Shrink film, container, and ink jet recording device

Abstract

To provide a shrink film in which a coating of radiation-curable ink is hardly broken when shrinking.SOLUTION: There is provided a shrink film that is heated to shrink in a first direction. The shrink film is rectangular having a first side and a second side along a first direction in plan view, and has, in plan view, a first region which has a contour including a part of the first side and a part of the second side, and where a coating of radiation-curable ink jet ink is formed and a second region which is in a rectangular shape having two opposed sides defined with the part of the first side and the part of the second side, and where the coating of the radiation-curable ink jet ink is not formed or a coating of the radiation-curable ink jet ink thinner than that in the first region is formed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a shrink film, a container, and an inkjet recording device. [Background technology]

[0002] Films are used as labels to be attached to containers made of resin, glass, metal, etc., in packaging products such as beverages, foods, seasonings, cosmetics, and daily necessities. Some of these films are attached by squeezing and adhering to the container by shrinking, and are called shrink films (shrinkable films). Shrink films are often printed according to the product, and the printing is usually done before the film is attached to the container, i.e., before it shrinks.

[0003] For example, Patent Document 1 discloses forming an image with a textured feel on a shrink film using ultraviolet-curable ink in an attempt to improve the impression of the label. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-152805 A Summary of the Invention [Problem to be solved by the invention]

[0005] There is a demand for inkjet printing technology onto shrink films that allows for low-cost, small-lot production. In addition, printing with radiation-curable inks is being considered because they offer higher image quality and better curing properties than water-based inks. However, coatings of radiation-curable inks printed on shrinking films can crack as the film shrinks. [Means for solving the problem]

[0006] One aspect of the shrink film according to the present invention is A shrink film that shrinks in a first direction when heated, The shrink film has a rectangular shape in a plan view having a first side and a second side along the first direction, The shrink film, in plan view, a first region having an outline including a part of the first side and a part of the second side, on which a coating of a radiation curable inkjet ink is formed; a second region having a rectangular shape with two opposing sides defined by a part of the first side and a part of the second side, in which a coating film of the radiation curable ink-jet ink is not formed or a coating film of the radiation curable ink-jet ink that is thinner than that of the first region is formed; has.

[0007] One aspect of the container according to the present invention is The shrink film is heat shrunk and placed around the outer periphery.

[0008] One aspect of the inkjet recording apparatus according to the present invention is to A head that ejects radiation curable inkjet ink; A control unit for controlling the head; having the control unit performs a recording mode in which the radiation curable inkjet ink is applied to a film that contracts in a first direction due to heating and has a rectangular shape in a plan view having a first side and a second side parallel to the first direction, In the recording mode, the control unit, in a plan view, a first region having an outline including a part of the first side and a part of the second side, on which a coating of a radiation curable inkjet ink is formed; a second region having a rectangular shape with two opposing sides defined by a part of the first side and a part of the second side, in which a coating film of the radiation curable ink-jet ink is not formed or a coating film of the radiation curable ink-jet ink that is thinner than that of the first region is formed; Form. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a schematic plan view of a shrink film according to an embodiment. [Diagram 2] Schematic diagrams showing a shrink film of an embodiment before and after shrinkage due to heat. [Diagram 3] Schematic diagram showing a conventional shrink film before and after shrinkage due to heat. [Figure 4] FIG. 1 is a perspective view of an inkjet recording apparatus capable of producing a shrink film according to an embodiment. [Diagram 5] FIG. 5 is a front view of the ultraviolet irradiation device shown in FIG. [Figure 6] AA arrow view of FIG. 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The following describes an embodiment of the present invention. The embodiment described below is an example of the present invention. The present invention is not limited to the following embodiment, and includes various modified forms that are implemented within the scope of the present invention. Note that not all of the configurations described below are necessarily essential configurations of the present invention.

[0011] 1. Shrink film The shrink film according to this embodiment is a shrink film that shrinks in a first direction when heated, and has a rectangular shape in a plan view having a first side and a second side along the first direction. The shrink film according to this embodiment also has, in a plan view, a first region in which a coating of a radiation curable inkjet ink is formed, and a second region in which no coating of the radiation curable inkjet ink is formed or a coating of the radiation curable inkjet ink that is thinner than the first region is formed.

[0012] 1.1. Shape and material of shrink film The shrink film of this embodiment is a film that shrinks in a first direction when heated. Fig. 1 is a schematic plan view of a shrink film 100 of this embodiment. The shrink film 100 shrinks along a first direction X when heated.

[0013] The shrink film 100 has a rectangular shape in plan view having a first side 101 and a second side 102 along a first direction X. The first side 101 and the second side do not need to be strictly straight lines or strictly parallel, but it is preferable that the first side 101 and the second side are parallel straight lines. Moreover, a rectangular shape refers to a shape surrounded by four sides. The shrink film 100 preferably has a parallelogram shape in plan view, and more preferably has a rectangular shape.

[0014] 1, the shrink film 100 has a rectangular shape in plan view having a third side 103 and a fourth side 104 that are perpendicular to the first direction X. Although not shown, the shrink film 100 may have a parallelogram shape in plan view having a third side and a fourth side that intersect with the first direction X.

[0015] The shrink film 100 is preferably a film that has the property of shrinking by 5% or more in the first direction X when heated to, for example, 80° C. The shrink film 100 more preferably shrinks by 10% or more in the first direction X when heated to 80° C., more preferably shrinks by 15% or more, and even more preferably shrinks by 30% or more. The temperature to which the shrink film 100 is heated to shrink it is not particularly limited.

[0016] The shrinkage rate when the shrink film 100 is heated can be calculated by the following formula. The shrinkage rate can be measured in any direction, and in this embodiment, the shrinkage rate in the first direction X may be within the above range. A stretched film obtained by stretching an unstretched film to orient the resin in the stretching direction has the property that, when heated, the stress due to the molecular orientation is relaxed and the film shrinks to the dimensions before stretching. The shrinkage rate and its direction can be adjusted, for example, by a stretching process when producing the shrink film 100, and the shrinkage direction is not particularly limited and may be the machine direction, the width direction, or both. Shrinkage rate (%) = (length before shrinkage - length after shrinkage) / length before shrinkage

[0017] The material of the shrink film 100 is not particularly limited, but examples thereof include polyolefin resins, polyester resins, polystyrene resins, and polyvinyl chloride resins. As an example, the polyester resin constituting the shrink film is one obtained by condensation polymerization of a dicarboxylic acid component and a polyhydric alcohol component.

[0018] The dicarboxylic acid component is not particularly limited, but examples thereof include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene-1,4- or -2,6-dicarboxylic acid, and 5-sodium sulfoisophthalic acid; ester-forming derivatives of aromatic dicarboxylic acids such as dialkyl esters and diaryl esters; and aliphatic dicarboxylic acids such as dimer acid, glutaric acid, adipic acid, sebacic acid, azelaic acid, oxalic acid, and succinic acid.

[0019] In addition, oxycarboxylic acids such as p-oxybenzoic acid, and polyvalent carboxylic acids such as trimellitic anhydride and pyromellitic anhydride may be used.

[0020] The polyhydric alcohol component is not particularly limited, but examples thereof include alkylene glycols such as ethylene glycol, diethylene glycol, dimer diol, propylene glycol, triethylene glycol, 1,4-butanediol, neopentyl glycol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 1,9-nonanediol, and 1,10-decanediol; ethylene oxide adducts of bisphenol compounds or derivatives thereof; trimethylolpropane, glycerin, pentaerythritol, polyoxytetramethylene glycol, and polyethylene glycol.

