JP6966932B2 - Ink pouches and ink packs - Google Patents

Description

The present invention relates to an ink pouch. The present invention also relates to an ink pack in which a solvent-based inkjet ink is contained in an ink pouch.

An inkjet recording device that employs an inkjet recording method has advantages such as easy operation, low noise, and easy color printing, and is therefore used not only for home use and office use but also for industrial use.

In an inkjet recording device, ink is stored in an ink container. For example, in a large inkjet recording device used for industrial applications, it is often configured that an ink pack containing ink in a bag-shaped container (that is, an ink pouch) formed of a multilayer film is stored in an ink cartridge. It has been adopted.

Polyethylene is known as a material constituting an ink pouch (see, for example, Patent Document 1). Specifically, for example, Patent Document 1 discloses that an ink pouch in which a multilayer film having an innermost layer made of polyethylene in the form of a bag is used for an ink pack.

Japanese Unexamined Patent Publication No. 2009-83133

However, as a result of diligent studies by the present inventor, when an ink pouch having an innermost layer containing polyethylene is used for accommodating a solvent-based inkjet ink, the polyethylene in the innermost layer may elute into the solvent-based inkjet ink. I found. If polyethylene eluted in the solvent-based inkjet ink precipitates, it may cause problems such as clogging of the inkjet head and clogging of the ink path when forming an image using an inkjet recording device.

The present invention has been made in view of this point, and an object thereof is to provide an ink pouch having an innermost layer containing polyethylene and in which elution of the polyethylene into a solvent-based inkjet ink is suppressed. To do.

The ink pouch of the present invention includes an innermost layer containing polyethylene. The crystallinity of the polyethylene is 39% or more and 51% or less, and the melting point of the polyethylene is 120 ° C. or more and 129 ° C. or less.

The ink pack of the present invention includes the ink pouch and the solvent-based inkjet ink contained in the ink pouch.

According to the present invention, there is provided an ink pouch in which elution of polyethylene constituting the innermost layer into a solvent-based inkjet ink is suppressed.

It is a top view of one Embodiment of the ink pouch of this invention. FIG. 2 is a cross-sectional view taken along the line II-II of FIG.

The ink pouch according to the present invention includes an innermost layer containing polyethylene. The crystallinity of the polyethylene is 39% or more and 51% or less, and the melting point of the polyethylene is 120 ° C. or more and 129 ° C. or less.

The ink pouch according to the present invention usually has a multilayer structure composed of a multilayer film. The ink pouch according to the present invention is usually a bag-shaped container in which the end portion of the multilayer film is heat-welded. The innermost layer of the multilayer structure is a layer that comes into contact with the ink when the ink is contained, and contains polyethylene. Further, this innermost layer functions as a sealant layer, and therefore, the innermost layers are heat-welded to each other at the end portion of the multilayer film.

As used herein, the term "polyethylene" refers to a homopolymer of ethylene, a copolymer of ethylene and an α-olephyllene monomer of 5 mol% or less, and ethylene and a functional group containing only carbon, oxygen, and hydrogen atoms. It means a copolymer with 1 mol% or less of a non-olefin monomer.

Even if polyethylene has the same composition, its properties differ greatly depending on its structure. Therefore, polyethylene is classified into many categories such as high density polyethylene (HDPE), low density polyethylene (LDPE), ultra low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), and ultra high molecular weight polyethylene (UHMW-PE). It is a special polymer having. The present inventor has studied various physical characteristics of polyethylene in order to suppress the elution of polyethylene into solvent-based inkjet inks. As a result, it has been found that an ink pouch using polyethylene having a specific crystallinity and a specific melting point as the innermost layer can suppress elution of the polyethylene into a solvent-based inkjet ink.

If the crystallinity of the polyethylene constituting the innermost layer is too small, the polyethylene elutes in the solvent-based inkjet ink. Therefore, in the present invention, the crystallinity of polyethylene constituting the innermost layer is 39% or more, preferably 40% or more. On the other hand, if the crystallinity of the polyethylene constituting the innermost layer is too high, the multilayer film becomes too hard and the pouch becomes difficult to deform, and the function as a pouch is impaired, for example, the remaining amount of ink cannot be grasped. Therefore, in the present invention, the crystallinity of polyethylene constituting the innermost layer is 51% or less, preferably 50% or less. The crystallinity of polyethylene can be determined by X-ray diffraction (XRD) measurement.

