JP2909155B2 - Aluminum evaporated paper - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum-coated paper used for beer bottles, spark paper (for cigarettes), and the like, and more particularly, to the deposition of aluminum-coated paper stored in a wound state. The present invention relates to an aluminum-evaporated paper improved so that a synthetic resin and a vapor-deposited layer exhibit good adhesion when a layer is overcoated with a synthetic resin.

[Background Art] Aluminum vapor-deposited paper is widely used as label paper for sake, beer, soft drinks, etc., spark paper, wrapping paper for confectionery, and the like. There are two types of methods for producing aluminum-evaporated paper used for such purposes, a direct method and a transfer method. The direct method is a method in which a resin is undercoated on a base paper or a base paper coated with an aqueous coating composition on the base paper (hereinafter, these are simply referred to as “base paper”), and a resin is vapor-deposited thereon. . On the other hand, the transfer method is a method in which a release layer is formed on a plastic film, aluminum is vapor-deposited on the release layer, and then laminated with a base paper via an adhesive, and the vapor-deposited layer is transferred to the base paper.

The surface of the aluminum layer obtained by the direct method or the transfer method (except when the release layer also serves as a protective layer) is generally coated with a resin to protect the vapor deposition surface. Originally, the surface of the aluminum layer immediately after vapor deposition is chemically active and has good adhesion to the resin coating treatment. However, in both the direct method and the transfer method, the vapor-deposited paper is temporarily stored in a wound state before being coated with the resin, and in such a case,
As time passes, the surface of the aluminum vapor-deposited layer does not show good adhesiveness. This phenomenon is considered to be due to the fact that when the surface of the aluminum layer comes into contact with the back surface of the vapor-deposited paper, that is, the back surface of the base paper, contaminants transfer from the back surface of the vapor-deposited paper to the aluminum layer surface and contaminate the surface.
Therefore, a method of coating a PVA resin on the backside of the vapor-deposited paper to provide a barrier layer to prevent the transfer of contaminants (Japanese Patent Application Laid-Open No. 56-140197), using a base paper containing a specific sizing agent to reduce the contamination of the aluminum layer surface. Reduction processing (Japanese Unexamined Patent Publication No. 61-24693)
Etc. have been proposed. However, these methods cannot sufficiently prevent the transfer of contaminants to the surface of the active aluminum vapor-deposited layer, and there is a strong demand for an aluminum-deposited paper having significantly improved adhesion of the overcoating resin.

"Problems to be Solved by the Invention" The present invention significantly reduces the adhesiveness to synthetic resin that occurs when a synthetic resin coating is applied to the surface of aluminum-evaporated paper stored in a wound or stacked state. To provide an improved aluminum vapor-deposited paper.

"Means for Solving the Problems" The present invention provides an aluminum-evaporated paper having an aluminum-evaporated layer provided on a base paper, wherein the spontaneous polarization potential value of the surface of the aluminum-evaporated layer measured by the following method is 0.
An aluminum-evaporated paper characterized by using a base paper whose back surface is treated with an alkaline material so as to be in a range of -1100 mV (vs. calomel electrode).

"Measurement method of spontaneous polarization potential value" The surface of the aluminum vapor-deposited layer formed on the polyester film and the back side of the backed base paper are superposed facing each other under the same conditions as when provided on the base paper. During,
After leaving for 3 hours under a pressure of 50 g / cm ² , a 0.1 M-phosphate buffer solution (pH 7.0) at a liquid temperature of 30 ° C. was used as an electrolyte solution, an aluminum deposition layer as a working electrode, a calomel electrode as a standard electrode, Measure the potential using a platinum electrode as the counter electrode, and after starting the measurement
Value after 60 seconds.

"Operation" In the direct method or the transfer method, after the aluminum deposition layer is provided on the base paper, the surface of the aluminum deposition layer that has been left for a long time in the wound or stacked state has an adhesive property with the overcoating resin. As mentioned above, the phenomenon of the remarkable decrease in the temperature was observed. However, when aluminum is vapor-deposited on a polyester film or the like, the above-described remarkable decrease in adhesiveness is not observed even when the film is left in a wound state for a long time.