[0021] In addition, polyhydric alcohols such as trimethylolpropane, trimethylolethane, glycerin, diglycerin, and pentaerythritol may be used.

[0022] In addition, the polystyrene-based resin is not particularly limited, but examples thereof include polystyrene, poly(alkylstyrenes) such as poly(p-, m-, or o-methylstyrene), poly(2,4-, 2,5-, 3,4-, or 3,5-dimethylstyrene), and poly(p-tertiary butylstyrene), poly(halogenated styrenes) such as poly(p-, m-, or o-chlorostyrene), poly(p-, m-, or o-bromostyrene), poly(p-, m-, or o-fluorostyrene), and poly(o-methyl-p-fluorostyrene), poly(p-, m-, or o-chlorostyrene), poly(p-, m-, or o-bromostyrene), poly(p-, m-, or o-fluorostyrene), and poly(o-methyl-p-fluorostyrene), Examples of the poly(alkyl ether styrene) include poly(halogen-substituted alkyl styrene)s such as poly(methylstyrene), poly(alkoxy styrene)s such as poly(p-, m-, or o-methoxystyrene) and poly(p-, m-, or o-ethoxystyrene), poly(carboxyalkyl styrene)s such as poly(p-, m-, or o-carboxymethylstyrene), poly(alkyl ether styrene)s such as poly(p-vinylbenzyl propyl ether), poly(alkylsilyl styrene)s such as poly(p-trimethylsilylstyrene), and further, poly(vinylbenzyl dimethoxy phosphide).

[0023] The shrink film 100 may contain a rubber component. Examples of such rubber components include, but are not limited to, rubber in which the butadiene portion of a styrene-butadiene block copolymer is partially or completely hydrogenated, styrene-butadiene copolymer rubber, styrene-isoprene block copolymer, rubber in which the butadiene portion of a styrene-isoprene block copolymer is partially or completely hydrogenated, methyl acrylate-butadiene-styrene copolymer rubber, methyl methacrylate-alkyl acrylate-butadiene-styrene copolymer rubber, and the like.

[0024] Of these, it is more preferable that the material of the shrink film 100 contains polyethylene terephthalate (PET), which makes it easier to obtain a larger amount of shrinkage.

[0025] The shrink film 100 is preferably a stretched film. The stretching process may be either uniaxial stretching or biaxial stretching. The stretching method is not particularly limited, but may be, for example, a method having a stretching step in which an unstretched film is stretched 2.0 to 8.0 times, preferably 2.5 to 6.0 times, in a direction to give shrinkability (first direction X) in a temperature range of Tg-20°C to Tg+40°C based on the glass transition temperature (Tg) of the resin constituting the shrink film 100. After the stretching step, the film may be heat-treated at a temperature of 50 to 110°C while being stretched by 0 to 15% or relaxed by 0 to 15%.

[0026] 1.2.First area The shrink film 100 has an outline that includes a part of the first side 101 and a part of the second side 102, and has a first region 110 in which a coating 112 of a radiation curable inkjet ink is formed. In the example shown in Fig. 1, the shrink film 100 has two first regions 110 formed. The first region 110 may be formed in one location, or in three or more locations, as long as the second region 120 described below can be formed.

[0027] In the illustrated example, the outline of the first region 110 on the left side is a rectangle made up of a side common to the second region 120, the third side 103 of the shrink film 100, a portion 101b of the first side 101, and a portion 102b of the second side 102. Similarly, the outline of the first region 110 on the right side is a rectangle made up of a side common to the second region 120, the fourth side 104 of the shrink film 100, a portion 101a of the first side 101, and a portion 102a of the second side 102.

[0028] The length of the first side 101 constituting the outline of the first region 110 is not particularly limited, but is preferably 70% to 95% of the length of the first side 101, more preferably 80% to 85%, and even more preferably 85% to 90%. The same applies to the length of the second side 102 constituting the outline of the first region 110. In addition, when a plurality of first regions 110 are formed, it is preferable that the total length of the first side 101 or the second side 102 constituting the outline of each first region 110 is within the above range. That is, in the illustrated example, it is preferable that the sum of the lengths of the portions 101a and 101b of the first side 101 is within the above range, and it is preferable that the sum of the lengths of the portions 102a and 102b of the second side 102 is within the above range.

[0029] A coating 112 of radiation curable inkjet ink is formed over the entire first region 110. In the illustrated example, the shrink film 100 has an image 114 formed in the first region 110 by the coating 112 of radiation curable inkjet ink. The formation of the image 114 can improve the design of the shrink film 100 as a label. An image refers to something that can be visually recognized, such as a figure, a design, a letter, or a symbol.

[0030] The film thickness of the coating 112 of the radiation curable inkjet ink in the first region 110 is 5 μm or more, preferably 10 μm or more, and more preferably 15 μm or more. On the other hand, there is no particular upper limit to the film thickness of the coating 112 of the radiation curable inkjet ink in the first region 110, but it is preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 200 μm or less.

[0031] If the thickness of the coating 112 in the first region 110 is within this range, the first region 110 is less likely to shrink, and cracking of the coating 112 of the radiation curable inkjet ink formed in the first region 110 can be further suppressed.

[0032] 1.3.Second area The shrink film 100 has a rectangular shape with two opposing sides defined by a part of a first side 101 and a part of a second side 102, and has a second region 120 in which no coating of radiation curable inkjet ink is formed or in which a coating of radiation curable inkjet ink that is thinner than that in the first region is formed. In the example shown in Fig. 1, the shrink film 100 has one second region 120 formed. The second region 120 may be formed in two or more locations.

[0033] The length of the first side 101 constituting the outline of the second region 120 is not particularly limited, but is preferably 2% to 30% of the length of the first side 101, more preferably 5% to 20%, and even more preferably 5% to 15%. In other words, the length of the second region 120 in the first direction X is preferably 1 / 50 to 3 / 10 of the length of the shrink film 100 in the first direction X, more preferably 1 / 20 to 1 / 5, and even more preferably 1 / 20 to 15 / 100. The same applies to the length of the second side 102 constituting the outline of the second region 120. In addition, when a plurality of second regions 120 are formed, it is preferable that the total length of the first side 101 or the second side 102 constituting the outline of each second region 120 is within the above range.

[0034] When the length of the second region 120 in the first direction X is within the above range, cracking of the coating film 112 of the radiation curable inkjet ink formed in the first region 110 can be suppressed, and a sufficient amount of shrinkage can be obtained.

[0035] In the second region 120, either no coating of radiation curable inkjet ink is formed, or a coating of radiation curable inkjet ink that is thinner than that in the first region 110 is formed. In the example of Fig. 1, in the second region 120, no coating of radiation curable inkjet ink is formed.

[0036] In the second region 120, no coating of the radiation curable inkjet ink is formed, or a coating of the radiation curable inkjet ink that is thinner than that in the first region 110 is formed, so that the second region 120 shrinks preferentially compared to the first region 110, and cracking of the coating 112 of the radiation curable inkjet ink formed in the first region 110 can be suppressed. In particular, when no coating of the radiation curable inkjet ink is formed in the second region 120, this effect is more remarkable.

[0037] When a coating film of radiation curable ink-jet ink is formed in the second region 120, the thickness of the coating film is 5 μm or less, preferably 3 μm or less, and more preferably 2 μm or less. On the other hand, when a coating film of radiation curable ink-jet ink is formed in the second region 120, the lower limit of the thickness is not particularly limited, but is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more. This makes it possible for the second region 120 to shrink more easily than the first region 110, even if a coating film of radiation curable ink-jet ink is formed in the second region 120, and cracking of the coating film 112 of the radiation curable ink-jet ink formed in the first region 110 can be suppressed.