Further, if the melting point of the polyethylene constituting the innermost layer is too low, the polyethylene elutes in the solvent-based inkjet ink. Therefore, in the present invention, the melting point of polyethylene constituting the innermost layer is 120 ° C. or higher, preferably 121 ° C. or higher, and more preferably 122 ° C. or higher. On the other hand, if the melting point of the polyethylene constituting the innermost layer is too high, the multilayer film becomes too hard and the pouch becomes difficult to deform, and the remaining amount of ink cannot be grasped, and the function as a pouch is impaired. Therefore, in the present invention, the melting point of polyethylene constituting the innermost layer is 129 ° C. or lower, preferably 128 ° C. or lower. The melting point of polyethylene can be determined by differential scanning calorimetry (DSC) measurement.

Methods for producing polyethylene with different crystallinities and different melting points are known. In the ink pouch according to the present invention, the polyethylene constituting the innermost layer is preferably linear low density polyethylene (LLDPE).

The structure of the multilayer film is not particularly limited as long as the innermost layer contains polyethylene having a crystallinity and a melting point within the above range. The material constituting the layer other than the innermost layer of the multilayer film may be appropriately determined according to the desired characteristics of the multilayer film. The multilayer film may have a layer containing polyethylene in addition to the innermost layer. The physical characteristics of the polyethylene contained in the layers other than the innermost layer are not particularly limited, and may be appropriately selected depending on the desired characteristics of the multilayer film. The multilayer film may have an adhesive layer for adhering the layers.

The number of layers of the multilayer film is not particularly limited, and may be appropriately determined according to the desired characteristics of the multilayer film. The number of layers of the multilayer film is, for example, 2 to 7 layers, preferably 3 layers or 4 layers.

As an example of the layer structure of the three-layer multilayer film, when the layer structure is described in the order of outermost layer / intermediate layer / innermost layer, polyethylene terephthalate layer / polyvinyl alcohol / ethylene copolymer layer / polyethylene layer, stretched polypropylene layer. / Polyvinyl alcohol / ethylene copolymer layer / polyethylene layer, unstretched polypropylene layer / polyvinyl alcohol / ethylene copolymer layer / polyethylene layer, nylon layer / aluminum layer / polyethylene layer, polyethylene terephthalate layer / aluminum layer / polyethylene layer, aluminum Examples thereof include a layer / paper layer / polyethylene layer, a paper layer / aluminum layer / polyethylene layer, a polyethylene layer / a polyvinyl chloride-coated nylon layer / polyethylene layer, a stretched polypropylene layer / a polyvinylidene chloride-coated nylon layer / a polyethylene layer, and the like.

As an example of the layer structure of the four-layer multilayer film, when the layer structure is described in the order of outermost layer / first intermediate layer / second intermediate layer / innermost layer, cellophane layer / polyethylene layer / aluminum layer / polyethylene layer, Polyethylene terephthalate layer / polyethylene layer / aluminum layer / polyethylene layer, nylon layer / polyethylene layer / aluminum layer / polyethylene layer, paper layer / polyethylene layer / aluminum foil layer / polyethylene layer, polyethylene terephthalate layer / aluminum layer / polyethylene terephthalate layer / polyethylene Examples thereof include a layer, a polyethylene terephthalate layer / an aluminum layer / a polyethylene layer / a polyethylene layer and the like.

In addition to the above-mentioned materials, each layer of the multilayer film may contain other components such as additive components.

In the ink pouch according to the present invention, the elution of polyethylene constituting the innermost layer into the solvent-based inkjet ink is suppressed. Therefore, the ink pouch according to the present invention can be suitably used for a container for solvent-based inkjet ink. Further, the ink pouch according to the present invention can also be used as a container for inks other than solvent-based inkjet inks (for example, inkjet inks such as water-based inkjet inks and active energy ray-curable inkjet inks).

