JP2009046605A - Ultraviolet-curable ink composition and printed matter using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultraviolet-curable ink composition which is reduced in the transpiration level or the like of volatile organic compounds (VOC) as a sickhouse snydrome source, without conducting an afterbaking treatment, and to provide a printed matter using the ink composition. <P>SOLUTION: Provided is an ultraviolet-curable ink composition comprising 0-15 wt.% of N-vinyl caprolactam as a curing component and a printed matter using the ink composition. The above ink composition also comprises, as other curing components, a mixture of two or more urethane acrylate oligomers including a polycarbonate skeleton-bearing urethane acrylate oligomer being 2,500-10,000 in weight-average molecular weight, a mixture of (meth)acrylate monomers including a phenoxyethyl acrylate monomer, and an acrylamide compound. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ultraviolet curable ink composition and a printed display. In particular, the present invention relates to an ultraviolet curable ink composition having a small amount of volatile organic compound (VOC) emitted from a sick house and a printed display using the same without performing after-baking.

Ultraviolet curable inks are substantially used because they are substantially free of solvents and are superior to solvent-based inks in terms of occupational safety, environmental pollution, fire prevention, etc. Yes.
As such an ultraviolet curable ink, there has been proposed a radiation curable resin composition that is excellent in curability, excellent in adhesion to various plastic substrates, and suitable for decorative plywood and the like (for example, see Patent Document 1).
More specifically, urethane (meth) acrylate which is a reaction product of polycarbonate diol, diisocyanate compound and hydroxyalkyl (meth) acrylate, and a reaction product of polyol having a predetermined hydroxyl group, diisocyanate compound and hydroxyalkyl (meth) acrylate A urethane (meth) acrylate that is a reaction product of urethane (meth) acrylate, a carboxyl-containing (meth) acrylate, and a photopolymerization initiator, and if desired, It is a photocurable resin composition further containing N-vinylcaprolactam and the like.

Further, there has been proposed a photocurable resin composition that is cured by irradiation with light for a short time and gives a cured product that is excellent in flexibility and appearance and has no surface tack (see, for example, Patent Document 2).
More specifically, one or two types of a polycarbonate diol-modified urethane prepolymer having a (meth) acryloyl group, which is a reaction product of a hydroxyl group-containing (meth) acrylate, polyisocyanate and polycarbonate diol, and (meth) acrylate, A photocurable resin composition comprising a photopolymerization initiator, and a photocurable resin composition further containing N-vinylcaprolactam or the like, if desired.

In addition, a photocurable resin composition containing a polycarbonate diol-modified urethane prepolymer has been proposed as an optical fiber coating material having a predetermined elastic modulus in a wide temperature range (−40 ° C. to 60 ° C.) (for example, patents). Reference 3).
More specifically, polycarbonate diol-modified urethane prepolymer having an ethylenically unsaturated group, which is a reaction product of polycarbonate diol, (meth) acrylate having a hydroxyl group, and polyisocyanate, and N-vinylcaprolactam as a reactive diluent And a photopolymerization initiator.

On the other hand, development of ultraviolet curable ink corresponding to volatile organic compounds (hereinafter referred to as VOC) is desired by the industry.
In other words, the Ministry of Health, Labor and Welfare has instructed to measure the indoor concentration of VOC regulated substances (formaldehyde, acetaldehyde, toluene, xylene, ethylbenzene, styrene) as a countermeasure against sick house. It is necessary to provide a reference value for the VOC amount (dispersion amount) and take measures to reduce it.

Then, the photocurable resin composition excellent in the adhesive sheet characteristic is proposed while adapting to this VOC countermeasure (for example, refer patent document 4).
More specifically, it is a resin composition for a pressure-sensitive adhesive sheet substrate containing urethane acrylate and a reactive diluent, and optionally a resin composition for a pressure-sensitive adhesive sheet substrate further containing N-vinylcaprolactam or the like.
JP-A-8-92342 JP-A-6-145276 Special table 2006-502425 gazette JP 11-189762 A

However, the photocurable resin compositions described in Patent Documents 1 to 3 contain N-vinylcaprolactam for improving the adhesion to the base material, etc., although it is an optional component, and it is hydrolyzed. Thus, there was a problem that acetaldehyde as VOC was easily dissipated.
In addition, with respect to Patent Document 4, although it is certainly possible to suppress the emission of VOCs in the manufacturing process etc. as compared with conventional thermoplastic resins such as polyethylene, engineering plastics such as polyethylene terephthalate, etc. However, no consideration is given to the suppression of VOCs that are diffused over time, and it is difficult to say that the VOC regulations are met.
Therefore, an attempt has been made to reduce the VOC amount by subjecting the coating film formed by ultraviolet irradiation to, for example, after baking at 80 to 100 ° C. for 1 hour or more.
However, there are further problems such as variations in after-baking treatment, resulting in insufficient reduction in the amount of VOC, thermal damage to the base material, or the need for special after-baking equipment. It was.

Accordingly, as a result of intensive studies on the conventional problems, the present inventors have limited the amount of N-vinylcaprolactam added to a predetermined range and two or more types of urethane acrylate oligomers including a polycarbonate skeleton urethane acrylate oligomer having a specific average molecular weight. And a mixture of a (meth) acrylate monomer containing a phenoxyethyl acrylate monomer, and an acrylamide compound, there is a conflict between the adhesion to the substrate and the adjustment of the VOC amount without performing after-baking treatment. The inventors have found that easy characteristics can be satisfied, and have completed the present invention.
In addition, the present inventors have found that by using a specific photopolymerization initiator, it is possible to satisfy the balance between the adhesiveness to the substrate and the easily conflicting properties of adjusting the VOC amount in a balanced manner.
That is, the present invention provides an ultraviolet curable ink composition that does not undergo after-baking treatment, has a low VOC emission amount for a sick house, and has excellent adhesion to a substrate, and a printed display using the same. The purpose is to provide.

According to the present invention, there is provided an ultraviolet curable ink composition in which the amount of N-vinylcaprolactam added as a curing component is 0% by weight or 15% by weight or less (excluding 0% by weight) based on the total amount. A mixture of two or more urethane acrylate oligomers including a polycarbonate skeleton urethane acrylate oligomer having a weight average molecular weight of 2,500 to 10,000 as a curing component, and a mixture of (meth) acrylate monomers including a phenoxyethyl acrylate monomer An ultraviolet curable ink composition containing an acrylamide compound is provided, and the above-described problems can be solved.
That is, by limiting the addition amount of N-vinylcaprolactam to a predetermined range, by using a mixture of urethane acrylate oligomers including a predetermined oligomer, a mixture of (meth) acrylate monomers including a predetermined monomer, and an acrylamide compound, Without performing after-baking treatment, it is possible to satisfy the conflicting characteristics of adhesion to the substrate and adjustment of the VOC amount.

