Radiation-curable ink jet composition and ink jet method
A radiation-curable ink jet composition includes a polymerizable compound component including a monofunctional monomer component and a multifunctional monomer component, a photopolymerization initiator, and titanium oxide as a white color material. The content of the monofunctional monomer component is 90 mass % or more based on the total amount of the polymerizable compound component, and the weighted average of the glass transition temperatures of homopolymers of the respective polymerizable compounds is 48° C. or more when the mass ratios of the contents of the respective polymerizable compounds are weighted.
1. A radiation-curable ink jet composition comprising:
a polymerizable compound component including a monofunctional monomer component and a multifunctional monomer component;
a photopolymerization initiator; and
titanium oxide as a white color material, wherein
a content of the monofunctional monomer component is 90 mass % or more based on the total amount of the polymerizable compound component; and
a weighted average of glass transition temperatures of homopolymers of the respective polymerizable compounds is 48° C. or more and 65° C. or less when mass ratios of contents of the respective polymerizable compounds are weighted.
2. The radiation-curable ink jet composition according to claim 1 , wherein
a content of the titanium oxide is 15 mass % or more based on the total amount of the radiation-curable ink jet composition.
3. The radiation-curable ink jet composition according to claim 1 , wherein
the multifunctional monomer component includes a vinyl ether group-containing (meth)acrylate represented by formula (1):
CH 2 ═CR 1 —COOR 2 —O—CH═CH—R 3
where, R 1 is a hydrogen atom or a methyl group, R 2 is a divalent C2-C20 organic residue, and R 3 is a hydrogen atom or a monovalent C1-C11 organic residue.
4. The radiation-curable ink jet composition according to claim 1 , wherein
a content of the multifunctional monomer component is 0.10 to 10 mass % based on the total amount of the radiation-curable ink jet composition.
5. The radiation-curable ink jet composition according to claim 1 , wherein
the monofunctional monomer component includes a nitrogen-containing monofunctional monomer component.
6. The radiation-curable ink jet composition according to claim 5 , wherein
the nitrogen-containing monofunctional monomer component includes a monomer having a nitrogen-containing heterocyclic structure.
7. The radiation-curable ink jet composition according to claim 1 , wherein
the monofunctional monomer component includes a monofunctional (meth)acrylate having a crosslinked condensed ring structure.
8. The radiation-curable ink jet composition according to claim 7 , wherein
the monofunctional (meth)acrylate having a crosslinked condensed ring structure includes dicyclopentenyl (meth)acrylate.
9. An ink jet method using a liquid jet head that includes a nozzle for discharging the radiation-curable ink jet composition according to claim 1 , a pressure chamber to which the radiation-curable ink jet composition is supplied, and a circulation flow passage allowing the radiation-curable ink jet composition in the pressure chamber to circulate, the method comprising:
a discharging step of discharging the radiation-curable ink jet composition by the liquid jet head to adhere the composition to a recording medium, where the composition is previously heated; and
an irradiating step of irradiating the radiation-curable ink jet composition adhered to the recording medium with radioactive rays.
10. The ink jet method according to claim 9 , comprising:
a heating step of heating the radiation-curable ink jet composition in the liquid jet head to 40° C. or more.