From such a phenomenon, the present inventors have paid attention to the fact that the surface of the aluminum vapor deposition layer stored in a wound or stacked state and the back surface of the base paper are in face-to-face contact with each other in a pressurized state. Vapor deposition (the conditions for vapor deposition are the same as those for vapor deposition on the target base paper, and the same applies hereinafter when a vapor deposition layer is provided on a film).
(B) no contact with the surface after deposition,
(B) As a result of evaluating the adhesiveness of the aluminum layer surface to the overcoating resin after applying a pressure of 50 g / cm ² for 3 hours in an atmosphere of 50 ° C. by bringing the base paper and (c) into contact with a polyester film, (B) Compared to the state where nothing was contacted and (c) the state where the polyester film was contacted, (b) when the base paper was contacted, a remarkable decrease in adhesion was observed. As a result, it was found that by using this method, the adhesiveness of the aluminum-evaporated surface left in the wound state to the overcoating resin could be evaluated.

Based on these findings, the present inventors have conducted intensive studies and studies on the surface characteristics of various base papers and aluminum deposited layers. It has been found that there is a great relation to the decrease in resin adhesion that occurs in the state. That is, the spontaneous polarization potential value of the vapor-deposited layer surface measured after pressing the aluminum vapor-deposited layer and the back surface of the base paper under specific conditions is 0 to 1100.
Completed the present invention by using a base paper whose back surface has been treated with an alkaline material so that it is within the range of mV (vs. calomel electrode). It was done.

The spontaneous polarization potential value is a unique value that varies depending on various metals, and reflects a change in the surface of the metal due to oxidation or corrosion, or a change in the surface state due to adhesion of gas or oil. Therefore, when the spontaneous polarization potential value of the surface of the aluminum deposition layer in contact with the back surface of the base paper subjected to various treatments is evaluated with respect to the spontaneous polarization potential value of the surface of the active aluminum deposition layer immediately after the deposition, the change in the surface state is evaluated. You can know. Therefore, by appropriately treating the back surface of the base paper that is in contact with the aluminum-deposited layer surface, the adhesiveness between the aluminum-deposited layer surface and the overcoating resin layer can be improved.

The reason why such a superior effect can be obtained by performing a specific back surface treatment is that the back surface treatment eliminates contaminants on the surface of the aluminum vapor-deposited layer, or a substance contained in the processing solution. It is considered that this is because it adhered to the surface of the aluminum vapor-deposited layer and prevented adhesion of contaminants from the base paper.

By the way, when the processing that the natural polarization potential value does not fall within the range of 0 to 1100 mV (vs. calomel electrode),
The aluminum deposited layer is heavily contaminated, and as a result, the adhesion of the overcoating resin cannot be improved.

The measurement conditions of the spontaneous polarization potential value are as follows: 0.1 M-phosphate buffer (pH 7.0) whose solution temperature is maintained at 30 ° C. is used as an electrolyte solution.
Aluminum electrode layer (evaporated on polyester film) for evaluation on working electrode, calomel electrode on standard electrode,
A platinum electrode was used as a counter electrode. The value 60 seconds after the start of measurement was taken as the spontaneous polarization potential value in consideration of the time required for the voltage to stabilize.

In the present invention, the back surface is treated with an alkaline material so that the spontaneous polarization potential value of the surface of the aluminum vapor-deposited layer after superposition is in the range of 0 to 1100 mV (vs. calomel electrode), preferably -800 to -1100 mV. This is very important.
Therefore, the alkaline material used for the treatment of the back surface of the base paper is not particularly limited as long as the spontaneous polarization potential value satisfies the above-mentioned conditions. For example, caustic soda, sodium carbonate, sodium bicarbonate, polyacrylic acid, etc. Alkaline materials such as soda are more preferably used, and at least one of them is used as an aqueous solution having a concentration of about 1 to 10% by weight, and the back surface may be coated with 3 to 20 g / m ² . Also, if necessary, a small amount of inorganic or organic pigments,
It can also be added to the processing solution. In the present invention, the object can be achieved by treating only the back side of the base paper, but the front side of the base paper (that is, the surface on which the vapor deposition layer is provided).
May be subjected to the same processing.