Further, in constituting the ultraviolet curable ink composition of the present invention, as a urethane acrylate oligomer other than the polycarbonate skeleton urethane acrylate oligomer, a polyester skeleton urethane acrylate oligomer having a weight average molecular weight of 2,000 to 15,000 and a weight average molecular weight. It is preferable to include a polycaprolactone skeleton urethane acrylate oligomer having a 2,000 to 15,000 or any one of them.
By comprising in this way, a cure rate can be improved, maintaining the adhesiveness with a base material effectively.

Moreover, when comprising the ultraviolet curable ink composition of this invention, it is preferable to make the addition amount of a polycarbonate frame | skeleton urethane acrylate oligomer into the value within the range of 5 to 50 weight% with respect to the whole quantity.
By comprising in this way, the adhesiveness with respect to a base material can be improved, maintaining a cure rate effectively.

Moreover, when comprising the ultraviolet curable ink composition of this invention, it is preferable to make the addition amount of an acrylamide compound into the value within the range of 1-35 weight% with respect to the whole quantity.
By comprising in this way, the adhesiveness with respect to a base material can further be improved.

In constituting the ultraviolet curable ink composition of the present invention, it is preferable that dicyclopentanyl acrylate is further included as a (meth) acrylate monomer.
By comprising in this way, adhesiveness and a cure rate can be improved further.

Moreover, when comprising the ultraviolet curable ink composition of this invention, it is preferable to make the addition amount of a (meth) acrylate monomer into the value within the range of 1-35 weight% with respect to the whole quantity.
By comprising in this way, the adhesiveness with a base material can be improved, and the predetermined | prescribed hardness as a cured coating film can be obtained easily, maintaining a cure rate effectively.

Further, in constituting the ultraviolet curable ink composition of the present invention, it contains two or more kinds of photopolymerization initiators as the photopolymerization initiator of the ultraviolet curable ink composition, and the content of the photopolymerization initiator. Is preferably set to a value in the range of 0.1 to 20% by weight based on the total amount.
By comprising in this way, the mixture of the oligomer component and monomer component mentioned above can be made to react more efficiently, and a curing rate can be accelerated easily.

Further, in constituting the ultraviolet curable ink composition of the present invention, as a photopolymerization initiator, a combination of an acyl phosphine oxide compound and an α-hydroxyketone compound, or an acyl phosphine oxide compound and a keto It is preferable to use a combination with a sulfone compound.
By comprising in this way, a cure rate is accelerated | stimulated and the dissipation of VOC can be reduced further more effectively.

  Another aspect of the present invention is a printed display product comprising a printed layer obtained from any of the ultraviolet curable ink compositions described above.

[First Embodiment]
1st Embodiment of this invention is an ultraviolet curable ink composition whose addition amount of N-vinyl caprolactam is 0 weight% or 15 weight% or less with respect to the whole quantity as a hardening component, Comprising: As a mixture of two or more urethane acrylate oligomers including a polycarbonate skeleton urethane acrylate oligomer having a weight average molecular weight of 2,500 to 10,000, a mixture of (meth) acrylate monomers including a phenoxyethyl acrylate monomer, and an acrylamide compound And an ultraviolet curable ink composition.
Hereinafter, each component of the first embodiment will be described in detail.

1. Mixture of urethane acrylate oligomer (1) Polycarbonate skeleton urethane acrylate oligomer The urethane acrylate oligomer used in the first embodiment uses a mixture of at least two urethane acrylate oligomers having different skeletons, one of which is It is a polycarbonate skeleton urethane acrylate oligomer.
The reason for this is that even when the amount of N-vinylcaprolactam added is less than or equal to a predetermined amount by using a mixture of urethane acrylate oligomers including such a polycarbonate skeleton urethane acrylate oligomer, This is because a predetermined hardness as a cured coating film can be obtained.
Even when a mixture of a plurality of polycarbonate skeleton urethane acrylate oligomers having different weight average molecular weights or structural unit structures is used as the mixture of urethane acrylate oligomers, a predetermined effect can be obtained.

Here, the polycarbonate skeleton urethane acrylate oligomer is a reaction product of a polycarbonate skeleton polyol, an organic polyisocyanate compound and a hydroxy acrylate.
The weight average molecular weight of the polycarbonate skeleton urethane acrylate oligomer is set to a value in the range of 2,500 to 10,000.
The reason for this is that when the weight average molecular weight of the polycarbonate skeleton urethane acrylate oligomer is less than 2,500, the curing rate is excessively increased, and the adhesion with the base material is likely to occur, which makes handling difficult. Because there is. On the other hand, when the weight average molecular weight of the polycarbonate skeleton urethane acrylate oligomer exceeds 10,000, the curing rate is excessively decreased, and it may be difficult to effectively suppress the emission of VOC.
Therefore, the weight average molecular weight of the polycarbonate skeleton urethane acrylate oligomer is preferably set to a value within the range of 3,000 to 8,000, and more preferably set to a value within the range of 3,500 to 6,000.

  In addition, the type of polycarbonate skeleton polyol for obtaining the polycarbonate skeleton urethane acrylate is not particularly limited, but is a polycarbonate skeleton diol compound because it is easily available industrially and is relatively inexpensive. Is preferred.

  Moreover, as a kind of organic polyisocyanate compound for obtaining a polycarbonate frame | skeleton urethane acrylate, non-yellowing types, such as isophorone diisocyanate, hexamethylene diisocyanate, 4,4-dicyclohexylmethane diisocyanate, and trimethylhexamethylene diisocyanate, are preferable.

  Moreover, as hydroxy acrylate for obtaining polycarbonate frame | skeleton urethane acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, caprolactone modified | denatured 2-hydroxyethyl acrylate, etc. are preferable.

Moreover, it is preferable to make the addition amount of a polycarbonate frame | skeleton urethane acrylate oligomer into the value within the range of 5 to 50 weight% with respect to the whole quantity.
This is because the adhesion to the substrate can be improved while the curing rate is more effectively maintained.
That is, when the addition amount of the polycarbonate skeleton urethane acrylate oligomer is less than 5% by weight, the curing rate is excessively lowered, and it may be difficult to effectively suppress the emission of VOC. On the other hand, when the addition amount of the urethane polycarbonate skeleton urethane acrylate oligomer exceeds 50% by weight, the curing rate is excessively increased, and the adhesion with the base material is liable to occur, which may make handling difficult. Because.
Therefore, the addition amount of the polycarbonate skeleton urethane acrylate oligomer is more preferably set to a value within the range of 8 to 45% by weight, and further to a value within the range of 10 to 40% by weight, based on the total amount. preferable.