In the present specification, the "solvent-based inkjet ink" refers to an inkjet ink containing an organic solvent as a main component and not containing water as a component for exhibiting the function and performance of the ink. .. The content of water in the solvent-based inkjet ink is preferably 5% by mass or less, more preferably 1% by mass or less, and further preferably 0% by mass.

When the ink pouch according to the present invention contains a solvent-based inkjet ink, it is preferable to include an aluminum layer as an intermediate layer and a polyethylene terephthalate layer as an outermost layer. In the present specification, the "intermediate layer" means a layer existing between the outermost layer and the innermost layer. On the other hand, when the ink pouch according to the present invention accommodates an active energy ray-curable inkjet ink, it is preferable that the ink pouch does not have an aluminum layer having a high gas barrier property from the viewpoint of storage stability.

From another aspect, the present invention is an ink pack including the ink pouch (that is, the ink pouch described as the ink pouch according to the present invention) and the solvent-based inkjet ink contained in the ink pouch.

Hereinafter, preferred examples of the solvent-based inkjet ink contained in the ink pouch will be described, but the solvent-based inkjet ink contained in the ink pouch is not limited thereto. A suitable solvent-based inkjet ink contains an organic solvent, a binder resin, and a coloring material.

The organic solvent is preferably contained in the solvent-based inkjet ink in an amount of 70% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass or more. As the organic solvent, one type of solvent used in known solvent-based inkjet inks can be used alone, or two or more types can be used in combination. The organic solvent preferably contains a solvent represented by the following formula (1) (hereinafter, also referred to as “solvent (1)”) and an aprotic polar solvent.
R ¹ O- (R ² O) _n- R ³ ... (1)
(In the formula, R ¹ is a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, R ² is an alkylene group having 2 or 3 carbon atoms, and R ³ is a hydrogen atom. , An acetyl group, or a linear or branched alkyl group having 1 to 4 carbon ^{atoms, where both R 1} and R ³ are not hydrogen atoms. N is an integer of 1 to 7. )

In the above formula (1), R ¹ is preferably a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. R ³ is preferably a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. n is preferably 2 or 3.

Examples of the solvent (1) include diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, triethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, and triethylene glycol. Monobutyl Ether, Diethylene Glycol Monoisobutyl Ether, Triethylene Glycol Monoisobutyl Ether, Dipropylene Glycol Monomethyl Ether, Tripropylene Glycol Monomethyl Ether, Dipropylene Glycol Monoethyl Ether, Tripropylene Glycol Monoethyl Ether, Dipropylene Glycol Monopropyl Ether, Tripropylene Glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, diethylene glycol diisopropyl ether, triethylene glycol diisopropyl ether, diethylene glycol dibutyl ether, tri Examples thereof include ethylene glycol dibutyl ether, dipropylene glycol dimethyl ether, tripropylene glycol dimethyl ether, dipropylene glycol diethyl ether, and tripropylene glycol diethyl ether. The content of the solvent (1) in the solvent-based inkjet ink is preferably 40% by mass or more and 95% by mass or less.

Examples of the aprotic polar solvent include pyrrolidone and its derivatives, lactone compounds, 1,3-dimethyl-2-imidazolidinone and the like. Of these, lactone compounds are preferred. Examples of lactone compounds include α-ethyl lactone, α-acet lactone, β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, ζ-enantiiolactone, η-caprylolactone, γ-valero. Examples thereof include lactone, γ-heptalactone, γ-nonalactone, β-methyl-δ-valerolactone, 2-butyl-2-ethylpropiolactone, α, α-diethylpropiolactone and the like. Of these, γ-butyrolactone is preferable. The content of the aprotic polar solvent in the solvent-based inkjet ink is preferably 3% by mass or more and 30% by mass or less.

