JP2009051543A - Packaging material with UV protection - Google Patents

Abstract

The present invention relates to a packaging material having UV-cutting properties, which can be printed on a base sheet mainly composed of paper using a normal printing ink, and has light resistance so that the ink does not fade or discolor due to light. Is intended to provide.
A packaging material comprising a base sheet mainly composed of paper, the base sheet (1), a printing ink layer (2) on the outer surface of the base sheet (1), and the printing ink And an overprint varnish layer (3) provided so as to cover the printing surface including the layer (2), wherein the overprint varnish layer (3) comprises at least a hydroxyphenyltriazine compound. It is the packaging material which has the ultraviolet cut property characterized by being comprised from the overprint varnish composition containing this.
[Selection] Figure 1

Description

  The present invention relates to a packaging material having an ultraviolet ray-cutting property, and more specifically, it is possible to print on a base sheet mainly composed of paper using a normal printing ink, and the light resistance that the ink does not fade or discolor due to light. It is related with the packaging material which has UV cut property provided.

  Conventionally, a packaging material composed of a base sheet mainly composed of paper used for packaging foods, non-foods, etc., generally has a printing ink layer on the outer surface of the base sheet (1) as shown in FIG. (2) and an overprint varnish layer (3) provided so as to cover the printing surface including the printing ink layer (2). Such packaging materials are required to have various functions. For example, improvement of gloss on the printed surface, water repellency, light resistance, heat resistance, wear resistance and the like can be mentioned. As countermeasures against these problems, a normal overprint varnish (usually OP varnish) in which polyethylene wax or a silicone-based additive is added to the overprint varnish layer (3), and recently, an ultraviolet curable (UV) overprint varnish ( UVOP varnish) and UV curable (UV) high gloss varnish (UV high gloss varnish) are used, but satisfactory results are not always obtained.

  Therefore, especially for the light fastness measures that the printing ink printed on the outer surface of the base sheet does not fade or discolor due to light, the pigment constituting the printing ink is not a regular pigment but a special light fastness. It uses printing ink made by changing to a strong light-resistant pigment. However, this light-resistant pigment has disadvantages that the printing workability is not good because the unit price is high, the printability is poor, and the switching time for color change is increased.

  Then, as shown in FIG. 5, the proposal which makes the overprint varnish composition used for the said overprint varnish layer (3) contain a benzotriazole (BTZ) type ultraviolet absorber is made | formed (for example, patent document). 1).

  However, in this case, as shown in FIG. 6, a benzotriazole (BTZ) -based ultraviolet absorber, for example, a product name “TINUVIN PS” manufactured by Ciba Specialty Chemicals Co., Ltd., is dissolved in toluene at various addition rates. As can be seen from the absorption characteristics of each wavelength of ultraviolet rays, when the addition amount of the ultraviolet absorber is small, the transmittance value is large and sufficient light resistance cannot be obtained. Therefore, when the added amount is increased, problems such as poor adhesion due to bleeding occur. That is, when an ultraviolet absorber is simply added to a normal coating solution (for example, normal OP varnish, UVOP varnish, UV high gloss varnish), a sufficient amount of the ultraviolet absorber cannot be applied to the packaging material. It was. In other words, if a large amount of UV absorber is added, the coating suitability of the coating liquid will be reduced. Even if a large amount of UV absorber is added forcibly, the UV absorber will bleed out and fall off. There was a problem of doing.

  Therefore, if the coating liquid added with an appropriate amount is coated twice, for example, to increase the thickness of the coating film, the UV-cutting performance will be improved, but the coating film will become harder and cracks will easily occur. There was a problem that flexibility decreased and suitability as a packaging material was impaired.

  Furthermore, the benzotriazole (BTZ) -based UV absorber is greatly deteriorated with time, and cannot maintain light resistance for a long time.

Prior art documents are shown below.
JP 11-277924 A

  The present invention is intended to solve such problems of the prior art, and can be printed on a base sheet mainly composed of paper using a normal printing ink, and the ink is faded by light, An object of the present invention is to provide a packaging material having an ultraviolet cut property having light resistance that does not change color.

  The present invention has been made to solve the above problems, and the invention according to claim 1 of the present invention is a packaging material comprising a base sheet mainly composed of paper, the base sheet (1) and an overprint varnish layer (3) provided by coating the outer surface of the substrate sheet (1) with a printing ink layer (2) and a printing surface including the printing ink layer (2) And the overprint varnish layer (3) is composed of an overprint varnish composition containing at least an ultraviolet absorber (4) made of a hydroxyphenyltriazine-based compound. Material.