As the base paper used in the present invention, a base paper or a coated paper in which a coating layer mainly composed of a pigment and an adhesive is provided on the base paper can be appropriately applied. In addition, such base papers are generally high-quality paper, various types of mechanical pulp (BCTMP, CTMP, SGP, RGP, etc.), DIP
Medium paper or neutral base paper containing
A base paper of about 100 g / m ² is used, but these are not particularly limited.
There is no particular limitation.

On the base paper thus treated, in the direct method,
An undercoat layer and an aluminum deposition layer are sequentially formed. In the transfer method, an aluminum layer deposited on a plastic film is transferred to a base paper provided with an undercoat layer.

The undercoat layer is provided for the purpose of imparting smoothness to paper so that the aluminum vapor-deposited layer provided thereon has excellent metallic luster, and increasing the adhesive strength between the vapor-deposited layer and the base paper. Such an undercoat layer is a layer containing a synthetic resin as a main component, and the synthetic resin used is roughly classified into a solvent type, an aqueous type and a non-solvent type. Generally, a solvent-based material is used because of its excellent quality. Specific examples of the resin include an alkyd resin, an acrylic resin, a vinyl resin, a cellulose resin, a urethane resin, and a polyester resin. In addition, various resins may be appropriately modified to be easily soluble in alkali and used in an aqueous system. As for the coating method, coating is performed with a commonly used coating machine such as a roll coater, a reverse coater, a gravure coater, a cast coater, a bar coater and the like.

In the present invention, the deposition amount of aluminum is preferably about 0.01 to 0.1 μm from the viewpoint of appearance and cost.

Furthermore, on the aluminum deposition layer, in order to enhance the post-processing suitability such as oxidation, prevention of contamination and printing of the metal deposition surface,
An overcoat layer is provided. The overcoat layer is also formed mainly of a synthetic resin, but the same resin as the undercoat layer is appropriately selected and used according to the application, and the coating method is not particularly limited as in the case of the undercoat layer.

"Examples" Hereinafter, the present invention will be described more specifically with reference to examples, but is not limited thereto. In the examples, "parts" and "%" indicate "parts by weight" and "% by weight", respectively, unless otherwise specified.

[Evaluation Method 1 for Adhesion of Overcoating Resin] The back surface of the treated base paper was brought into face-to-face contact with the surface of the aluminum layer immediately after being vapor-deposited on the polyester film, sealed with a plastic bag, and a load of 50 g / cm ² was applied. For 3 hours. Next, 1.5 g / m ² of an acrylic resin (trade name: ALMIC W, manufactured by Dainichi Seika Co., Ltd.) was applied to the aluminum surface, dried at 90 ° C. for 60 seconds, and then printed with a red printing ink (TOKASH
It was printed with IKISOCHEMICAL INDUSTRY CO., LTD. SD Super Deluxe 50 red B (manufactured by Akira Seisakusho), and the state of peeling of the overcoating resin was visually judged.

：: Not peeled at all ×: Peeled [Evaluation method of adhesion of overcoating resin 2] Aluminum coated paper after overcoating
The state of peeling of the overcoating resin when a commercially available cellophane tape was adhered and peeled was visually judged.

○: Not peeled at all ×: Peeled Example 1 Rosin size in pulp formulation of 60 parts of NKNK and 40 parts of LKP
The stock prepared by adding 1.5 parts, 5 parts of talc and 3 parts of sulfuric acid band was paper-dried with a paper machine using only a Yankee dryer to obtain a base paper of 50 g / m ^{2 in} rice tsubo.