In a preferred example of the organic solvent, the organic solvent contains a solvent represented by the following formula (2) (hereinafter, also referred to as “solvent (2)”) as the solvent (1), and is used as an aprotic polar solvent. Contains a lactone compound. In the preferred example, the organic solvent may further contain a solvent represented by the following formula (3) (hereinafter, also referred to as “solvent (3)”) as the solvent (1).
R ⁴ O- (R ⁵ O) _m- R ⁶ ... (2)
(In the formula, R ⁴ is a linear or branched alkyl group having 1 to 6 carbon atoms, R ⁵ is an alkylene group having 2 or 3 carbon atoms, and R ⁶ is an alkylene group having 1 to 4 carbon atoms. It is a linear or branched alkyl group, and m is an integer of 1 to 7.)
R ⁷ O- (R ⁸ O) _k- H ... (3)
(In the formula, R ⁷ is a linear or branched alkyl group having 1 to 6 carbon atoms, R ⁸ is an alkylene group having 2 or 3 carbon atoms, and k is an integer of 1 to 7. )

In the above formula (2), R ⁴ is preferably a linear or branched alkyl group having 1 to 4 carbon atoms. m is preferably 2 or 3. In the above formula (3), R ⁷ is preferably a linear or branched alkyl group having 1 to 4 carbon atoms. k is preferably 2 or 3.

In the preferred example, the content ratio of the solvent (2) with respect to the total mass of the solvent-based inkjet ink is preferably 40% by mass or more and 95% by mass or less. The content ratio of the solvent (3) with respect to the total mass of the solvent-based inkjet ink is preferably 0% by mass or more and 50% by mass or less. The content ratio of the lactone compound to the total mass of the solvent-based inkjet ink is preferably 5% by mass or more and 20% by mass or less.

The binder resin is a component for fixing the coloring material to the media. Examples of binder resins include acrylic resins, styrene acrylic resins, rosin-modified resins, phenol resins, terpene resins, polyester resins, polyamide resins, epoxy resins, vinyl acetate resins, vinyl chloride resins, cellulose acetate butyrate and other fiber-based resins. Examples thereof include resins, vinyl toluene-α-methylstyrene copolymer resins and the like. The content of the binder resin in the solvent-based inkjet ink is preferably 0.5% by mass or more and 15% by mass or less.

The coloring material is a coloring component. Examples of the coloring material include dyes, pigments and the like, which may be known. The content of the coloring material in the solvent-based inkjet ink is preferably 0.5% by mass or more and 25% by mass or less.

Solvent-based inkjet inks include polymer dispersants, surfactants, plasticizers, antistatic agents, viscosity modifiers, surface tension regulators, leveling agents, defoamers, antioxidants, pH regulators, UV absorbers, etc. It may contain various additives such as a light stabilizer, an antistatic agent, and a killing agent.

Hereinafter, a specific embodiment of the ink pouch according to the present invention will be described with reference to the drawings as an example, but the present invention is not limited to the embodiment. FIG. 1 is a plan view of the ink pouch 100 according to the present embodiment. FIG. 2 is a cross-sectional view taken along the line II-II of FIG.

As shown in FIG. 1, the ink pouch 100 includes a bag-shaped portion 10 for accommodating ink. As shown in FIG. 2, the bag-shaped portion 10 is composed of two multilayer films 40. At the end of the bag-shaped portion 10, a welded portion 12 in which two multilayer films 40 are heat-welded is formed. An internal space 50 surrounded by two multilayer films 40 is formed in the bag-shaped portion 10. The solvent-based inkjet ink is housed in the internal space 50. Since the multilayer film 40 has flexibility, the volume of the internal space 50 can be changed. Therefore, the bag-shaped portion 10 may expand or contract depending on the amount of the solvent-based inkjet ink in the ink pouch 100.

In the present embodiment, as shown in FIG. 2, the multilayer film 40 has a three-layer structure composed of an innermost layer 42, an intermediate layer 44, and an outermost layer 46. The innermost layer 42 is a polyethylene layer. The polyethylene contained in the innermost layer 42 has a crystallinity in the range of 39% or more and 51% or less (for example, 45%) and a melting point in the range of 120 ° C. or more and 129 ° C. or less (for example, 123 ° C.). There is. The innermost layer 42 has the role of a sealant layer welded by heat welding. The innermost layer 42 comes into contact with the solvent-based inkjet ink contained in the internal space 50.