[0038] 1.4. Radiation-curable inkjet ink The radiation-curable inkjet ink is cured by irradiating it with radiation. Examples of radiation include ultraviolet light, electron beams, infrared light, visible light, X-rays, etc. As the radiation, ultraviolet light is preferred because radiation sources are readily available and widely used, and materials suitable for curing by ultraviolet radiation are readily available and widely used.

[0039] The components contained in the radiation curable inkjet ink are not particularly limited, but may include, for example, a polymerizable compound, a polymerization initiator, a polymerization inhibitor, a sensitizer, a surfactant, a coloring material, and a dispersant. It is not necessary for the radiation curable inkjet ink to contain all of these components, and it may contain only some of them. The components that may be contained in the radiation curable inkjet ink are described below.

[0040] (1) Polymerizable compound Those having a polymerizable functional group are generally called polymerizable compounds. The polymerizable compound may include a monofunctional monomer having one polymerizable functional group and a polyfunctional monomer having multiple polymerizable functional groups. The polymerizable compound may be used alone or in combination of two or more kinds.

[0041] The weighted average of the glass transition temperature of the polymerizable compound contained in the radiation curable inkjet ink is 20 to 70° C., preferably 25 to 65° C., more preferably 30 to 60° C., and even more preferably 40 to 50° C. When the weighted average of the glass transition temperature is 20° C. or higher, blocking resistance is further improved. Furthermore, when the weighted average of the glass transition temperature is 20° C. or higher, curability also tends to be further improved. Furthermore, when the weighted average of the glass transition temperature is 70° C. or lower, cracking can be more unlikely to occur.

[0042] The "glass transition temperature of the polymerizable compound" means the glass transition temperature of a homopolymer of the polymerizable compound. The weighted average glass transition temperature of the polymerizable compound can be adjusted by the glass transition temperature of the homopolymer of the polymerizable compound used and the content mass ratio of the polymerizable compound used.

[0043] Here, a method for calculating the weighted average of the glass transition temperatures of homopolymers in a polymerizable compound will be described. The weighted average of the glass transition temperatures of the homopolymers is called Tg All The glass transition temperature of the homopolymer of each polymerizable compound is Tg N The content mass ratio of the polymerizable compound is X N (wt%). N is a number starting from 1 according to the type of polymerizable compound contained in the radiation curable inkjet ink. For example, if three types of polymerizable compounds are used, the Tg 1 , Tg 2 , Tg 3 The weighted average Tg of the homopolymer glass transition temperature occurs. All is the glass transition temperature (Tg) of the homopolymer calculated for each polymerizable compound. N and the mass ratio X N Therefore, the following formula (1) holds. Tg All =Σ(Tg N X N ) ···(1)

[0044] The glass transition temperature of a homopolymer of a polymerizable compound can be measured by differential scanning calorimetry (DSC) in accordance with JIS K 7121. For example, a measuring device such as a "DSC6220" manufactured by Seiko Electronics Co., Ltd. can be used, and a sample can be one in which a monomer has been polymerized to such an extent that the glass transition temperature of the homopolymer becomes constant.

[0045] The content of the polymerizable compound is preferably from 55% by mass to 85% by mass, more preferably from 60% by mass to 80% by mass, and even more preferably from 65% by mass to 75% by mass, based on the total amount of the radiation-curable inkjet ink. When the content of the polymerizable compound is within the above range, blocking resistance or curability tends to be improved.

[0046] (1-1) Monofunctional Monomer The monofunctional monomer is not particularly limited, and examples thereof include nitrogen-containing monofunctional monomers, aromatic group-containing monofunctional monomers, monofunctional monomers having an alicyclic structure, etc. In place of or in addition to these, other monofunctional monomers may be included as necessary.

[0047] The content of the monofunctional monomer is preferably 30% by mass or more, more preferably 40% by mass or more, based on the total amount of the polymerizable compound. When the content of the monofunctional monomer is 30% by mass or more, blocking resistance tends to be further improved.

[0048] Examples of monofunctional monomers are given below, but the present invention is not limited to these.

[0049] (1-1-1) Nitrogen-containing monofunctional monomer The polymerizable compound preferably contains a nitrogen-containing monofunctional monomer, which tends to improve the adhesion of the resulting coating film and the blocking resistance.

[0050] The nitrogen-containing monofunctional monomer is not particularly limited, and examples thereof include nitrogen-containing monofunctional vinyl monomers such as N-vinylcaprolactam (n-VC), N-vinylformamide, N-vinylcarbazole, N-vinylacetamide, vinylmethyloxazolidinone (VMOX), and N-vinylpyrrolidone; nitrogen-containing monofunctional acrylate monomers such as acryloylmorpholine (ACMO); and nitrogen-containing monofunctional acrylamide monomers such as (meth)acrylamide, N-hydroxymethyl(meth)acrylamide, diacetone acrylamide, N,N-dimethyl(meth)acrylamide, and dimethylaminoethyl acrylate benzyl chloride quaternary salt.

[0051] Among these, it is preferable to include either a nitrogen-containing monofunctional vinyl monomer or a nitrogen-containing monofunctional acrylate monomer, more preferably a monomer having a nitrogen-containing heterocyclic structure such as vinylmethyloxazolidinone, acryloylmorpholine, or N-vinylcaprolactam, and even more preferably to include vinylmethyloxazolidinone. By including such a nitrogen-containing monofunctional monomer, the viscosity of the ink composition is further reduced, so that the ejection stability tends to be further improved. In addition, by including such a nitrogen-containing monofunctional monomer, the blocking resistance, shrink property, or curing property tends to be further improved. Furthermore, since vinylmethyloxazolidinone is a monomer with a low viscosity at room temperature, by including vinylmethyloxazolidinone, the ejection stability tends to be further improved.

[0052] The content of the nitrogen-containing monofunctional monomer is preferably from 15% by mass to 45% by mass, more preferably from 20% by mass to 40% by mass, and even more preferably from 25% by mass to 35% by mass, based on the total amount of the radiation-curable inkjet ink. By having the content of the nitrogen-containing monofunctional monomer within the above range, blocking resistance or curability tends to be further improved.

[0053] (1-1-2) Aromatic group-containing monofunctional monomer The aromatic group-containing monofunctional monomer is not particularly limited, but examples thereof include phenoxyethyl (meth)acrylate (PEA), benzyl (meth)acrylate, alkoxylated 2-phenoxyethyl (meth)acrylate, ethoxylated nonylphenyl (meth)acrylate, alkoxylated nonylphenyl (meth)acrylate, p-cumylphenol EO-modified (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate.

[0054] Among these, phenoxyethyl (meth)acrylate and benzyl (meth)acrylate are preferred, phenoxyethyl (meth)acrylate is more preferred, and phenoxyethyl acrylate (PEA) is even more preferred. By using such aromatic group-containing monofunctional monomers, the solubility of the polymerization initiator is improved, and the curability of the ink composition tends to be improved. In particular, when an acylphosphine oxide-based polymerization initiator or a thioxanthone-based polymerization initiator is used, the solubility tends to be good.

[0055] The content of the aromatic group-containing monofunctional monomer is preferably from 25% by mass to 55% by mass, more preferably from 30% by mass to 50% by mass, and even more preferably from 35% by mass to 45% by mass, based on the total amount of the radiation-curable inkjet ink. By having the content of the aromatic group-containing monofunctional monomer within the above range, blocking resistance or curability tends to be further improved.