Separately, 100 parts of kaolin (trade name: UW-90, manufactured by EMC) and 0.2 parts of sodium hexametaphosphate were used to prepare a pigment slurry having a solid content of 70% using a Cores dispersing machine. To this pigment slurry, 3 parts (solid content) of oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) and 15 parts (fixed amount) of styrene / butadiene copolymer latex were added, and water was further added to obtain a solid concentration of 60%. % Of the coating solution was prepared. The coating liquid was applied and dried using a bend blade coater in which the base paper was turned off on the smooth surface side so that the coating amount after drying was 20 g / m ² . Resulting Subsequently, using two kiss roll coater sodium 1% carbonate aqueous solution 15 g / m ² and Nurihi the back surface and dried in an air foil dryer on one side coated paper in the paper moisture 6.5% Was. Then, smoothing treatment was performed by a super calender to obtain a base paper for aluminum vapor deposition. Using this base paper, the spontaneous polarization potential value and the adhesiveness of the overcoating resin were evaluated by [Evaluation Method 1]. Further, on this base paper, an acrylic resin is coated with a gravure coater so that the coating amount after drying is 4 g / m ² to form an undercoat layer, and aluminum is coated on the undercoat layer by a vacuum evaporation machine. Evaporation was performed to a thickness of 0.05 μm, and one day later, an acrylic overcoat resin was applied to prepare a rolled aluminum evaporated paper. The adhesiveness of the overcoating of this vapor-deposited paper was evaluated by [Evaluation method 2], and these evaluation results are shown in Table 1.

Example 2 A base paper and an aluminum-evaporated paper were obtained in the same manner as in Example 1 except that the 1% aqueous sodium bicarbonate solution for the back surface treatment was changed to a 1.5% aqueous sodium carbonate solution. The evaluation results are shown in Table 1. Was.

Example 3 A base paper was obtained in the same manner as in Example 1 except that the 1% aqueous sodium bicarbonate solution for the back surface treatment was changed to a 1% aqueous sodium hydroxide solution. Using this base paper, the spontaneous polarization potential value and the adhesiveness of the overcoating resin were evaluated by [Evaluation method 1].

Separately, a release agent was applied to the polyester carrier film by gravure coating, and aluminum was deposited on the coated surface to a thickness of 0.05 μm. The vapor-deposited surface is bonded to the base paper obtained above via a urethane-based adhesive, the carrier film is separated after aging, and one day later, an acrylic overcoat resin is applied and rolled up. It was created. The adhesiveness of the overcoating of the deposited paper was evaluated by [Evaluation method 2].
The evaluation results are shown in Table 1.

Comparative Example 1 A base paper and an aluminum-evaporated paper were obtained in the same manner as in Example 1 except that the back surface treatment was not performed, and the evaluation results are shown in Table 1.

Comparative Example 2 Base paper and aluminum-evaporated paper in the same manner as in Example 1 except that the 1% aqueous sodium bicarbonate solution for the backside treatment was changed to a 5% aqueous solution of polyvinyl alcohol (trade name: PVA-105, manufactured by Kuraray Co., Ltd.). And the evaluation results are shown in Table 1.

"Effects" As is apparent from Table 1, the aluminum-evaporated paper of the present invention is an excellent vapor-deposited paper having a good adhesion between the aluminum-evaporated surface and the overcoating resin even when left in a wound state. there were.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) D21H 19/02-19/08

Claims (1)

(57) [Claims] An aluminum-evaporated paper comprising an aluminum-evaporated layer provided on a base paper and having a spontaneous polarization potential value of 0 on the surface of the aluminum-evaporated layer measured by the following method.
An aluminum-evaporated paper using a base paper whose back surface is treated with an alkaline material so as to be in a range of -1100 mV (vs. calomel electrode). "Measurement method of spontaneous polarization potential value" The surface of the aluminum vapor-deposited layer formed on aluminum formed on the polyester film under the same conditions as when it is provided on the base paper, and the back surface of the base paper that has been subjected to the back processing are superposed facing each other. After leaving for 3 hours in an atmosphere of 50 ° C. under a pressure of 50 g / cm ² , a 0.1 M phosphate buffer (pH 7.0) at a liquid temperature of 30 ° C. was used as an electrolyte solution, and an aluminum deposition layer was formed on the working electrode. ,
The potential was measured using a calomel electrode as the standard electrode and a platinum electrode as the counter electrode, and a value 60 seconds after the start of the measurement.