting of 20-60% by weight of a styrene resin with a softening point of 70°C or higher, 10-40% by weight of a reactive diluent with a molecular weight of 1000 or less, and 1-10% by weight of an ultraviolet polymerization initiator. An ultraviolet curable ink composition characterized by: