JPS59222873A - Metalized paper for label - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of industrial application) The present invention relates to a metallized paper for labels designed to be easily washed in an alkaline solution bath.

Labels used on bottles that are collected and reused, such as beer bottles, must not peel off even when immersed in water at home and can be easily removed when washing the bottles after collection. be done. In particular, recently aluminum foil-laminated paper has been increasingly used to improve appearance.

A common method is to treat the collected bottles in a warm alkaline bath to dissolve the alkaline-easily soluble adhesive and remove the labels.

(Prior Art) However, there are three problems with this aluminum foil laminated paper. The first problem is the problem of hydrogen generation in the bottle washing process.
The second problem is workability when pasting labels, and the third problem is that it takes time to remove labels when washing bottles.

In the bottle washing process, labels using aluminum foil-laminated paper often pose problems as a large amount of hydrogen gas is generated when aluminum is dissolved in alkaline solution, resulting in the risk of explosion due to ignition and negative effects on the working environment. . In addition, after printing on aluminum foil laminated paper, when stacking 500 to 1,000 sheets and punching them into a label mold, due to the nature of aluminum foil, the cross sections stick together, making it difficult to "sort". There are also problems with workability when pasting tags, such as picking up multiple sheets at the same time when pasting tags on bottles.

As one method for solving this problem, it has been proposed to use aluminum vapor-deposited paper, for example, as disclosed in Japanese Patent Application Laid-Open No. 154494/1983.

The thickness of aluminum in aluminum vapor-deposited paper is usually very thin, 0.02 to 0.1 pm, and is less than 1/100 of the thickness of aluminum foil, which is 10 to 20μ+71. Because of this, the generation of hydrogen gas in the alkaline solution bath is also small. The present inventors have also confirmed that the workability when pasting tags is good.

Therefore, although the first and second problems have been solved, the third problem remains unresolved, and its solution has been strongly desired.

(Purpose of the invention) The bottle washing process is usually carried out using approximately 4% sodium chloride soda at a liquid temperature of 70 to 80.
It is common to wash the bottle at ℃ for 7 to 8 minutes, then rinse with water and dry. In particular, remove the label as quickly as possible, for example 6
If the stripping is done within minutes, the work can be carried out in a controlled manner within a predetermined period of time even if there is some variation due to liquid temperature or a drop in alkaline concentration.

During the washing time, the cleaning solution soaks in from around the label and dissolves the adhesive, but it also removes the vapor deposited layer, resin layer, etc. from the label surface.
It depends on the time it takes for the cleaning solution to soak through the base paper and dissolve the adhesive. Above all, it depends on the properties of the resin layer.

The present inventors have made extensive research into creating a label that can be peeled off within a predetermined time in an alkaline solution bath, and in particular have studied the characteristics of the resin, leading to the present invention.

(Structure of the Invention) That is, the present invention provides a metallized paper for labels in which a base paper, a resin layer (hereinafter referred to as a first resin layer), and an aluminum vapor-deposited layer are sequentially laminated, in which the resin layer has an acid value of 40 or more. The present invention relates to metallized paper for labels, which is characterized by the following.

Furthermore, the metallized paper for labels is further provided with a resin layer (hereinafter referred to as a second resin layer) on the aluminum vapor-deposited layer, if necessary. The role of this layer is to prevent aluminum from forming an oxide film if left for a long time after aluminum evaporation, which may reduce adhesion with ink during printing in the subsequent process.
There is a way to prevent this. In such a configuration, the object of the present invention can be achieved only when the co-acid values of the first and second resin layers are 40 or more.

Acid value generally refers to the number of potassium hydroxide required to neutralize free fatty acids contained in fats and oils, but in the present invention, it mainly refers to the amount of carboxyl groups in the resin containing carboxyl %. This uses acid value as an index.

After understanding the present invention, it is determined by back titration with a hydrochloric acid solution.

In the present invention, it is important that the acid value of each of the first and second resin layers is 40 or more, and if the acid value of either layer is less than 40, the object of the present invention is achieved. I can't do that.

The resin used in the present invention is not particularly limited as long as the resin layer has an acid value of 40 or more, but examples of preferred resins include acrylic resins containing carboxyl groups, polyester resins, and vinyl acetate resins. Examples include one or a combination of two or more of styrene-butadiene copolymer resins and styrene-butadiene copolymer resins. In addition, if the apparent acid value of a resin made by combining said resin as a main component with a resin that does not contain a carboxyl group is within the range of the present invention, the object can be achieved. There are also protein-based resins such as shellac and casein, but since these are natural products, their quality is not stable, and shellac tends to deteriorate over time after aluminum is deposited, and the adhesive strength of the aluminum decreases. It has the disadvantage that it peels off and crumbles when used with cellophane tape.