  The invention according to claim 2 of the present invention is the packaging material having ultraviolet cut-off property according to claim 1, wherein the ultraviolet absorber (4) is 0.1 based on the solid content of the overprint varnish composition. It is contained in the ratio of 10 to 10 weight%, The packaging material which has the ultraviolet cut property of Claim 1 or 2 characterized by the above-mentioned.

  The packaging material having ultraviolet cut-off properties according to the present invention is a packaging material comprising a base sheet mainly composed of paper, the base sheet, a printing ink layer on the outer surface of the base sheet, and the printing ink An overprint varnish layer provided to cover a printing surface including a layer, and the overprint varnish layer is composed of an overprint varnish composition containing an ultraviolet absorber composed of at least a hydroxyphenyltriazine compound. As a result, deterioration with time is reduced and light resistance can be maintained for a long time, so printing with ordinary printing ink becomes possible and contributes to improvement in printing quality. In addition, the switching time for color change is reduced and the printing workability is improved, so the printing unit price is reduced.

  An embodiment of the present invention will be described in detail with reference to FIGS.

  FIG. 1 is a side sectional view showing one embodiment of a layer structure of a packaging material having ultraviolet cut-off properties according to the present invention, and FIG. 2 is a hydroxyphenyl triazine compound used for the packaging material having ultraviolet cut-off properties according to the present invention. FIG. 3 is a view showing one example of a chemical structural formula of an ultraviolet absorber made of (HPT), and FIG. 3 shows an ultraviolet absorption made of a hydroxyphenyltriazine compound (HPT) used for a packaging material having ultraviolet cut-off properties according to the present invention. It is a graph which shows the absorption characteristic of an agent.

  As shown in FIG. 1, the layer structure of a packaging material having ultraviolet cut-off properties according to one embodiment of the present invention is a packaging material composed of a base sheet mainly composed of paper, and the base sheet (1 A printing ink layer (2) on the outer surface of the substrate sheet (1), and an overprint varnish layer (3) provided so as to cover the printing surface including the printing ink layer (2), The overprint varnish layer (3) is a packaging material having an ultraviolet-cutting property composed of an overprint varnish composition containing an ultraviolet absorber (4) comprising at least a hydroxyphenyltriazine compound.

  As the base sheet (1), a base sheet (1) mainly composed of paper can be arbitrarily used. Examples of the paper mainly composed of pulp include coated balls, manila balls, pure white roll paper, Fine paper, kraft paper, coated paper, art paper, sulfate paper, glassine paper, parchment paper, paraffin paper, Japanese paper and the like can be used. In addition to the base material sheet (1) using only paper as described above, a resin processed paper obtained by extrusion lamination of polyethylene resin, polypropylene resin, vinyl chloride resin, or the like, or a film made of the resin was laminated to these paper base materials. Film processed paper or the like can also be used.

The thickness of the base sheet (1) is not particularly limited. However, when considering the suitability as a packaging material, the printability of the base sheet (1) and the overprint varnish workability, the basis weight is 20 to 500 g / A range of about m ² is preferable.

  Next, a known printing technique can be used as a method of providing the printing ink layer (2). For example, there are an offset printing method, a gravure printing method, a silk screen printing method, a flexographic printing method, a relief printing method, and the like. Among these, an offset printing method and a gravure printing method are preferably used. The number of colors is not limited to one color, and may be a multi-layered printing ink layer (2) printed with multicolor printing inks.

  The offset printing ink used in the offset printing method includes oil-based ink and ultraviolet curable ink, and the composition of the oil-based ink is a vehicle and an auxiliary agent in which a colorant composed of a pigment or a dye and a synthetic resin are dissolved in a solvent ( A drying adjusting agent, a film adjusting agent, etc.). As the vehicle, a dry oil type (for example, rosin modified phenolic resin, linseed oil and high boiling petroleum solvent) is used.

  The composition of the UV curable ink is pigment, oligomer (prepolymer, photopolymerizable low polymer), monomer (reactive diluent, photopolymerizable monomer), photopolymerization initiator (sensitizer), additive. Etc.

  The composition of the gravure printing ink used in the gravure printing method is a vehicle and an auxiliary agent (stabilizer, slip) in which a binder resin (fixing agent) made of a colorant made of pigment or dye and a synthetic resin is dissolved in a solvent. Agent).