In this embodiment, the intermediate layer 44 is an aluminum layer. Since the aluminum layer has low moisture permeability and low air permeability, the intermediate layer 44 serves as a gas barrier layer. In this embodiment, the outermost layer 46 is a polyester layer (for example, a polyethylene terephthalate layer). The outermost layer 46 has a role as a protective layer of the intermediate layer 44. Further, although not shown, an adhesive layer for adhering the layers is formed between the innermost layer 42 and the intermediate layer 44, and between the outermost layer 46 and the intermediate layer 44.

As shown in FIG. 1, the ink pouch 100 has a ejection unit 20 for ejecting solvent-based inkjet ink contained in the internal space 50 of the bag-shaped portion 10. The discharge portion 20 is provided at the end of the bag-shaped portion 10. The ejection unit 20 has a through hole (not shown) through which the solvent-based inkjet ink can pass. A cap 30 is attached to the tip of the discharge portion 20, and the through hole is sealed by the cap 30.

The ink pouch according to the present invention can be produced according to a conventional method. The ink pouch according to the present invention can be used as a pouch-type ink container according to a conventional method. The ink pack containing the solvent-based inkjet ink in the ink pouch according to the present invention can be used according to a conventional method. For example, it can be used by accommodating the ink pack in an ink cartridge and mounting the ink cartridge in an inkjet recording device. According to the ink pouch according to the present invention, the elution of polyethylene constituting the innermost layer into the contained solvent-based inkjet ink is suppressed. Therefore, when the image is formed by the inkjet recording apparatus, problems such as clogging of the inkjet head and clogging of the ink path are solved, and stable image formation can be performed.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

[Preparation of Ink Pouches of Examples and Comparative Examples]
Using a multilayer film having a polyethylene layer, an aluminum layer, and a polyethylene terephthalate layer, ink pouches of each example and each comparative example of the embodiment shown in FIG. 1 were prepared by a heat welding method. At this time, the polyethylene layer was arranged in the innermost layer, and the polyethylene terephthalate layer was arranged in the outermost layer. As the innermost polyethylene layer, one having the crystallinity and melting point shown in Table 1 was used. The crystallinity of the polyethylene constituting the innermost layer was determined by XRD measurement. The melting point of polyethylene constituting the innermost layer was determined by DSC measurement.

[Evaluation of polyethylene elution]
As the evaluation ink, a solvent-based inkjet ink containing 78.5% by mass of diethylene glycol diethyl ether, 10% by mass of γ-butyrolactone, 3.5% by mass of pigment, and 8% by mass of binder resin was prepared. This evaluation ink was housed in each of the prepared ink pouches and stored at 60 ° C. for 1 week. Furthermore, it was stored at room temperature for 1 day. Then, 10 mL of the evaluation ink was extracted from the ink pouch and filtered by its own weight with a 3000 mesh stainless steel filter (opening 5 μm). At this time, the time required for all the ink to pass through the filter (filtration time) was measured. If polyethylene elutes when stored at 60 ° C., polyethylene precipitates when stored at room temperature. When polyethylene is deposited, the filtration time becomes long, so the filtration time is an index of the elution of polyethylene. Therefore, those having a filtration time of less than a predetermined time were designated as "○ (good)", and those having a filtration time exceeding a predetermined time were designated as "x (poor)". The results are shown in Table 1.

[Evaluation of pouch deformability]
The evaluation ink used for the evaluation of the elution of polyethylene was housed in each of the ink pouches prepared above. The ink pouch was placed on a tray slightly tilted from the horizontal and fitted with an empty sensor, suction pump, and pressure gauge. A laser displacement meter was installed above the tray and ink pouch. Ink was ejected from the ink pouch using a suction pump. The ink sucked by the suction pump was transferred to the bottle, and the weight of the ink discharged from the ink pouch was confirmed. While the ink was ejected, the height of the upper surface of the ink pouch was measured with a laser displacement meter. As the ink is discharged, the ink pouch is deformed (shrinked), and the position of the upper surface of the ink pouch becomes lower. When the remaining amount of ink is 50 mL or less, the height of the upper surface of the ink pouch is "○ (good)", and the height of the upper surface of the ink pouch exceeds the specified value. × (defective) ”. The results are shown in Table 1.