Examples of carboxyl group-free resins used in combination with carboxyl group-containing resins in the present invention include nitrocellulose, acetyl cellulose, melamine resins, polyurethane resins, polycarbonate resins, and the like.

These fats are used for the purposes of improving gloss, improving the strength of the coating layer, and improving adhesion to the aluminum layer.

The metallized paper for labels referred to in the present invention has a resin layer (first resin layer) as a first layer on one side of the base paper, and further has an aluminum vapor deposited layer as a second layer on one side of the base paper. A resin layer (second resin layer) is sequentially provided as a third layer. When used as a label, it is further printed in 3 to 6 colors by gravure printing, offset printing, etc., and then punched out into a predetermined shape.

In order to peel off the label in an alkaline bath, it is preferable that the first and second resin layers other than aluminum and the printing ink layer dissolve quickly.

Of course, these resins and inks must be insoluble or dissolvable in the water for which the label is intended to be used.In order to produce the metallized paper for labels according to the present invention, the base paper is high-quality paper,
Medium-quality paper, pure white roll paper, art paper, coated paper, lightweight coated paper, paper mixed with synthetic fibers, paper mixed with glass fiber, etc. are used.

The first resin layer has a coating thickness of 1 to 25 μm, preferably 3 to 15 μm.
Coated in the μm range. The second resin layer is provided as necessary, and has a thickness of 0.1 to 15 μm, preferably 0.
．． It is coated in a range of 5 to 7 μm.

The resin is prepared as a solvent-soluble, water-soluble, or emulsion-like coating, which is coated and dried using a gravure coater, bar coater, reverse roll coater, blade coater, air knife coater, or the like. Aluminum is usually vapor-deposited at a vacuum level of 10' to 10''twnHfi' to a thickness of about 200 to 1,000 layers.

(Effects of the Invention) When the metallized paper for labels of the present invention is used, the bottle washing time can be significantly shortened compared to conventional paper.

(Example) Next, the present invention will be explained using examples.

Example 1 Acrylic 4 with acid value 40 on the coated side of 609 single-sided coated paper
(After applying Ll fat to a thickness of 52β (solid content, same hereinafter) using a gravure coater and drying, aluminum was applied by vacuum deposition to a thickness of !1l1500.

Furthermore, a maleic acid resin with an acid value of 120 is applied on top of it using a gravure coater at 1°5f//;r? A metallized paper for labels was obtained. The obtained paper was printed with a printing ink containing maleic acid resin and nitrified cotton (1:2 ratio) as a vehicle (gravure printing), and then a punched label was obtained.The resulting label was coated with casein glue. After leaving the label on a beer bottle for one day, the label was immersed in a 4% caustic soda solution at 70°C and slowly moved 9 times to measure the time until the label peeled off. Separately, after the label paper was left for one day after printing, the adhesion of the vapor-deposited surface was checked using cellophane tape. The results are shown in Table 1. Example 2: A polyvinyl acetate resin with an acid value of 60 and a maleic acid resin with an acid value of 120 were blended on the coated side of 602 single-sided coated paper in a ratio of 1:1). After coating with a gravure coater and drying, the following steps were carried out in the same manner as in Example 1. The results are shown in Table 1.

Example 3 Maleic acid resin with an acid value of 120 and nitrified cotton were blended on the coated side of 601 single-sided coated paper in a ratio of 5:1, with an apparent acid value of 100) 10? /w? After coating with gravure caulk and drying, the following steps were carried out in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 An acrylic resin having an acid value of 30 was coated on the coated side of 602 single-sided coated paper using a gravure coater for 95 seconds, and after drying, the following steps were carried out in the same manner as in Example 1. The results are shown in Table 1.

Claims (2)

[Claims] (1) In metallized paper for laminated labels with base paper and wood 1 (layer 1 and aluminum vapor deposition), the acid value of the wood layer is 40 or more. Metalized paper for labels. (2) In metallized paper for labels made by sequentially laminating a base paper, a resin layer, an aluminum vapor-deposited layer, and a jugetsuma layer, 4
☆1 Metallized paper for labels, characterized in that the acid value of the oil layer is 40 or more.