[0056] (1-1-3) Monofunctional monomers having an alicyclic structure The monofunctional monomer having an alicyclic structure is not particularly limited, but examples thereof include monomers having a monocyclic hydrocarbon group such as tert-butylcyclohexanol (meth)acrylate (TBCHA), 3,3,5-trimethylcyclohexyl (meth)acrylate (TMCHA), and 2-(meth)acrylic acid-1,4-dioxaspiro[4,5]dec-2-ylmethyl; monomers having an unsaturated polycyclic hydrocarbon group such as dicyclopentenyl (meth)acrylate and dicyclopentenyloxyethyl (meth)acrylate; and monomers having a saturated polycyclic hydrocarbon group such as dicyclopentanyl (meth)acrylate and isobornyl (meth)acrylate (IBXA).

[0057] Among these, isobornyl (meth)acrylate, tert-butylcyclohexanol acrylate, and trimethylcyclohexyl (meth)acrylate are preferred, and isobornyl acrylate is more preferred. By using such a monofunctional monomer having an alicyclic structure, blocking resistance or curability tends to be further improved.

[0058] Furthermore, the content of the monofunctional monomer having an alicyclic structure is preferably from 15% by mass to 45% by mass, more preferably from 20% by mass to 40% by mass, and even more preferably from 25% by mass to 35% by mass, relative to the total amount of the radiation curable inkjet ink. By having the content of the monofunctional monomer having an alicyclic structure within the above range, blocking resistance or curability tends to be further improved.

[0059] (1-2) Polyfunctional Monomer The polyfunctional monomer is not particularly limited, but examples thereof include vinyl group-containing (meth)acrylate and polyfunctional (meth)acrylate. The polyfunctional monomer is not limited to these, and multiple types may be used. By including a polyfunctional monomer, the curing property of the coating film is more excellent. Generally, a coating film with excellent curing property is easily cracked during thermal shrinkage. Therefore, when a polyfunctional monomer is included, the effect of suppressing the coating film of the present invention from cracking is more remarkable than when a polyfunctional monomer is not included.

[0060] The content of the polyfunctional monomer in the radiation curable inkjet ink is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass, based on the total amount of the polymerizable compounds. When the content of the polyfunctional monomer is within such a range, the curability or blocking resistance of the coating film is further improved. Examples of the polyfunctional monomer are given below, but are not limited thereto.

[0061] (1-2-1) Vinyl group-containing (meth)acrylate The vinyl group-containing (meth)acrylate is not particularly limited, but examples thereof include compounds represented by the following formula (I): By including such a vinyl group-containing (meth)acrylate, blocking resistance, shrink properties, or curability tend to be further improved. H2C=CR 1 -CO-OR 2 -O-CH=CH-R 3 (I) (In the formula, R 1 is a hydrogen atom or a methyl group, R 2 is a divalent organic residue having 2 to 20 carbon atoms, and R 3 is a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms.

[0062] In the above formula (I), R 2 Examples of the divalent organic residue having 2 to 20 carbon atoms represented by the formula (I) include a linear, branched or cyclic alkylene group having 2 to 20 carbon atoms which may be substituted, an alkylene group having 2 to 20 carbon atoms which may be substituted and which has an oxygen atom due to an ether bond and / or an ester bond in the structure, and a divalent aromatic group having 6 to 11 carbon atoms which may be substituted. Among these, alkylene groups having 2 to 6 carbon atoms such as an ethylene group, an n-propylene group, an isopropylene group, and a butylene group, and alkylene groups having 2 to 9 carbon atoms which have an oxygen atom due to an ether bond in the structure such as an oxyethylene group, an oxyn-propylene group, an oxyisopropylene group, and an oxybutylene group are preferred. Furthermore, from the viewpoint of further reducing the viscosity of the ink composition and further improving the curability of the ink composition, R 2 is an alkylene group having 2 to 9 carbon atoms and having an oxygen atom by an ether bond in the structure, such as an oxyethylene group, an oxy-n-propylene group, an oxyisopropylene group, or an oxybutylene group, more preferably a compound having a glycol ether chain.

[0063] In the above formula (I), R 3The monovalent organic residue having 1 to 11 carbon atoms, represented by the formula (I), is preferably a linear, branched or cyclic alkyl group having 1 to 11 carbon atoms, which may be substituted, or an aromatic group having 6 to 11 carbon atoms, which may be substituted. Among these, more preferred are alkyl groups having 1 to 2 carbon atoms, such as a methyl group or an ethyl group, and aromatic groups having 6 to 8 carbon atoms, such as a phenyl group and a benzyl group.

[0064] When each of the organic residues is a group that may be substituted, the substituent is divided into a group that contains carbon atoms and a group that does not contain carbon atoms.First, when the substituent is a group that contains carbon atoms, the carbon atom is counted in the number of carbon atoms of the organic residue.As the group that contains carbon atoms, but is not limited to the following, for example, a carboxyl group and an alkoxy group can be mentioned.Next, as the group that does not contain carbon atoms, but is not limited to the following, for example, a hydroxyl group and a halo group can be mentioned.

[0065] Specific examples of the compound of formula (I) include, but are not limited to, 2-vinyloxyethyl (meth)acrylate, 3-vinyloxypropyl (meth)acrylate, 1-methyl-2-vinyloxyethyl (meth)acrylate, 2-vinyloxypropyl (meth)acrylate, 4-vinyloxybutyl (meth)acrylate, 1-methyl-3-vinyloxypropyl (meth)acrylate, 1-vinyloxymethylpropyl (meth)acrylate, 2-methyl-3-vinyloxypropyl (meth)acrylate, 1,1-dimethyl-2-vinyloxypropyl (meth)acrylate, dimethylethyl, 3-vinyloxybutyl (meth)acrylate, 1-methyl-2-vinyloxypropyl (meth)acrylate, 2-vinyloxybutyl (meth)acrylate, 4-vinyloxycyclohexyl (meth)acrylate, 6-vinyloxyhexyl (meth)acrylate, 4-vinyloxymethylcyclohexylmethyl (meth)acrylate, 3-vinyloxymethylcyclohexylmethyl (meth)acrylate, 2-vinyloxymethylcyclohexylmethyl (meth)acrylate, p-vinyloxymethylphenylmethyl (meth)acrylate, (meth)acrylate m-vinyloxymethylphenylmethyl (meth)acrylate, o-vinyloxymethylphenylmethyl (meth)acrylate, 2-(2-vinyloxyethoxy)ethyl (meth)acrylate, 2-(2-vinyloxyethoxy)ethyl acrylate (VEEA), 2-(vinyloxyisopropoxy)ethyl (meth)acrylate, 2-(vinyloxyethoxy)propyl (meth)acrylate, 2-(vinyloxyethoxy)isopropyl (meth)acrylate, 2-(vinyloxyisopropoxy)propyl (meth)acrylate, 2-(vinyloxyisopropoxy)propyl (meth)acrylate, (meth)acrylic acid 2-(vinyloxyethoxyethoxy)ethyl, (meth)acrylic acid 2-(vinyloxyethoxyisopropoxy)ethyl, (meth)acrylic acid 2-(vinyloxyisopropoxyethoxy)ethyl, (meth)acrylic acid 2-(vinyloxyisopropoxyisopropoxy)ethyl, (meth)acrylic acid 2-(vinyloxyethoxyethoxy)propyl, (meth)acrylic acid 2-(vinyloxyethoxyisopropoxy)propyl, (meth)acrylic acid 2-(vinyloxyisopropoxyethoxy)propyl, (meth)acrylic acid 2-(vinyloxyisopropoxyethoxy)propyl,2-(vinyloxyisopropoxyisopropoxy)propyl (meth)acrylate, 2-(vinyloxyethoxyethoxy)isopropyl (meth)acrylate, 2-(vinyloxyethoxyisopropoxy)isopropyl (meth)acrylate, 2-(vinyloxyethoxyisopropoxy)isopropyl (meth)acrylate, 2-(vinyloxyisopropoxyethoxy)isopropyl (meth)acrylate, 2-(vinyloxyisopropoxyisopropoxy)isopropyl (meth)acrylate, 2-(vinyloxyethoxyethoxyethoxy)ethyl (meth)acrylate, 2-(vinyloxy 2-(isopropenoxyethoxyethoxyethoxy)ethyl (meth)acrylate, 2-(isopropenoxyethoxy)ethyl (meth)acrylate, 2-(isopropenoxyethoxyethoxy)ethyl (meth)acrylate, 2-(isopropenoxyethoxyethoxy)ethyl (meth)acrylate, 2-(isopropenoxyethoxyethoxyethoxy)ethyl (meth)acrylate, polyethylene glycol monovinyl ether (meth)acrylate, and polypropylene glycol monovinyl ether (meth)acrylate. Of these specific examples, 2-(2-vinyloxyethoxy)ethyl acrylate is particularly preferred in that it is easy to balance the curability and viscosity of the radiation-curable inkjet ink.