Next, the relationship between the addition amount of the polycarbonate skeleton urethane acrylate oligomer, the diffusion amount of acetaldehyde, and the adhesion will be described with reference to FIG.
That is, in FIG. 1, the horizontal axis represents the addition amount (% by weight) of the polycarbonate skeleton urethane acrylate oligomer relative to the total amount of the ultraviolet curable ink composition, and the left vertical axis represents the amount of acetaldehyde emitted (μg / 100 cm ^2). ) And a characteristic curve B taking adhesion (relative evaluation) are shown on the right vertical axis.
At this time, the addition amount of N-vinylcaprolactam with respect to the total amount of the ultraviolet curable ink composition is 0 to 15% by weight, the addition amount of the urethane acrylate oligomer containing the polycarbonate skeleton urethane acrylate oligomer is 13 to 30% by weight, phenoxy The addition amount of the mixture of (meth) acrylate monomers including the acrylate monomer was 10 to 25% by weight, and the addition amount of acrylamide was 1 to 10% by weight.
In addition, about the measurement conditions of the acetaldehyde emission amount, it describes in a subsequent Example. The relative evaluation of adhesion refers to the results of the cross-cut cello tape (registered trademark) peel test according to JIS K-5600 5.6, and the adhesion of the ultraviolet curable ink composition according to the following criteria. It has been evaluated.
4: The number of grids not peeled is 99% or more 3: The number of grids not stripped is less than 95 to less than 99% 2: The number of grids not stripped is less than 75 to 95% 1: The number of grids not stripped is 75 %Less than

That is, as understood from the characteristic curve A, the amount of acetaldehyde emitted decreases as the amount of the polycarbonate skeleton urethane acrylate oligomer increases.
More specifically, as the addition amount of the polycarbonate skeleton urethane acrylate oligomer increases from 0% by weight to 5% by weight, the amount of acetaldehyde emitted from the value of at least 35 μg / 100 cm ² or more is around 5 μg / 100 cm ^2. It can be seen that the value rapidly decreases to the value of. The added weight of the polycarbonate backbone urethane acrylate oligomer, in the range of more than 5 wt%, the generation amount of acetaldehyde, stable 5 [mu] g / 100 cm ² it can be seen that suppressed to a low value of about.

Moreover, as understood from the characteristic curve B, as the amount of addition of the polycarbonate skeleton urethane acrylate oligomer increases, the adhesiveness once improves and then decreases.
More specifically, as the addition amount of the polycarbonate skeleton urethane acrylate oligomer increases from 0% by weight to 5% by weight, it can be seen that the relative evaluation of adhesion is rapidly improved from 1 to 4. . In the range of 5 to 50% by weight of the polycarbonate skeleton urethane acrylate oligomer, the relative evaluation of adhesion can be maintained at a level of about 3 or more, and the addition amount of the polycarbonate skeleton urethane acrylate oligomer is increased. It can be seen that the relative evaluation of the adhesiveness gradually decreases and it becomes difficult to obtain sufficient adhesiveness.

  Therefore, from the characteristic curves A and B, by setting the addition amount of the polycarbonate skeleton urethane acrylate oligomer to a value within the range of 5 to 50% by weight with respect to the total amount, the emission of acetaldehyde as VOC is effectively suppressed. However, it turns out that the adhesiveness with respect to a base material can be hold | maintained effectively.

(2) Other urethane acrylate oligomers Other examples of the urethane acrylate oligomer other than the polycarbonate skeleton urethane acrylate oligomer include a polyester skeleton urethane acrylate oligomer, a polycaprolactone skeleton urethane acrylate oligomer, and a polyether skeleton urethane acrylate oligomer.
In particular, the other urethane acrylate oligomers preferably include a polyester skeleton urethane acrylate oligomer and / or a polycaprolactone skeleton urethane acrylate oligomer.
This is because the curing rate can be improved while effectively maintaining the adhesion to the substrate.

Moreover, it is preferable to make the weight average molecular weight of another urethane acrylate oligomer into the value within the range of 2,000-15,000.
The reason for this is that when the weight average molecular weight of the other urethane acrylate oligomer is less than 2,000, the curing rate is excessively increased, and the adhesion with the base material is liable to be caused and the handling becomes difficult. Because there is. On the other hand, when the weight average molecular weight of the other urethane acrylate oligomer exceeds 15,000, the curing rate is excessively lowered, and it may be difficult to effectively suppress the emission of VOC.
Therefore, the weight average molecular weight of the other urethane acrylate oligomer is more preferably set to a value in the range of 2,500 to 8,000, and more preferably set to a value in the range of 3,500 to 6,000.

Moreover, it is preferable to make the compounding ratio of another urethane acrylate oligomer into the value within the range of 70-300 weight part with respect to 100 weight part of polycarbonate frame | skeleton urethane acrylate oligomers, and the value within the range of 100-200 weight part, More preferably.
The reason for this is that if the blending ratio of the other urethane acrylate oligomers is too low, the curing rate may be excessively lowered and the VOC amount may be increased. On the other hand, when the blending ratio of the other urethane acrylate oligomer is excessively high, the curing rate is excessively increased, and poor adhesion to the base material is likely to occur or handling becomes difficult.

2. Mixture of (meth) acrylate monomers A mixture of (meth) acrylate monomers including a phenoxyethyl acrylate monomer is used to adjust the viscosity of the ultraviolet curable ink composition and the properties of the cured product.
That is, as a reactive diluent, for example, a compound having a (meth) acrylate monomer, a carboxyl group or an acid anhydride group obtained by an amidation or esterification reaction between a compound containing an amino group or a hydroxyl group and acrylic acid And a (meth) acrylate monomer obtained by an esterification reaction with an acrylate having a hydroxyl group.

More specifically, as the (meth) acrylate monomer, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, isobutyl acrylate, benzyl acrylate, ethyl carbitol acrylate, 2-ethylhexyl acrylate, methoxyethyl acrylate, methoxypolyethylene glycol acrylate, butoxyethyl acrylate , Butoxypolyethylene glycol acrylate, phenoxyethyl acrylate, nonylphenoxyethyl acrylate, phenoxypolyethylene glycol acrylate, 3-chloro-2-hydroxypropyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxybutyl acrylate, diethylene glycol monoacrylate, Dipropire Glycol monoacrylate, polyethylene glycol monoacrylate, polypropylene glycol monoacrylate, trifluoroethyl acrylate, dicyclopentadiene acrylate, isobornyl acrylate, dicyclopentenyloxyalkyl acrylate, dicyclopentanyl acrylate, tricyclodecanyl acrylate, tricyclo One kind alone or a combination of two or more kinds such as decanyloxyethyl acrylate may be mentioned.
Among them, it is preferable to use phenoxyethyl acrylate, isobornyl acrylate, and dicyclopentanyl acrylate as the (meth) acrylate monomer because of good adhesion and appropriate curing speed.
In particular, a dicyclopentanyl acrylate monomer is a particularly preferred (meth) acrylate monomer because it can further improve the adhesion and the curing rate.