  As the binder resin (fixing agent), a resin that can be dissolved or dispersed in a solvent is used. For example, resins such as vinyl chloride, chlorinated polypropylene, vinyl chloride-vinyl acetate copolymer, nitrocellulose, urethane, polyester, and polyamide are used.

  Next, the overprint varnish layer (3) provided so as to cover the printing surface including the printing ink layer (2) contains at least an ultraviolet absorber (4) made of a hydroxyphenyltriazine compound. It is composed of things.

  In general, for UV absorbers, benzophenone and benzotriazole have been widely used due to the current cost, UV absorption range, variety, and application range. In addition, due to the decrease in absorbing species, fading and resin deterioration over time were inevitable.

  Therefore, in order to achieve high light resistance, it was necessary to add so as to have a high concentration. However, on the other hand, it may cause a restriction such as poor adhesion due to bleeding or the like, and depending on the resin, it cannot be added at high concentration.

  Therefore, in the triazine system of the present invention, if there is no problem in compatibility with the resin, the molecular weight is larger than that of the conventional system, the triazine skeleton suppresses bleed, and there is less bleed and volatilization than in the past. Therefore, it is possible to maintain the ultraviolet absorbing ability over a long period of time.

  As shown in FIG. 2, a hydroxyphenyl triazine (HPT) -based compound, for example, an ultraviolet absorber (4) manufactured by Ciba Specialty Chemicals Co., Ltd. and trade name “TINUVIN 479” is preferable.

  FIG. 3 shows an ultraviolet absorber of the hydroxyphenyl triazine (HPT) -based compound (manufactured by Ciba Specialty Chemicals Co., Ltd., trade name “TINUVIN 479”) dissolved in toluene at various addition rates. It is a figure showing the absorption characteristic.

  Thus, the overprint varnish composition containing the ultraviolet absorber (4) made of a hydroxyphenyltriazine compound is a conventional benzotriazole (BTZ) ultraviolet absorber, for example, Ciba Specialty, as shown in FIG. Compared to the UV absorption characteristics of the chemical name “TINUVIN PS” manufactured by Chemicals Co., Ltd., a remarkable difference is seen, and even if the addition amount is small, the transmittance value is small and sufficient light resistance can be obtained. .

  By the way, the overprint varnish composition for forming the overprint varnish layer (3) in the present invention is an overprint varnish composition (usually OP varnish, UVOP varnish, UV high gloss varnish) is applied.

  When the normal OP varnish composition is applied by an offset printing method, except for an ultraviolet absorber, a rosin-modified phenolic resin, a rosin-modified maleic resin, a fiber-based resin, an alkyd resin, or a dry oil-modified resin thereof. 20-80% by weight of a resin, 0-80% by weight of a drying oil such as linseed oil, soybean oil, 0-80% by weight of a solvent such as normal paraffin, isoparaffin, aromatic hydrocarbon, naphthene, α-olefin or a mixture thereof It is preferable to comprise 1 to 5% by weight of additives such as dryers and drying inhibitors (total of 100% by weight excluding UV absorbers).

  When coating by gravure printing method, excluding UV absorber, acrylic resin, vinyl chloride-vinyl acetate copolymer, polyester resin, urethane resin, chlorinated polyolefin resin, chlorinated rubber resin, ethylene-vinyl acetate copolymer 20-50% by weight of at least one resin selected from coalesced, polyamide resin, cellulose resin and the like, and esters such as ethyl acetate, butyl acetate and isobutyl acetate, aliphatic and aromatic such as heptane, toluene and benzene It is preferably composed of 50 to 80% by weight of a general-purpose solvent such as hydrocarbons, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and alcohols such as methanol, ethanol and propanol (a total of 100% by weight excluding the ultraviolet absorber).

  Next, as a UV curable overprint varnish (UVOP varnish, UV high gloss varnish) composition used in a UV curing system that is dried by ultraviolet (UV) irradiation, a photosensitive resin oligomer (prepolymer) and a photoreactive dilution are used. It is obtained by constituting a vehicle with a monomer as an agent and adding a photopolymerization initiator (photosensitizer) or the like to the vehicle.

  As the oligomer, an oligomer having a radical polymerizable unsaturated group in the molecule, for example, a polyester acrylate resin, a urethane acrylate resin, a polyether acrylate resin, or the like is used.