[0066] The content of the vinyl group-containing (meth)acrylate is preferably from 1.0 to 10% by mass, more preferably from 2.0 to 8.0% by mass, and even more preferably from 4.0 to 6.0% by mass, based on the total amount of the radiation-curable inkjet ink. By having the content of the vinyl group-containing (meth)acrylate within the above range, blocking resistance, shrink properties, or curability tend to be further improved.

[0067] (1-2-2) Polyfunctional (meth)acrylate The polyfunctional (meth)acrylate is not particularly limited, and examples thereof include dipropylene glycol di(meth)acrylate (DPGDA), diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipropylene glycol dimethacrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate, EO (ethylene oxide) adduct di(meth)acrylate of bisphenol A, PO(propylene oxide) di(meth)acrylate of bisphenol A, and the like. bifunctional (meth)acrylates such as ethylene oxide) adduct di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, and polytetramethylene glycol di(meth)acrylate; and trifunctional or higher polyfunctional (meth)acrylates such as trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, glycerin propoxy tri(meth)acrylate, caprolactone-modified trimethylolpropane tri(meth)acrylate, pentaerythritol ethoxy tetra(meth)acrylate, and caprolactam-modified dipentaerythritol hexa(meth)acrylate.

[0068] Among these, dipropylene glycol diacrylate (DPGDA) is more preferable. By using such a polyfunctional (meth)acrylate, the curability and abrasion resistance tend to be further improved and the viscosity tends to be further reduced.

[0069] The content of the polyfunctional (meth)acrylate is preferably 2.5% by mass or more and 17.5% by mass or less, more preferably 5.0% by mass or more and 15% by mass or less, and even more preferably 7.5% by mass or more and 12.5% ​​by mass or less, based on the total amount of the ink composition. When the content of the polyfunctional (meth)acrylate is within the above range, the curability is improved and the viscosity tends to be reduced.

[0070] (2) Polymerization initiator The polymerization initiator is not particularly limited as long as it is a photopolymerization initiator that generates active species by irradiation with radiation, and examples thereof include known polymerization initiators such as acylphosphine oxide-based polymerization initiators, alkylphenone-based polymerization initiators, titanocene-based polymerization initiators, and thioxanthone-based polymerization initiators. Among these, acylphosphine oxide-based polymerization initiators and thioxanthone-based polymerization initiators are preferred, and acylphosphine oxide-based polymerization initiators are more preferred. By using such a polymerization initiator, the curability of the radiation-curable inkjet ink tends to be further improved. The polymerization initiator may be used alone or in combination of two or more types.

[0071] The content of the polymerization initiator is preferably from 2.5% by mass to 17.5% by mass, more preferably from 5% by mass to 15% by mass, and even more preferably from 7.5% by mass to 12.5% ​​by mass, based on the total amount of the radiation curable inkjet ink. By having the content of the polymerization initiator within the above range, the curability of the composition tends to be further improved.

[0072] The acylphosphine oxide polymerization initiator is not particularly limited, but examples thereof include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and the like.

[0073] Examples of commercially available acylphosphine oxide polymerization initiators include, but are not limited to, Omnirad 819 (bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide), IRGACURE 1800 (a mixture of bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and 1-hydroxy-cyclohexyl-phenyl ketone in a mass ratio of 25:75), Speedcure TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide), and the like.

[0074] (3) Sensitizer The radiation curable inkjet ink may contain a sensitizer. Examples of the sensitizer include, but are not limited to, thioxanthone-based compounds. Examples of the thioxanthone-based compounds include, but are not limited to, thioxanthone, diethylthioxanthone, isopropylthioxanthone, and chlorothioxanthone.

[0075] Commercially available thioxanthone polymerization initiators include, but are not limited to, Speedcure DETX (2,4-diethylthioxanthen-9-one), Speedcure ITX (2-isopropylthioxanthone) (both manufactured by Lambson Chemical), and KAYACURE DETX-S (2,4-diethylthioxanthone) (manufactured by Nippon Kayaku Co., Ltd.).

[0076] When a sensitizer is contained, the content thereof is preferably 0.5% by mass or more and 7.5% by mass or less, more preferably 1.5% by mass or more and 5.0% by mass or less, and even more preferably 2.5% by mass or more and 3.5% by mass or less, based on the total amount of the radiation curable inkjet ink. By having the content of the sensitizer within the above range, the curability of the composition tends to be further improved.

[0077] (4) Polymerization inhibitors The radiation curable inkjet ink may contain a polymerization inhibitor, which may include, but is not limited to, p-methoxyphenol, hydroquinone monomethyl ether (MEHQ), 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, hydroquinone, cresol, t-butylcatechol, 3,5-di-t-butyl-4-hydroxytoluene, 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-butylphenol), and 4,4'-thiobis(3-methyl-6-t-butylphenol), hindered amine compounds, 2,2,6,6-tetramethylpiperidinyl-1-oxyl, 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl (LA-7RD), or derivatives of 2,2,6,6-tetramethylpiperidinyl-1-oxyl.

[0078] When a polymerization inhibitor is contained, its content is preferably from 0.1% by mass to 0.7% by mass, more preferably from 0.2% by mass to 0.5% by mass, based on the total amount of the radiation curable inkjet ink. By having the content of the polymerization inhibitor within the above range, the storage stability of the radiation curable inkjet ink tends to be further improved.

[0079] (5) Surfactants The radiation curable inkjet ink may contain a surfactant. The surfactant is not particularly limited, but examples thereof include acetylene glycol surfactants, fluorine-based surfactants, and silicone-based surfactants.

[0080] Examples of acetylene glycol surfactants include, but are not limited to, alkylene oxide adducts of 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 2,4,7,9-tetramethyl-5-decyne-4,7-diol, and alkylene oxide adducts of 2,4-dimethyl-5-decyne-4-ol and 2,4-dimethyl-5-decyne-4-ol.

[0081] The fluorine-based surfactant is not particularly limited, but examples thereof include perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl phosphate, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl betaine, and perfluoroalkyl amine oxide compound.