Moreover, it is preferable to make the addition amount of a (meth) acrylate monomer into the value within the range of 1-35 weight% with respect to the whole quantity.
This is because not only can the adhesiveness with the base material be improved while effectively maintaining the curing rate, but also a predetermined hardness can be easily obtained as a cured coating film. The addition amount of (meth) acrylate monomer means the addition amount of a mixture of phenoxyethyl acrylate and other (meth) acrylate monomers.
In other words, if the amount of (meth) acrylate monomer added is less than 1% by weight, the curing rate increases excessively, and it tends to cause poor adhesion with the substrate, making handling difficult. is there. On the other hand, when the amount of the (meth) acrylate monomer added exceeds 35% by weight, the curing rate is excessively decreased, and it may be difficult to effectively suppress the emission of VOC.
Therefore, the addition amount of the (meth) acrylate monomer is more preferably set to a value within the range of 3 to 30% by weight with respect to the total amount, and further preferably set to a value within the range of 5 to 20% by weight. .

Next, the relationship between the amount of (meth) acrylate monomer added, the amount of acetaldehyde diffused, and the adhesion will be described with reference to FIG.
That is, in FIG. 2, the horizontal axis represents the addition amount (% by weight) of the (meth) acrylate monomer with respect to the total amount of the ultraviolet curable ink composition, and the left vertical axis represents the amount of acetaldehyde emitted (μg / 100 cm ^2). ) And a characteristic curve B taking adhesion (relative evaluation) are shown on the right vertical axis.
At this time, the addition amount of N-vinylcaprolactam is 0 to 15% by weight, the addition amount of the urethane acrylate oligomer including the polycarbonate skeleton urethane acrylate oligomer is 13 to 30% by weight, and the total amount of the ultraviolet curable ink composition, and The amount of acrylamide added was 1 to 10% by weight.
The conditions for measuring the amount of acetaldehyde diffused and the relative evaluation of adhesion are the same as in FIG.

That is, as understood from the characteristic curve A, the amount of acetaldehyde emitted increases as the amount of (meth) acrylate monomer added increases.
More specifically, it can be seen that when the amount of the (meth) acrylate monomer added is in the range of 0 to 35% by weight, the amount of acetaldehyde emitted stably holds a low value of about 5 μg / 100 cm ² . On the other hand, it can be seen that when the amount of (meth) acrylate monomer added exceeds 35% by weight, the amount of acetaldehyde emitted increases rapidly.

Moreover, as understood from the characteristic curve B, the adhesion improves as the amount of the (meth) acrylate monomer added increases.
More specifically, it can be seen that the relative evaluation of adhesion is rapidly improved from 1 to 4 as the addition amount of (meth) acrylate monomer is increased from 0 wt% to 5 wt%. . And if the addition amount of a (meth) acrylate monomer is the range of 1 weight% or more, it turns out that adhesive evaluation can be hold | maintained at the level of 3 or more.

  Therefore, from the characteristic curves A and B, the amount of (meth) acrylate monomer added is set to a value within the range of 1 to 35% by weight with respect to the total amount, thereby effectively suppressing the emission of acetaldehyde as VOC. However, it turns out that the adhesiveness with respect to a base material can be hold | maintained effectively.

3. Acrylamide Compound The ultraviolet curable ink composition of the present invention is characterized by containing at least one acrylamide compound.
This is because the adhesiveness with the substrate can be further improved by including a predetermined amount of the acrylamide compound.

  Here, as the acrylamide compound, diacetone acrylamide, isobutoxymethyl acrylamide, N, N-dimethylacrylamide, t-octylacrylamide, N, N-diethylacrylamide, N, N-butoxymethylacrylamide, N, N-dimethyl One kind alone or a combination of two or more kinds such as aminopropylacrylamide can be mentioned.

Moreover, it is preferable to make the addition amount of an acrylamide compound into the value within the range of 1-35 weight% with respect to the whole quantity.
The reason for this is that if the amount of the acrylamide compound added is excessively small, the curing rate increases, and adhesion failure with respect to the substrate tends to occur or handling becomes difficult. On the other hand, when the addition amount of the acrylamide compound is excessively large, the curing rate is excessively decreased and the VOC amount may be increased.
Therefore, the addition amount of the acrylamide compound is more preferably set to a value within the range of 3 to 30% by weight, and further preferably set to a value within the range of 5 to 20% by weight with respect to the total amount.

Next, the relationship between the amount of acrylamide compound added, the amount of acetaldehyde emitted, and the adhesion will be described with reference to FIG.
That is, in FIG. 3, the horizontal axis represents the amount of acrylamide compound added (% by weight) relative to the total amount of the ultraviolet curable ink composition, and the left vertical axis represents the amount of acetaldehyde emitted (μg / 100 cm ² ). The characteristic curve A and the characteristic curve B taking the adhesiveness (relative evaluation) are shown on the right vertical axis.
At this time, the addition amount of N-vinylcaprolactam is 0 to 15% by weight, the addition amount of the urethane acrylate oligomer including the polycarbonate skeleton urethane acrylate oligomer is 13 to 30% by weight, and the total amount of the ultraviolet curable ink composition, and The addition amount of the mixture of (meth) acrylate monomers was 10 to 25% by weight.
The conditions for measuring the amount of acetaldehyde diffused and the relative evaluation of adhesion are the same as in FIG.

That is, as understood from the characteristic curve A, as the amount of acrylamide compound added increases, the amount of acetaldehyde emitted increases.
More specifically, it can be seen that when the amount of the acrylamide compound added is in the range of 0 to 35% by weight, the amount of acetaldehyde released stably holds a low value of around 5 μg / 100 cm ² . On the other hand, it can be seen that when the amount of the acrylamide compound added exceeds 35% by weight, the amount of acetaldehyde emitted increases rapidly.

Moreover, as understood from the characteristic curve B, as the amount of the acrylamide compound added increases, the adhesion improves.
More specifically, it can be seen that the relative evaluation of adhesion is rapidly improved to 1 to 4 as the amount of acrylamide compound added increases from 0 wt% to 5 wt%. And if the addition amount of an acrylamide compound is the range of 1 weight% or more, it turns out that evaluation of adhesiveness can be hold | maintained at the level of about 3 or more.

  Therefore, from the characteristic curves A and B, by setting the addition amount of the acrylamide compound to a value within the range of 1 to 35% by weight with respect to the total amount, while effectively suppressing the emission of acetaldehyde as VOC. It can be seen that the adhesion to the substrate can be effectively maintained.