  The overprint varnish composition can be applied by a known printing method such as an offset printing method, a gravure printing method, a silk screen printing method, or a known coating method such as a gravure roll coating method or a reverse roll coating method. Of these, an offset printing method and a gravure printing method are preferred because the coating amount is uniformly stable and delicate coating amount adjustment is easy. Moreover, since the coated overprint varnish composition forms a substantially colorless and transparent film after drying, the printing quality of the printing ink layer (2) is not impaired.

  The ultraviolet absorber (4) is preferably contained in a proportion of 0.1 to 10% by weight based on the solid content of the overprint varnish composition.

  Next, when the packaging material having ultraviolet cut-off properties according to the present invention is formed into a bag-made product or the like, a sealant layer (not shown) can be formed on the inner surface of the base sheet (1). The material used for the sealant layer is not particularly limited as long as it is a thermoplastic resin that can be sealed by heat sealing or the like. For example, low density polyethylene resin (LDPE), medium density polyethylene resin (MDPE) , High density polyethylene resin (HDPE), linear low density polyethylene resin (L-LDPE), ethylene-α resin such as ethylene-α-olefin copolymer, homopolypropylene resin, propylene-ethylene random copolymer, propylene-ethylene Polypropylene resins such as block copolymers and propylene-α-olefin copolymers can be selected, and modified polyolefin resins obtained by acid-modifying these olefin resins by graft polymerization or the like can also be used. The above-mentioned polyolefin resin alone or a blended product composed of two or more kinds may be used.

  For the method of forming the sealant layer, a thermoplastic resin film prepared by previously forming the resin is used, and a method of forming through an adhesive layer and an extrusion in which a thermoplastic resin is directly melt extruded and laminated. There is a method of forming by a lamination method (melt extrusion lamination method). It is preferable that the thickness of the sealant layer is arbitrarily selected within a range of about 20 to 100 μm.

  Further, when the packaging material having ultraviolet cut-off property according to the present invention is required to have sufficient resistance against oxygen gas, water vapor, etc., depending on the contents to be stored, a barrier laminated film (not shown) is used as the base material. It laminates | stacks through the contact bonding layer (not shown) in the middle of a sheet | seat (1) and a sealant layer.

  Examples of the barrier laminate film include an inorganic oxide vapor-deposited film in which a vapor-deposited thin film layer of an inorganic oxide is laminated on a support film (not shown) such as a polyethylene terephthalate (PET) film, polyethylene terephthalate (PET), Polyamide (PA), polypropylene (PP) and other films coated with polyvinylidene chloride, biaxially stretched polyethylene terephthalate, biaxially stretched nylon film and ethylene-vinyl alcohol copolymer laminated film, Films such as ethylene-vinyl alcohol copolymer film (EVOH), polyvinyl alcohol film (PVA), saponified ethylene-vinyl acetate copolymer (EVA), or a combination of one or more of these films Laminated layer Beam and the like.

It is a sectional side view which shows one Example of the laminated constitution of the packaging material which has the ultraviolet cut property which concerns on this invention. It is a figure which shows one Example of the chemical structural formula of the ultraviolet absorber which consists of a hydroxyphenyl triazine type compound (HPT) used for the packaging material which has the ultraviolet-cut property based on this invention. It is a graph which shows the absorption characteristic of the ultraviolet absorber which consists of a hydroxyphenyl triazine type compound (HPT) used for the packaging material which has the ultraviolet-cut property based on this invention. It is a sectional side view which shows one Example of the layer structure of the packaging material which has the conventional ultraviolet cut property. It is a figure which shows one Example of the chemical structural formula of the ultraviolet absorber which consists of a benzotriazole (BTZ) type compound (BTZ) used for the packaging material which has the conventional ultraviolet cut property. It is a graph which shows the absorption characteristic of the ultraviolet absorber which consists of a benzotriazole (BTZ) type compound (BTZ) used for the packaging material which has the conventional ultraviolet cut property.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material sheet 2 ... Printing ink layer 3 ... Overprint varnish layer 4 ... Ultraviolet absorber

Claims (2)

  A packaging material comprising a base sheet mainly composed of paper, the overcoat provided by covering the base sheet, a printing ink layer on an outer surface of the base sheet, and a printing surface including the printing ink layer A packaging material having an ultraviolet cut property, wherein the overprint varnish layer comprises an overprint varnish composition containing an ultraviolet absorber comprising at least a hydroxyphenyltriazine compound. .   The packaging material having an ultraviolet cutting property according to claim 1, wherein the ultraviolet absorber is contained in a proportion of 0.1 to 10% by weight based on the solid content of the overprint varnish composition. .

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