JPH01299885A - Metallized paper - Google Patents

Abstract

PURPOSE:To obtain a metallized paper which does not form cracks, wrinkles or the like even when immersed in water, by forming a metal pigment-containing electron beam-curable resin layer on a base paper of a limited elongation in water and curing this layer by irradiation with electron beams. CONSTITUTION:This metallized paper is obtained by forming a layer of a composition formed by adding a metal pigment to an electron beam-curable resin on a base paper of a lateral elongation in water <=2.5% and curing this layer by irradiation with electron beams. The base paper used is one having an elongation in water in the lateral direction in paper making <=2.5%, desirably, 1.5%, and such a paper can be obtained in the following way. Namely, the ratio of the tensile strength Y (kg) in the lateral direction in paper making to the tensile strength T (kg) in the direction of flow X 100 (x=Y/TX100) is to 70-130%, desirably, 80-120%. A base paper having such a special value can be obtained by varying the directionality of pulp fibers in paper during paper making.

Description

Detailed Description of the Invention: "Industrial Application Field" The present invention relates to metallized paper that is attached to beer bottles, etc., and is concerned with metallized paper that is attached to beer bottles, etc. This invention relates to metallized paper that has been improved in the occurrence of cracks (cracks) and wrinkles in the metallized layer.

``Prior art'' Conventionally, paper for labels pasted onto beer bottles, etc., has been paper made by laminating art boat paper or art coated paper with metal foil such as aluminum foil. Bonded label paper was widely used because of its excellent product appeal.

However, in recent years, label paper laminated with aluminum foil is gradually being replaced by metal-deposited paper, label paper having a resin layer containing metal pigments, that is, a metallized layer, and the like. This means that when comparing metallized paper, metalized paper, and label paper laminated with aluminum foil, the amount of aluminum used in metallized paper is 1/100 of that of label paper laminated with aluminum foil.
This is because of the advantages of resource saving and cost reduction, as well as good printability and cutting workability. In addition, since beer bottles in particular are collected and reused, they are treated with chemicals during the bottle washing process.
At this time, it reacts with aluminum and generates hydrogen gas, so the smaller the amount of aluminum used, the better the working environment and safety will be, so the use of metallized paper and the like is becoming more widespread.

However, manufacturing metallized paper requires a vacuum evaporation device, and in order to maintain a vacuum during the evaporation process, pretreatment is required to prevent the generation of volatile substances from the base paper. In order to obtain a metallic luster, it is necessary to smoothen the base paper, and furthermore, there is a drawback that the production process is complicated, such as requiring humidity control treatment to prevent curling after vapor deposition.

On the other hand, metallized paper in which a resin layer containing a metal pigment is formed on a base paper is produced, for example, by diluting an aluminum paste or a synthetic resin such as an alkyd resin containing an aluminum pigment with an organic solvent and applying it to the base paper. In this case, since the organic solvent drying process requires a long time, production efficiency is low and a large amount of energy is consumed.Furthermore, since a solvent is used, there are problems such as fire outbreaks and adverse effects on the human body.

Attempts have also been made to blend aluminum paste or aluminum pigment into a resin emulsion and use it as a water-based coating composition. In this case, although safety is improved, there are problems such as difficulty in dispersing the metal pigment, poor metallic luster, and a large amount of energy required for the drying process.

For this reason, a manufacturing method has been proposed in which a coating layer made of an electron beam curable resin containing no organic solvent and an aluminum pigment is formed on a base paper, and the metallized layer is cured with an electron beam (Japanese Patent Laid-Open No. 61-238870). .

However, metallized paper produced by either method has the following problems when used. That is, when a beer bottle or the like with metallized paper attached to the bottle is immersed and cooled in a refrigerator or water, fine cracks and wrinkles occur in the metallized layer.