4). N-Vinylcaprolactam The ultraviolet curable ink composition of the present invention is characterized in that N-vinylcaprolactam has a value of 0% by weight or 15% by weight or less based on the total amount.
This is because VOC emission can be effectively suppressed by limiting the amount of N-vinylcaprolactam added to a predetermined range.
On the other hand, the adhesiveness etc. with respect to the base material of a photocurable resin composition may fall by restrict | limiting the addition amount of N-vinyl caprolactam.
In this regard, according to the present invention, since the predetermined urethane acrylate oligomer, (meth) acrylate monomer, and acrylamide compound described above are used, the amount of N-vinylcaprolactam is limited despite the fact that the amount of N-vinylcaprolactam is limited. The adhesiveness etc. with respect to the base material of a curable ink composition can be maintained effectively.
Therefore, since the balance between the adjustment of the VOC amount and the adhesion to the base material is in a more suitable range, the addition amount of N-vinylcaprolactam is set to a value within the range of 1 to 10% by weight. More preferably, the value is more preferably in the range of 2 to 5% by weight.

Next, the relationship between the amount of N-vinylcaprolactam added, the amount of acetaldehyde released and the adhesiveness will be described with reference to FIG.
That is, in FIG. 4, the horizontal axis represents the addition amount (% by weight) of N-vinylcaprolactam with respect to the total amount of the ultraviolet curable ink composition, and the left vertical axis represents the amount of acetaldehyde emitted (μg / 100 cm ² ). The characteristic curve A taking the adhesiveness and the characteristic curve B taking the adhesiveness (relative evaluation) are shown on the right vertical axis.
At this time, the addition amount of the urethane acrylate oligomer mixture including the polycarbonate skeleton urethane acrylate oligomer with respect to the total amount of the ultraviolet curable ink composition is 13 to 30% by weight, and the addition amount of the (meth) acrylate monomer mixture is 10 to 25%. %, And the amount of acrylamide added was 1 to 10% by weight.
The conditions for measuring the amount of acetaldehyde diffused and the relative evaluation of adhesion are the same as in FIG.

That is, as understood from the characteristic curve A, as the amount of N-vinylcaprolactam added increases, the amount of acetaldehyde emitted increases.
More specifically, it can be seen that when the amount of N-vinylcaprolactam added is in the range of 0 to 15% by weight, the amount of acetaldehyde diffused stably holds a low value of around 5 μg / 100 cm ² . On the other hand, it can be seen that when the amount of N-vinylcaprolactam added exceeds 15% by weight, the amount of acetaldehyde emitted increases rapidly.

Further, as understood from the characteristic curve B, the adhesion is improved as the amount of N-vinylcaprolactam added increases.
More specifically, when the addition amount of N-vinylcaprolactam is 0% by weight, the relative evaluation of adhesion has already taken a relatively high value of around 3, and the addition amount of N-vinylcaprolactam is It can be seen that the relative evaluation of the adhesion is improved from the value of about 3 to the value of about 4 with increasing from 0% by weight to 1% by weight. And even if the addition amount of N-vinylcaprolactam is the range of 1 weight% or more, it turns out that evaluation of adhesiveness can be hold | maintained to the level of 3 or more.

  Therefore, from the characteristic curves A and B, the amount of N-vinylcaprolactam added is set to a value within the range of 0% by weight or 15% by weight or less with respect to the total amount, thereby effectively releasing acetaldehyde as VOC. It can be seen that the adhesiveness to the substrate can be effectively maintained while suppressing.

5). Photopolymerization initiator The photopolymerization initiator used in the present invention is not particularly limited as long as it generates radicals by ultraviolet rays, and the radicals cause a polymerization reaction of a mixture of urethane acrylate oligomers, a mixture of (meth) acrylate monomers, or the like.
Specific examples of such a photopolymerization initiator include benzyl dimethyl ketal compounds such as 2,2-dimethoxy-1,2-diphenylethane-1-one; oligo [2-hydroxy-2-methyl-1- [ Α-hydroxy ketone compounds such as 4- (1-methylvinyl) phenyl] propanone] and 1-hydroxycyclohexyl phenyl ketone; 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropane-1 -One, α-aminoketone compounds such as 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1; diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, etc. Acylphosphine oxide compounds of 1- [4- (4-benzoylphenylsulfanyl) phenyl] -2-methyl Ketosulfone compounds such as -2- (4-methylphenylsulfonyl) propan-1-one; bis (η5-2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- (1H) Metallocene compounds such as -pyrrol-1-yl) -phenyl) titanium; 2,4-diethylthioxanthone, isopropylthioxanthone, 1-chloro-4-propoxythioxanthone, 2- (3-dimethylamino-2-hydroxypropoxy) 3 And thioxanthone compounds such as 4-dimethyl-9H-thioxanthone-9-one-mesochloride.

  Among the photopolymerization initiators described above, α-hydroxyketone compounds, acylphosphine oxide compounds, and ketosulfone compounds having a phenyl group generate radicals by ultraviolet rays, which radicals are photopolymerized oligomers and photopolymerization. The curing reaction is accelerated by reacting efficiently with the monomer mixture.

Moreover, the thing which extracts hydrogen, such as a thioxanthone type compound, produces | generates a radical, A hardening reaction is accelerated | stimulated by combining with a hydrogen donor.
Examples of the hydrogen donor include mercapto compounds and amine compounds. Among them, amine compounds are preferable. Examples of the amine compound include triethylamine, methyldiethanolamine, triethanolamine, diethylaminoethyl acrylate, p-dimethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, N, N-dimethylbenzylamine, 4,4′-bis (diethylamino) benzophenone, p-dimethylaminobenzoic acid ethyl ester, pentyl 4-dimethylaminobenzoate and the like.

Moreover, it is preferable to mix and use at least two kinds of photopolymerization initiators.
In particular, the curing rate and weather resistance are appropriate, and the amount of VOC can be effectively reduced. Therefore, an α-hydroxyketone compound or a ketosulfone compound is mixed with an acylphosphine oxide compound. It is preferable to use it.
In the case of constituting a colorless ultraviolet curable ink composition that does not contain a pigment or the like and does not use a colored pigment, in order to avoid the influence of coloring of the ultraviolet curable coating film, α- It is preferable to use only hydroxyketone compounds.

Further, the addition amount of the photopolymerization initiator is usually preferably a value within the range of 0.1 to 20% by weight, and a value within the range of 0.5 to 15% by weight relative to the total amount It is more preferable to set the value within a range of 3 to 10% by weight.
The reason for this is that if the amount of the photopolymerization initiator added is too small, the curing rate is remarkably lowered and the VOC emission may increase. On the other hand, when the addition amount of the photopolymerization initiator is too large, the curing rate increases, and it becomes easy to cause poor adhesion to the substrate, or the handling becomes difficult.