[0082] Examples of silicone surfactants include polysiloxane compounds, polyester-modified silicones, polyether-modified organosiloxanes, etc. Examples of polyester-modified silicones include BYK-347, 348, BYK-UV3500, 3510, and 3530 (all manufactured by BYK Additives & Instruments), etc. Examples of polyether-modified silicones include BYK-3570 (manufactured by BYK Additives & Instruments), etc.

[0083] When a surfactant is contained, its content is preferably from 0.1% to 1.0% by mass, more preferably from 0.2% to 0.8% by mass, based on the total mass of the radiation curable inkjet ink. By having the surfactant content within the above range, the wettability of the radiation curable inkjet ink tends to be further improved.

[0084] (6) Coloring materials The radiation curable inkjet ink may further contain a coloring material, which allows the radiation curable inkjet ink to be used as a colored ink.

[0085] When the radiation-curable inkjet ink contains a coloring material, the coating film can form an image with better color. When the radiation-curable inkjet ink contains a coloring material, it is more preferable to select the coloring material so that the coating film is opaque. In this way, it is easier to conceal the object of the label, i.e., the packaged product, using the shrink film 100.

[0086] The coloring material may be at least one of a pigment and a dye. Examples of the coloring material that may be used are given below.

[0087] As the inorganic pigment, carbon blacks such as furnace black, lamp black, acetylene black, and channel black (CI (Colour Index Generic Name) Pigment Black 7), iron oxide, and titanium oxide can be used.

[0088] Examples of organic pigments include azo pigments such as insoluble azo pigments, condensed azo pigments, azo lakes, and chelate azo pigments; polycyclic pigments such as phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments; dye chelates (e.g., basic dye chelates, acid dye chelates, etc.); dye lakes (basic dye lakes, acid dye lakes), nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments.

[0089] The total content of coloring materials can be appropriately changed depending on the purpose, but is preferably 0.5% by mass or more and 15% by mass or less, more preferably 1.0% by mass or more and 10% by mass or less, and even more preferably 1.5% by mass or more and 5.0% by mass or less, based on the total amount of the radiation curable inkjet ink. The radiation curable inkjet ink may be a clear ink that does not contain coloring materials or contains coloring materials to an extent that coloring is not intended (for example, 0.1% by mass or less).

[0090] The dye is not particularly limited, but examples thereof include acid dyes such as CI Acid Yellow, CI Acid Red, CI Acid Blue, CI Acid Orange, CI Acid Violet, and CI Acid Black; basic dyes such as CI Basic Yellow, CI Basic Red, CI Basic Blue, CI Basic Orange, CI Basic Violet, and CI Basic Black; direct dyes such as CI Direct Yellow, CI Direct Red, CI Direct Blue, CI Direct Orange, CI Direct Violet, and CI Direct Black; reactive dyes such as CI Reactive Yellow, CI Reactive Red, CI Reactive Blue, CI Reactive Orange, CI Reactive Violet, and CI Reactive Black; and disperse dyes such as CI Disperse Yellow, CI Disperse Red, CI Disperse Blue, CI Disperse Orange, CI Disperse Violet, and CI Disperse Black. The above dyes may be used alone or in combination of two or more.

[0091] (7) Other ingredients The radiation curable inkjet ink may further contain additives such as coloring materials such as pigments and dyes, and dispersants for pigments and the like, as required.

[0092] (8) Properties and production of radiation-curable inkjet inks In view of being applied by an inkjet method, the radiation curable inkjet ink preferably has a viscosity at 20°C of 1.5 mPa·s or more and 15 mPa·s or less, more preferably 1.5 mPa·s or more and 7 mPa·s or less, and even more preferably 1.5 mPa·s or more and 5.5 mPa·s or less.

[0093] From the viewpoint of ensuring appropriate wetting and spreading properties on the shrink film, the radiation-curable inkjet ink has a surface tension of 40 mN / m or less, preferably 38 mN / m or less, and more preferably 35 mN / m or less at 25° C. The surface tension is preferably 20 mN / m or more, and more preferably 25 mN / m or more.

[0094] The surface tension can be measured using an automatic surface tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.) by checking the surface tension when a platinum plate is wetted with the composition in an environment of 25°C.

[0095] The radiation-curable inkjet ink can be obtained by mixing the above-mentioned components in any order and removing impurities by filtration, etc., as necessary. A suitable method for mixing the components is to add the materials in order to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer and stir and mix them. As a filtration method, centrifugal filtration, filter filtration, etc. can be used as necessary.

[0096] The radiation-curable inkjet ink is cured by irradiating the coating with radiation. The cured coating is harder than, for example, a coating formed with a water-based ink, and therefore is prone to cracking when the first region on which the coating is formed shrinks together with the shrink film. However, since the shrink film of the present embodiment is provided with the above-mentioned second region, shrinkage of the first region is suppressed or prevented, and cracking can be suppressed.

[0097] 1.5. Effects, etc. In the shrink film of this embodiment, the second region shrinks preferentially over the first region when heated. This phenomenon is believed to be mainly due to the fact that the thicker the combined thickness of the shrink film and the coating of radiation curable ink, the easier it is to shrink. This phenomenon is also believed to be due in part to the fact that the hardness of the coating of radiation curable ink suppresses the shrinkage of the film.

[0098] Therefore, when the shrink film is shrunk by heating, the first region shrinks less than the second region, which makes it possible to suppress cracking of the coating of radiation-curable ink-jet ink formed in the first region. Furthermore, with this shrink film, the second region shrinks preferentially over the first region, so the first region shrinks less and distortion of the image of the coating formed in the first region due to shrinkage can be suppressed.

[0099] Fig. 2 is a schematic diagram showing the shrink film of this embodiment before and after shrinkage due to heat. The upper part of Fig. 2 shows the shrink film 100 before heating, and the lower part shows the shrink film 100 after heating. As shown in Fig. 2, in the shrink film 100 of this embodiment, as a result of the shrinkage of the second region 120, shrinkage of the image 114 formed in the first region 110 is suppressed, and therefore the shape of the image 114 hardly changes before and after shrinkage. This makes it unnecessary or simplified to edit the image 114 in the first region 110 to make it an image that takes the amount of shrinkage into account.

[0100] FIG. 3 is a schematic diagram showing a conventional shrink film before and after shrinkage due to heat. The upper part of FIG. 3 shows the conventional shrink film before heating, and the lower part shows the conventional shrink film after heating. In the conventional shrink film shown in FIG. 3, the image is deformed before and after shrinkage. Therefore, the conventional shrink film is prone to cracking of the coating. In addition, the conventional shrink film requires design editing to create an image that takes the amount of shrinkage into account.

[0101] 2. Container The container according to this embodiment is characterized in that the above-mentioned shrink film is heat-shrunk and placed on the outer periphery. The above-mentioned shrink film 100 can be cylindrical with a third side 103 and a fourth side 104 joined. When the container is placed inside the cylinder and heated, the second region 120 of the shrink film 100 shrinks in the first direction X and is placed on the outer periphery of the container.

[0102] In addition, a joint is formed in the shrink film 100 when the third side 103 and the fourth side 104 are joined. The joint can be formed by using an adhesive or by heat fusion, but such a joint does not belong to either the first or second region described above.

[0103] Examples of containers include bottles made of polymers such as polyethylene terephthalate (PET), polyethylene, and polypropylene, glass bottles, and metal cans. The containers can contain liquids and powders. The containers are preferably liquid containers that contain liquids. When the containers are liquid containers, the second region of the shrink film can be used as a liquid level visible portion that allows the liquid inside the container to be visually observed from the outside. In this way, the amount of liquid inside the container can be confirmed from the outside through the second region.