From the results in Table 1, when the crystallinity of polyethylene constituting the innermost layer of the ink pouch is 39% or more and 51% or less and the melting point is 120 ° C. or more and 129 ° C. or less, the solvent-based inkjet ink contained is contained. It can be seen that the elution of polyethylene into the ink pouch is suppressed and that the ink pouch has sufficient deformability. On the other hand, apart from the above, the molecular weight of polyethylene constituting the innermost layer of the ink pouch, the glass transition temperature, etc. were examined, but these physical characteristics parameters are sufficiently correlated with the elution of polyethylene and the deformability of the pouch. Was not seen. Therefore, according to the present invention, it can be seen that an ink pouch having an innermost layer containing polyethylene and in which elution of the polyethylene into a solvent-based inkjet ink is suppressed can be provided.

The ink pouch according to the present invention is useful as a container for ink (particularly solvent-based inkjet ink).

10 Bag-shaped part 12 Welding part 20 Discharge part 30 Cap 40 Multilayer film 42 Inner layer 44 Intermediate layer 46 Outer layer 50 Inner space 100 Ink pouch

Claims (8)

An ink pouch with an innermost layer containing polyethylene.
The crystallinity of the polyethylene is 39% or more and 51% or less, and the melting point of the polyethylene is 120 ° C. or more and 129 ° C. or less.
An ink pouch featuring that. The ink pouch according to claim 1, wherein the polyethylene has a crystallinity of 40% or more and 50% or less, and the polyethylene has a melting point of 120 ° C. or more and 128 ° C. or less. The ink pouch according to claim 1 or 2, which is used for solvent-based inkjet ink. The ink pouch according to claim 3, further comprising an aluminum layer as an intermediate layer and a polyethylene terephthalate layer as an outermost layer. The ink pouch according to any one of claims 1 to 4, and a solvent-based inkjet ink contained in the ink pouch.
Ink pack. The solvent-based inkjet ink contains an organic solvent, a binder resin, and a coloring material.
The ink pack according to claim 5, wherein the organic solvent contains a solvent represented by the following formula (1) and an aprotic polar solvent.
R ¹ O- (R ² O) _n- R ³ ... (1)
(In the formula, R ¹ is a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, R ² is an alkylene group having 2 or 3 carbon atoms, and R ³ is a hydrogen atom. , An acetyl group, or a linear or branched alkyl group having 1 to 4 carbon ^{atoms, where both R 1} and R ³ are not hydrogen atoms, and n is an integer of 1 to 7. ) The ink pack according to claim 6, wherein the aprotic polar solvent is a lactone compound. The organic solvent is 40% by mass or more and 95% by mass or less of the solvent represented by the following formula (2) as the solvent represented by the formula (1) with respect to the total mass of the solvent-based inkjet ink. The solvent represented by 1) contains 0% by mass or more and 50% by mass or less of the solvent represented by the following formula (3), and the aprotonic polar solvent contains 5% by mass or more and 20% by mass or less of the lactone compound. The ink pack according to claim 6 or 7.
R ⁴ O- (R ⁵ O) _m- R ⁶ ... (2)
(In the formula, R ⁴ is a linear or branched alkyl group having 1 to 6 carbon atoms, R ⁵ is an alkylene group having 2 or 3 carbon atoms, and R ⁶ is an alkylene group having 1 to 4 carbon atoms. It is a linear or branched alkyl group, and m is an integer of 1 to 7.)
R ⁷ O- (R ⁸ O) _k- H ... (3)
(In the formula, R ⁷ is a linear or branched alkyl group having 1 to 6 carbon atoms, R ⁸ is an alkylene group having 2 or 3 carbon atoms, and k is an integer of 1 to 7. )

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