6). Pigment In addition, when constituting an ultraviolet curable printing ink, an inorganic coloring pigment, an organic coloring pigment, an organic extender pigment, an inorganic matting powder pigment, an organic matting powder pigment, or the like is added as a pigment. Is preferred.
That is, as preferred pigments, condensed azo pigments, diketopyrrolopyrrole pigments, perylene pigments, cuacridone pigments, isoindolinone pigments, dioxazine pigments, phthalocyanine pigments, etc., titanium pigments, zinc sulfide pigments And inorganic pigments such as carbon black pigments and iron oxide pigments.
Examples of extender pigments include silica, talc, clay, calcium carbonate, magnesium carbonate, barium sulfate, and various resin beads.
In addition, a pigment is comprised by 1 type, or 2 or more types of mixing | blending according to the use purpose of ink, for example, the objectives, such as a matte color.
The addition amount of the pigment is determined in a range that does not inhibit the ultraviolet curing rate and does not lower the object of the present invention, and is usually used in a range of 1 to 50% by weight with respect to the total amount.

7). Additives In addition, antifoaming agents, leveling agents, pigment wetting agents, dispersants, flow regulators, thermal polymerization inhibitors, oxidation polymerization inhibitors for the purpose of adjusting ink and printability in UV-curable printing inks. Etc. can be used.

[Second Embodiment]
The second embodiment of the present invention is an ultraviolet curable ink composition in which the addition amount of N-vinylcaprolactam is 0% by weight or 15% by weight or less as a curing component, As obtained from an ultraviolet curable ink composition containing a mixture of two or more urethane acrylate oligomers including a polycarbonate skeleton urethane acrylate oligomer, a mixture of (meth) acrylate monomers including a phenoxyethyl acrylate monomer, and an acrylamide compound. A printed display product comprising a printed layer.
Hereinafter, the second embodiment of the present invention will be described in detail.

1. Printing layer The printing layer made of UV-curable printing ink is a layer consisting of a combination of characters, figures, symbols, etc. obtained by printing, and includes decorative layers, decorative layers, protective layers, foundation layers, etc. .
Moreover, although the thickness of this printing layer is based also on a use, it is usually in the range of 1 μm to 1 mm, more preferably in the range of 10 μm to 50 μm, and preferably in the range of 5 μm to 50 μm. Further preferred.
Further, such a print layer is preferably composed of a plurality of layers, such as a combination of an underlayer, an intermediate layer, and a protective layer, depending on applications and functions.

2. Substrate The substrate to which the ultraviolet curable printing ink is applied is usually a plastic substrate, and in particular, a polycarbonate plate, a polycarbonate film, a PET film, an acrylic plate, a painted metal, and the like can be mentioned. Moreover, as such a base material, a glass or metal base material may be sufficient.

3. Production method The production method of the printed display is not particularly limited, but for example, after applying it to a substrate such as a polycarbonate plate by a coating method such as roll coating, gravure coating, dip coating, or flow coating. It can be produced by irradiation with a predetermined amount of ultraviolet rays.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples.

[Example 1]
1. Preparation of UV curable ink composition Into the container, urethane acrylate oligomers and the like were added so as to have the following weight ratio, and mixed until uniform to obtain an UV curable ink composition.
Polycarbonate skeleton urethane acrylate oligomer: 8% by weight
(Weight average molecular weight 5,000)
Polycaprolactone skeleton urethane acrylate oligomer: 8% by weight
(Weight average molecular weight 3,500)
Polyester skeleton urethane acrylate oligomer: 8% by weight
(Weight average molecular weight 3,500)
Phenoxyethyl acrylate: 8% by weight
Dicyclopentanyl acrylate: 5% by weight
N-vinylcaprolactam: 2% by weight
N, N-dimethylacrylamide: 5% by weight
N, N-butoxymethylacrylamide: 5% by weight
Photopolymerization initiator 1: 4% by weight
Photopolymerization initiator 2: 2% by weight
Photopolymerization initiator 3: 2% by weight
Pigment (carbon black / iron oxide): 20% by weight
Extender pigment: 18% by weight
Antifoaming agent (silicone): 1% by weight
Leveling agent (silicone): 1% by weight
Dispersant (carboxylic acid type): 3% by weight

In addition, the detail of the photoinitiators 1-3 mentioned above is as showing below.
(Photopolymerization initiator 1)
Chemical name: Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide / acyl phosphine oxide compounds Product name: BASF Corporation, Lucillin TPO

(Photopolymerization initiator 2)
Chemical name: oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone]
/ Α-Hydroxyketone compound trade name: manufactured by LAMBERTI, ESACURE KIP150

(Photopolymerization initiator 3)
Chemical name: 1- [4- (4-benzoylphenylsulfanyl) phenyl] -2-methyl-2- (4-methylphenylsulfonyl) propan-1-one / ketosulfone compound Product name: manufactured by LAMBERTI Corporation ESACURE1001M
Tables 1 and 2 show the composition ratios (% by weight) of all ultraviolet curable ink compositions prepared in the examples.

2. Evaluation of ultraviolet curable ink composition (1) Ultraviolet curable After printing an ultraviolet curable ink composition on a 0.5 mm thick transparent polycarbonate plate (Iupilon NF2000) under the following printing conditions, a UV irradiator ( UV curing was evaluated under the following curing conditions using GS Yuasa Lighting Co., Ltd. (CS-60).

(Printing conditions)
Printing plate: Polyester screen 300 mesh Emulsion film thickness: 8 μm
Cured coating film: 10 μm

(Curing conditions)
Metal halide lamp: 120 W / cm ² Double lamp height: 100 mm
Conveyor speed: 7m / min
Lamp peak intensity: 1.18 W / cm ²
Lamp integrated light intensity: 0.88 J / cm ²

That is, with respect to the obtained cured coating film, the pencil hardness was measured according to JIS K-5600 5.4, and the ultraviolet curability was evaluated from the following criteria. The obtained results are shown in Table 3.
A: Pencil hardness is F or more.
○: Pencil hardness is HB or more and less than F.
Δ: Pencil hardness is B or more and less than HB.
X: Pencil hardness is less than B.