[0104] The container of this embodiment can be labeled with an image formed using the radiation curable inkjet ink described above, and therefore can be said to have a more robust label.

[0105] 3. Inkjet recording device The inkjet recording apparatus according to this embodiment includes a head that ejects a radiation curable inkjet ink, and a control unit that controls the head. The control unit performs a recording mode in which the radiation curable inkjet ink is applied to a film that contracts in a first direction when heated and has a rectangular shape in a plan view with a first side and a second side parallel to the first direction, and in the recording mode, the control unit forms a first region having an outline including a part of the first side and a part of the second side in a plan view and on which a coating of the radiation curable inkjet ink is formed, and a second region having a rectangular shape with two opposing sides defined by a part of the first side and a part of the second side and on which no coating of the radiation curable inkjet ink is formed or on which a coating of the radiation curable inkjet ink is formed that is thinner than that of the first region.

[0106] The inkjet recording apparatus of this embodiment includes a recording head that applies ultraviolet-curable ink to a shrink film, and an ultraviolet irradiating means that irradiates ultraviolet light to cure the applied coating film and form a cured film.

[0107] As an inkjet recording device for producing the shrink film according to this embodiment, for example, one shown in Fig. 4 can be used. Fig. 4 is a perspective view of an inkjet recording device that can be used in the shrink film recording method according to this embodiment. Fig. 5 is a front view of ultraviolet ray irradiation devices 90A (corresponding to 190A in Fig. 5) and 90B (corresponding to 190B in Fig. 5) shown in Fig. 4. Fig. 6 is a view taken along the arrow AA in Fig. 5.

[0108] The inkjet recording device 20 shown in Figure 4 comprises a motor 30 that feeds the shrink film P in the sub-scanning direction SS, a platen 40, a recording head 52 that sprays ultraviolet-curable ink in fine droplets from a head nozzle onto the shrink film P, a carriage 50 carrying the recording head 52, a carriage motor 60 that moves the carriage 50 in the main scanning direction MS, and a pair of ultraviolet irradiation devices 90A, 90B that irradiate ultraviolet rays onto the droplets of ultraviolet-curable ink ejected from the recording head 52 and deposited on the shrink film P.

[0109] The carriage 50 is pulled by a traction belt 62 driven by a carriage motor 60 and moves along a guide rail 64 .

[0110] The recording head 52 is mounted on a carriage 50, and moves in the main scanning direction MS (hereinafter also referred to as the "main scanning direction") as the carriage 50 moves in that direction.

[0111] The recording head 52 is also capable of ejecting ultraviolet-curable ink. In the example of Fig. 1, the recording head 52 is a serial type head for full-color printing that ejects four colors of ink, and each color is provided with a large number of head nozzles. In addition to the recording head 52, the carriage 50 on which the recording head 52 is mounted also mounts a black cartridge 54 as a black ink container that contains black ink to be supplied to the recording head 52, and a color ink cartridge 56 as a color ink that contains color ink to be supplied to the recording head 52. The ink contained in each cartridge 54, 56 is ultraviolet-curable ink, which is one form of the above-mentioned radiation-curable inkjet ink.

[0112] At the home position of the carriage 50 (the position on the right side in FIG. 4), a capping device 80 is provided for sealing the nozzle surface of the recording head 52 when the carriage 50 is stopped. When the print job ends and the carriage 50 reaches above this capping device 80, the capping device 80 automatically rises by a mechanism (not shown) to seal the nozzle surface of the recording head 52. This capping prevents the ink in the nozzles from drying out or deteriorating. The positioning control of the carriage 50 is performed, for example, to accurately position the carriage 50 at the position of this capping device 80.

[0113] By using such an inkjet recording device 20, it is possible to form a coating film by ejecting droplets of ultraviolet-curable ink onto the shrink film and attaching the ink to the shrink film. Furthermore, the inkjet recording device 20 makes it possible to continuously perform the coating film formation process and the curing process in one device, without performing the coating film formation process and the curing process in separate devices.

[0114] As an irradiation means capable of irradiating ultraviolet rays, for example, an ultraviolet ray irradiation device shown in FIG. 4 and FIG. 5 can be mentioned.

[0115] As shown in FIGS. 4 to 6, the ultraviolet ray irradiation devices 190A and 190B are attached to both ends of the carriage 50 along the moving direction thereof.

[0116] 5, the ultraviolet irradiation device 190A attached to the left side of the recording head 52 irradiates the droplets ejected onto the shrink film P with ultraviolet rays when the carriage 50 moves rightward (in the direction of arrow B in FIG. 5) in a right scan. Meanwhile, the ultraviolet irradiation device 190B attached to the right side of the recording head 52 irradiates the droplets ejected onto the shrink film P with ultraviolet rays when the carriage 50 moves leftward (in the direction of arrow C in FIG. 5) in a left scan.

[0117] Each of the ultraviolet irradiation devices 190A and 190B is attached to the carriage 50 and includes a housing 194 that supports one ultraviolet light source 192 in an aligned manner, and a light source control circuit (not shown) that controls the on / off of the ultraviolet light source 192. As shown in FIG. 5 and FIG. 6, each of the ultraviolet irradiation devices 190A and 190B is provided with one ultraviolet light source 192, but two or more may be provided. As the ultraviolet light source 192, it is preferable to use either an LED (Light Emitting Diode) or an LD (Laser Diode). This makes it possible to avoid the ultraviolet light source becoming larger due to the installation of a filter, etc., compared to the case where a mercury lamp, a metal halide lamp, or other lamps are used as the ultraviolet light source. In addition, the intensity of the emitted ultraviolet light does not decrease due to absorption by the filter, and the ultraviolet curable ink can be cured efficiently.

[0118] Furthermore, the ultraviolet light sources 192 may emit light having the same wavelength or different wavelengths. When an LED or an LD is used as the ultraviolet light source 192, the wavelength of the emitted ultraviolet light may be anywhere in the range of about 350.0 nm or more and 430.0 nm or less.

[0119] As shown in FIG. 4, with the ultraviolet irradiation devices 190A and 190B, droplets deposited on the shrink film P by ejection from the recording head 52 are irradiated with ultraviolet light 192a from an ultraviolet light source 192 that irradiates the shrink film P near the recording head 52, thereby hardening at least the surface of the droplets and forming an image on the shrink film.

[0120] The entire operation of the inkjet recording apparatus 20 is controlled by a control unit (not shown). The control unit performs a recording mode in which radiation curable inkjet ink is applied to the above-mentioned shrink film, and in this recording mode, the control unit forms, on the shrink film, a first region having an outline including a part of a first side and a part of a second side in a plan view and on which a coating of radiation curable inkjet ink is formed, and a second region having a rectangular shape with two opposing sides defined by a part of the first side and a part of the second side, where no coating of radiation curable inkjet ink is formed or where a coating of radiation curable inkjet ink that is thinner than that of the first region is formed.

[0121] According to the inkjet recording apparatus of this embodiment, it is possible to manufacture a shrink film in which the second region shrinks preferentially over the first region. Therefore, when the resulting shrink film is shrunk, cracks in the coating of the radiation curable inkjet ink formed in the first region can be suppressed. Furthermore, since the second region of the resulting shrink film shrinks preferentially over the first region, shrinkage in the first region is small, and distortion of the image due to shrinkage of the coating formed in the first region can be suppressed. This makes it possible to eliminate or simplify editing of the image in the first region to create an image that takes the amount of shrinkage into account.