(2) Adhesiveness The adhesiveness of the cured coating film obtained under the same conditions as in the evaluation of UV curable property was evaluated by a cross-cut cello tape (registered trademark) peel test according to JIS K-5600 5.6.
That is, on the cured coating film, a 100th grid was prepared using a cutter guide with a gap interval of 1 mm, and the adhesion was evaluated by the tape method in light of the following criteria. In addition, the evaluation result showed the number of the grid which was not peeled off expressed in%. The obtained results are shown in Table 3.
◎: The number of grids not peeled off is 99% or more ○: The number of grids not stripped is less than 95 to less than 99% Δ: The number of grids not stripped is less than 75 to less than 95% ×: The number of grids not stripped is 75 %Less than

(3) Warm water resistance Warm water resistance was evaluated by a cross-cut cello tape (registered trademark) peel test for a cured coating film obtained under the same conditions as in the evaluation of UV curability.
That is, a 100th grid is prepared on a cured coating film using a cutter guide having a gap interval of 1 mm, a hot water resistance test (immersed in warm water at 40 ° C. for 24 hours), and evaluated in accordance with the following criteria: did. The obtained results are shown in Table 3.
◎: The number of grids not peeled off is 99% or more ○: The number of grids not stripped is less than 95 to less than 99% Δ: The number of grids not stripped is less than 75 to less than 95% ×: The number of grids not stripped is 75 %Less than

(4) Impact resistance About the cured coating film obtained on the conditions similar to evaluation of ultraviolet sclerosis | hardenability, impact resistance was evaluated using the DuPont impact tester according to JISK-56005.3.
That is, for the obtained cured coating film, an impact test in which a 500 g weight was dropped from a height of 50 cm was measured by a DuPont impact tester, and evaluated according to the following criteria. The obtained results are shown in Table 3.
(Double-circle): There is no generation | occurrence | production of a crack and a crack at all.
○: Cracks and cracks hardly occur.
Δ: Some cracks and cracks occurred.
X: Peeling of the cured coating film occurred.

(5) Comprehensive evaluation The above-described ultraviolet curability, adhesion, hot water resistance and impact resistance were comprehensively evaluated.
That is, each evaluation in these test items was evaluated in light of the following criteria. The obtained results are shown in Table 3.
A: All are evaluations of A.
○: All are evaluations of ○ or more, and at least one evaluation of ○ exists.
Δ: At least one evaluation of Δ or less exists and x evaluation is 1 or less.
X: Two or more evaluations of x exist.

(6) VOC emission amount Further, the obtained cured coating film was measured for the emission amount of acetaldehyde, which is a VOC-regulated substance, when no after-baking treatment was performed.
That is, a printed product having a solid patch pattern of 100 mm × 100 mm was created on the printing substrate under the above-described printing and curing conditions.
Next, the obtained printed product was put in a sealed bag having a back capacity of 10 liters together with 5 liters of nitrogen gas, and kept at a temperature of 80 ° C. ± 3 ° C. for 2 hours.
Finally, the amount of acetaldehyde diffused (μg / 100 cm ² ) in the sealed bag was measured using gas chromatography (HP 6890 series, manufactured by Hewlett-Packard Co., Ltd.) and evaluated in accordance with the following criteria. Further, the amount of emission of formaldehyde, toluene, xylene, ethylbenzene, and styrene, which are other VOC regulated substances, was measured in the same manner as the amount of emission of acetaldehyde. Table 4 shows the obtained results.
A: The amount of acetaldehyde diffused is less than 4 μg / 100 cm ² .
A: The amount of acetaldehyde diffused is a value less than 4 to 6 μg / 100 cm ² .
(Triangle | delta): The amount of acetaldehyde diffused is a value below 6-8 microgram / 100cm < ² >.
×: Acetaldehyde emission is a value of 10 μg / 100 cm ² or more

[Example 2]
In Example 2, when preparing the UV curable ink composition, the polycarbonate skeleton urethane acrylate oligomer was 10% by weight, the polyester skeleton urethane acrylate oligomer was 6% by weight, the phenoxyethyl acrylate monomer was 10% by weight, and dicyclopenta The nyl acrylate monomer was changed to 3% by weight and, further, 2% by weight of isobornyl acrylate monomer was added and no N-vinylcaprolactam was added.
About other than that, while producing the ultraviolet curable ink composition similarly to Example 1, it evaluated. The obtained results are shown in Tables 3 and 4.

[Example 3]
In Example 3, when preparing the ultraviolet curable ink composition, 12 wt% of the polycarbonate skeleton urethane acrylate oligomer, 12 wt% of the polycaprolactone skeleton urethane acrylate oligomer, 10 wt% of the phenoxyethyl acrylate monomer, dicyclopenta The nyl acrylate monomer was changed to 4% by weight and N-vinylcaprolactam was changed to 1% by weight, and no polyester backbone urethane acrylate oligomer was added.
About other than that, while producing the ultraviolet curable ink composition similarly to Example 1, it evaluated. The obtained results are shown in Tables 3 and 4.

[Example 4]
In Example 4, when preparing the UV curable ink composition, the polycarbonate skeleton urethane acrylate oligomer was 6% by weight, the polycaprolactone skeleton urethane acrylate oligomer was 6% by weight, the polyester skeleton urethane acrylate oligomer was 6% by weight, phenoxyethyl. The acrylate monomer was changed to 9% by weight, the dicyclopentanyl acrylate monomer to 4% by weight, and the N-vinylcaprolactam to 5% by weight, and 3% by weight of the isobornyl acrylate monomer was added.
Other than that, an ultraviolet curable ink composition was prepared and evaluated in the same manner as in Example 1. The obtained results are shown in Tables 3 and 4.

[Example 5]
In Example 5, when the ultraviolet curable ink composition was prepared, the polycarbonate skeleton urethane acrylate oligomer was changed to 12% by weight, and the polyether skeleton urethane acrylate oligomer was further added by 12% by weight, and the polycaprolactone skeleton urethane acrylate oligomer was added. No polyester skeleton urethane acrylate oligomer was added.
About other than that, while producing the ultraviolet curable ink composition similarly to Example 1, it evaluated. The obtained results are shown in Tables 3 and 4.

[Example 6]
In Example 6, when preparing the ultraviolet curable ink composition, 5% by weight of the isobornyl acrylate monomer was added and no dicyclopentanyl acrylate monomer was added.
Other than that, an ultraviolet curable ink composition was prepared and evaluated in the same manner as in Example 1. The obtained results are shown in Tables 3 and 4.

[Example 7]
In Example 7, when producing the ultraviolet curable ink composition, the photopolymerization initiator 1 was changed to 8% by weight, and the photopolymerization initiator 2 and the photopolymerization initiator 3 were not added.
About other than that, while producing the ultraviolet curable ink composition similarly to Example 1, it evaluated. The obtained results are shown in Tables 3 and 4.

[Example 8]
In Example 8, when preparing the ultraviolet curable ink composition, the photopolymerization initiator 2 was changed to 4% by weight and the photopolymerization initiator 3 was changed to 4% by weight, and the photopolymerization initiator 1 was not added. .
About other than that, while producing the ultraviolet curable ink composition similarly to Example 1, it evaluated. The obtained results are shown in Tables 3 and 4.

[Comparative Example 1]
In Comparative Example 1, when preparing the UV curable ink composition, the polyether skeleton urethane acrylate oligomer was 8% by weight, the phenoxyethyl acrylate monomer was 5% by weight, the dicyclopentanyl acrylate monomer was 10% by weight, and photopolymerization was performed. Initiator 1 was changed to 6% by weight, and further, 10% by weight of isobornyl acrylate monomer was added, and polyester skeleton urethane acrylate oligomer, N-vinylcaprolactam, N, N-dimethylacrylamide, N, N-butoxymethylacrylamide, And no photoinitiator 3 was added.
About other than that, while producing the ultraviolet curable ink composition similarly to Example 1, it evaluated. The results obtained are shown in Tables 5 and 6.