[0122] The present invention includes configurations that are substantially the same as the configurations described in the embodiments, for example, configurations with the same functions, methods, and results, or configurations with the same purpose and effects. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that achieve the same effects as the configurations described in the embodiments, or configurations that can achieve the same purpose. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments.

[0123] The following can be derived from the above-described embodiment and modified examples.

[0124] Shrink film is A shrink film that shrinks in a first direction when heated, The shrink film has a rectangular shape in a plan view having a first side and a second side along the first direction, The shrink film, in plan view, a first region having an outline including a part of the first side and a part of the second side, on which a coating of a radiation curable inkjet ink is formed; a second region having a rectangular shape with two opposing sides defined by a part of the first side and a part of the second side, in which a coating film of the radiation curable ink-jet ink is not formed or a coating film of the radiation curable ink-jet ink that is thinner than that of the first region is formed; has.

[0125] With this shrink film, the second region shrinks preferentially over the first region. Therefore, when shrinking, cracking of the coating of radiation-curable inkjet ink formed in the first region can be suppressed. Furthermore, with this shrink film, the second region shrinks preferentially over the first region, so the shrinkage of the first region is small, and distortion of the image due to shrinkage of the coating formed in the first region can be suppressed. This makes it unnecessary or simplified to edit the image in the first region to create an image that takes the amount of shrinkage into account.

[0126] In the above shrink film, The length of the second region in the first direction may be greater than or equal to 1 / 20 and less than or equal to 1 / 5 of the length of the shrink film in the first direction.

[0127] This shrink film can prevent cracks in the coating of the radiation curable ink jet ink formed in the first region, and can also provide a sufficient amount of shrinkage.

[0128] In the above shrink film, In the first region, an image may be formed by a coating of the radiation curable inkjet ink.

[0129] This shrink film allows for labels with a more attractive design.

[0130] In the above shrink film, The coating of the radiation curable inkjet ink may contain a colorant.

[0131] This shrink film allows the formation of images with better color.

[0132] In the above shrink film, The radiation curable ink jet ink coating may be opaque.

[0133] This shrink film makes it easier to conceal the subject of the shrink film label.

[0134] In the above shrink film, The second region may not be coated with the radiation curable inkjet ink.

[0135] With this shrink film, the second region shrinks preferentially over the first region, further preventing cracks in the coating of the radiation curable inkjet ink formed in the first region.

[0136] In the above shrink film, The coating film of the radiation curable inkjet ink in the first region may have a thickness of 5 μm or more.

[0137] This shrink film makes it more difficult for the first region to shrink, and can further prevent cracks in the coating of the radiation curable inkjet ink formed in the first region.

[0138] In the above shrink film, The coating thickness of the radiation curable inkjet ink in the second region may be less than 5 μm.

[0139] This shrink film allows the second region to shrink more easily, further suppressing cracks in the coating of the radiation curable inkjet ink formed in the first region.

[0140] In the above shrink film, The shrink film may comprise polyethylene terephthalate.

[0141] This shrink film makes it easier to achieve a larger amount of shrinkage.

[0142] The container is characterized in that any one of the shrink films described above is heat-shrunk and placed on the outer periphery.

[0143] This container can be labeled with a radiation-curable ink-jet ink, resulting in a more durable label.

[0144] In the above container, It may be a container for liquids.

[0145] In the above container, The second region may be a liquid surface visible portion.

[0146] According to this container, the amount of liquid inside can be confirmed from the outside through the second region.

[0147] The inkjet recording device A head that ejects radiation curable inkjet ink; A control unit for controlling the head; having the control unit performs a recording mode in which the radiation curable inkjet ink is applied to a film that contracts in a first direction due to heating and has a rectangular shape in a plan view having a first side and a second side parallel to the first direction, In the recording mode, the control unit, in a plan view, a first region having an outline including a part of the first side and a part of the second side, on which a coating of a radiation curable inkjet ink is formed; a second region having a rectangular shape with two opposing sides defined by a part of the first side and a part of the second side, in which a coating film of the radiation curable ink-jet ink is not formed or a coating film of the radiation curable ink-jet ink that is thinner than that of the first region is formed; Form.

[0148] This inkjet recording device can produce a shrink film in which the second region shrinks preferentially over the first region. Therefore, when the resulting shrink film is shrunk, cracks in the coating of the radiation-curable inkjet ink formed in the first region can be suppressed. Furthermore, since the second region of the resulting shrink film shrinks preferentially over the first region, shrinkage in the first region is small, and distortion of the image due to shrinkage of the coating formed in the first region can be suppressed. This makes it unnecessary or simplified to edit the image in the first region to create an image that takes the amount of shrinkage into account. [Explanation of symbols]

[0149] 5...heater, 6...cooling fan, 20...inkjet recording device, 30...motor, 40...platen, 50...carriage, 52...recording head, 54...black ink cartridge, 56...color ink cartridge, 60...carriage motor, 62...traction belt, 64...guide rail, 80...capping device, 90A (190A), 90B (190B)...active radiation irradiation device, 101...first side, 102...second side, 103...third side, 104...fourth side, 110...first region, 120...second region, 112...coating film, 114...image, 192, 193...active radiation light source, 194...casing, P...shrink film, X...first direction

Claims

1. A shrink film that shrinks in a first direction when heated, The shrink film has a rectangular shape in a plan view having a first side and a second side along the first direction, The shrink film, in plan view, a first region having an outline including a part of the first side and a part of the second side, on which a coating of a radiation curable inkjet ink is formed; a second region having a rectangular shape with two opposing sides defined by a part of the first side and a part of the second side, in which a coating film of the radiation curable ink-jet ink is not formed or a coating film of the radiation curable ink-jet ink that is thinner than that of the first region is formed; A shrink film having

2. In claim 1, A shrink film, wherein the length of the second region in the first direction is greater than or equal to 1 / 20 and less than or equal to 1 / 5 of the length of the shrink film in the first direction.

3. In claim 1, A shrink film, wherein an image is formed in the first region by a coating of the radiation curable inkjet ink.

4. In claim 3, A shrink film, wherein the coating of the radiation curable inkjet ink contains a coloring material.

5. In claim 1, A shrink film, wherein the coating of the radiation curable inkjet ink is opaque.

6. In claim 1, The second region of the shrink film is not coated with the radiation curable inkjet ink.

7. In claim 1, a coating thickness of the radiation curable inkjet ink in the first region is 5 μm or more.

8. In claim 1, a coating thickness of the radiation curable inkjet ink in the second region is less than 5 μm.

9. In claim 1, The shrink film comprises polyethylene terephthalate.

10. A container comprising the shrink film according to any one of claims 1 to 9, which is heat-shrunk and disposed on an outer periphery of the container.

11. In claim 10, A container that is a container for liquids.

12. In claim 11, The second region is a portion where the liquid level is visible.

13. A head that ejects radiation curable inkjet ink; A control unit for controlling the head; having the control unit performs a recording mode in which the radiation curable inkjet ink is applied to a film that contracts in a first direction due to heating and has a rectangular shape in a plan view having a first side and a second side parallel to the first direction, In the recording mode, the control unit, in a plan view, a first region having an outline including a part of the first side and a part of the second side, on which a coating of a radiation curable inkjet ink is formed; a second region having a rectangular shape with two opposing sides defined by a part of the first side and a part of the second side, in which a coating film of the radiation curable ink-jet ink is not formed or a coating film of the radiation curable ink-jet ink that is thinner than that of the first region is formed; An inkjet recording apparatus.

Images