[Comparative Example 2]
In Comparative Example 2, when preparing the ultraviolet curable ink composition, the phenoxyethyl acrylate monomer 3 wt%, the dicyclopentanyl acrylate monomer 8 wt%, and the photopolymerization initiator 1 were changed to 8 wt%, 8% by weight of the polyether skeleton urethane acrylate oligomer and 4% by weight of the isobornyl acrylate monomer were added, and the polycarbonate skeleton urethane acrylate oligomer, N-vinylcaprolactam, and photoinitiators 2 and 3 were not added.
About other than that, while producing the ultraviolet curable ink composition similarly to Example 1, it evaluated. The results obtained are shown in Tables 5 and 6.

[Comparative Example 3]
In Comparative Example 3, when preparing the UV curable ink composition, 5% by weight of the polycarbonate skeleton urethane acrylate oligomer, 4% by weight of the polycaprolactone skeleton urethane acrylate oligomer, 4% by weight of the polyester skeleton urethane acrylate oligomer, phenoxyethyl 6 wt% acrylate monomer, 4 wt% dicyclopentanyl acrylate monomer, 20 wt% N-vinylcaprolactam, 3 wt% N, N-dimethylacrylamide, and 3 wt% N, N-butoxymethylacrylamide Changed to.
About other than that, while producing the ultraviolet curable ink composition similarly to Example 1, it evaluated. The results obtained are shown in Tables 5 and 6.

[Comparative Example 4]
In Comparative Example 4, when preparing the UV curable ink composition, the dicyclopentanyl acrylate monomer was changed to 8% by weight, and the isobornyl acrylate monomer was further added by 5% by weight, and the phenoxyethyl acrylate monomer was added. There wasn't.
About other than that, while producing the ultraviolet curable ink composition similarly to Example 1, it evaluated. The results obtained are shown in Tables 5 and 6.

[Comparative Example 5]
In Comparative Example 5, in preparing the ultraviolet curable ink composition, the polycarbonate skeleton urethane acrylate oligomer was 9% by weight, the polycaprolactone skeleton urethane acrylate oligomer was 9% by weight, the polyester skeleton urethane acrylate oligomer was 9% by weight, and phenoxy. The ethyl acrylate monomer was changed to 10% by weight and no dicyclopentanyl acrylate monomer was added.
About other than that, while producing the ultraviolet curable ink composition similarly to Example 1, it evaluated. The results obtained are shown in Tables 5 and 6.

[Comparative Example 6]
In Comparative Example 6, when preparing the ultraviolet curable ink composition, the polycarbonate skeleton urethane acrylate oligomer was 10% by weight, the polycaprolactone skeleton urethane acrylate oligomer was 10% by weight, the polyester skeleton urethane acrylate oligomer was 10% by weight, phenoxyethyl. The acrylate monomer was changed to 10% by weight and the dicyclopentanyl acrylate monomer was changed to 7% by weight, and N, N-dimethylacrylamide and N, N-butoxymethylacrylamide were not added.
Other than that, an ultraviolet curable ink composition was prepared and evaluated in the same manner as in Example 1. The results obtained are shown in Tables 5 and 6.

  By using the ultraviolet curable ink composition of the present invention, it can be applied to an ultraviolet curable ink for screen printing, has excellent adhesion to a substrate and an ultraviolet curing speed, and is obtained by ultraviolet curing. It is possible to provide an ultraviolet curable ink composition that reduces the emission of VOC as a countermeasure against a sick house in consideration of the environmental protection of the manufacturing process and the Fire Service Law and the Labor Safety Law without subjecting the display to after-baking treatment. .

FIG. 1 is a diagram provided to explain the relationship between the amount of polycarbonate skeleton urethane acrylate oligomer added, the amount of acetaldehyde diffused, and the adhesion. FIG. 2 is a diagram provided to explain the relationship between the amount of (meth) acrylate monomer added, the amount of acetaldehyde diffused, and the adhesion. FIG. 3 is a diagram provided to explain the relationship between the amount of acrylamide compound added, the amount of acetaldehyde diffused, and the adhesion. FIG. 4 is a diagram provided to explain the relationship between the amount of N-vinylcaprolactam added, the amount of acetaldehyde emitted, and the adhesion.

Claims (9)

An ultraviolet curable ink composition in which the amount of N-vinylcaprolactam added as a curing component is 0% by weight or 15% by weight or less based on the total amount, and
As a curing component, a mixture of two or more urethane acrylate oligomers including a polycarbonate skeleton urethane acrylate oligomer having a weight average molecular weight of 2,500 to 10,000, a mixture of (meth) acrylate monomers including a phenoxyethyl acrylate monomer, An ultraviolet curable ink composition comprising an acrylamide compound.   As urethane acrylate oligomers other than the polycarbonate skeleton urethane acrylate oligomer, a polyester skeleton urethane acrylate oligomer having a weight average molecular weight of 2,000 to 15,000 and a polycaprolactone skeleton urethane acrylate having a weight average molecular weight of 2,000 to 15,000. The ultraviolet curable ink composition according to claim 1, comprising an oligomer or any one thereof.   The ultraviolet curable ink composition according to claim 1 or 2, wherein the addition amount of the polycarbonate skeleton urethane acrylate oligomer is set to a value within a range of 5 to 50% by weight with respect to the total amount.   The ultraviolet curable ink composition according to any one of claims 1 to 3, wherein the addition amount of the acrylamide compound is set to a value within a range of 1 to 35% by weight with respect to the total amount. .   The ultraviolet curable ink composition according to claim 1, further comprising a dicyclopentanyl acrylate monomer as the (meth) acrylate monomer.   The ultraviolet curable type according to any one of claims 1 to 5, wherein the addition amount of the (meth) acrylate monomer is set to a value within a range of 1 to 35% by weight with respect to the total amount. Ink composition.   While containing 2 or more types of photoinitiators as a photoinitiator of the said ultraviolet curable ink composition, the content of the said photoinitiator is 0.1-20 weight% with respect to the whole quantity. The ultraviolet curable ink composition according to claim 1, wherein the ultraviolet curable ink composition is a value within the range of 1 to 6.   The combination of an acyl phosphine oxide compound and an α-hydroxyketone compound, or a combination of an acyl phosphine oxide compound and a ketosulfone compound is used as the photopolymerization initiator. 8. The ultraviolet curable ink composition according to 7.   A printed display comprising a printed layer obtained from the ultraviolet curable ink composition according to claim 1.