"Problems to be Solved by the Invention" The present invention provides metallized paper that does not cause cracks or wrinkles in the metallized layer even when immersed in water, etc., and does not have problems due to the use of organic solvents or water. The purpose is to

[Means for Solving the Problems J] The present invention provides a metallized paper in which a layer of a composition material containing an electron beam curable resin and a metal pigment is formed on a base paper, and the core layer is cured by electron beam irradiation. , is a metallized paper characterized in that the base paper has an underwater elongation in the lateral direction of 2.5% or less.

"Function" As a result of studying the cranks and wrinkles that occur in metallized paper, the inventors found that when metalized paper is attached as a label to a beer bottle, etc., and is immersed in cold water or placed in a refrigerator, the label becomes It was discovered that the elongation of the base paper due to wetting is much greater than that of the metallized layer, which causes strain and causes cracks and wrinkles in the metallized layer. In order to suppress this distortion, it is necessary to reduce the elongation of the base paper in water, and by using a base paper with a horizontal elongation in water of 2.5% or less, cracks and wrinkles can be prevented. I found out that it is possible.

The base paper used in the present invention has an underwater elongation of 2.
The paper content is 5% or less, preferably 1.5% or less.

Specifically, such a base paper is obtained as follows.

(b) The ratio X (formula 0) of the tensile strength Y (kg) in the transverse direction of the base paper and the tensile strength T (kg) in the machine direction is 70 to 13.
Adjust to 6%, preferably 80 to 120%.

X=Y/TxlOO(χ)...■ Paper made under normal papermaking conditions has a tensile strength T in the machine direction that is much larger than the tensile strength Y in the transverse direction.
The tensile strength ratio X expressed by the above formula 0 is 60% or less,
Most of the paper is 30-50%. The reason for this is thought to be that the pulp fibers are oriented in the flow direction. When such paper uses a normal drying process, the vertical elongation in water is approximately 1% or less, but the horizontal underwater elongation is very large, sometimes reaching 5% or more. .

As mentioned above, the base paper used in the present invention has a tensile strength ratio X of To
-130%, preferably 80-120%, and base papers with such special values are obtained by changing the orientation of the pulp fibers on the paper machine. The orientation of the pulp fibers is influenced by shaking on the wire and drawing during the drying process, but is mainly controlled by appropriate speed settings of the slicing jet and the wire.

In other words, compared to a slicing jet, when the wire speed is increased, the fibers tend to line up in the machine direction, and the tensile strength in the machine direction becomes stronger.On the other hand, when the wire speed is slowed down, the fibers tend to line up in the lateral direction, and the fibers tend to line up in the lateral direction. The tensile strength of the material is strengthened.

Therefore, the base paper as described above is made by mainly setting the slice jet and wire speeds appropriately depending on each paper machine. In addition, the tensile strength ratio X is 140%
If it becomes too thick, the texture of the paper will deteriorate significantly, which is not desirable.

The base paper obtained by the above method has an underwater elongation of 2.5 in the transverse direction even if a normal drying process is used.
% or less, and those with 1.5% or less can also be sufficiently manufactured.

(b) Use tension drying paper. Paper shrinks significantly in the lateral direction in the drying section during papermaking, but the tension-dried paper described here is paper that is dried by applying tension in the lateral direction during drying to suppress paper shrinkage.

For example, a wet paper web is brought into close contact with the surface of a large-diameter cylinder dryer with a finely polished surface, such as a Yankee dryer, using a pressure roll, and then dried to suppress the shrinkage of the paper in the lateral direction. So-called kataneshi paper was made in this way.

Further, strain-dried paper includes paper manufactured by so-called press drying, which is a method of contact drying by applying external pressure at a temperature of 100° C. or higher in a moisture range of 40 to 70% moisture in the paper web.

If pre-drying is performed using a drying device such as a multi-cylinder cylinder dryer before tension drying, it has the advantage of increasing the papermaking speed, but since lateral shrinkage occurs during pre-drying, pre-drying The lateral underwater elongation is greater than when the material is directly strain-dried using a Yankee dryer or the like.

Tension-dried paper has a transverse underwater elongation of 2.5% or less,
It is also possible to sufficiently manufacture products with a content of 1.5% or less.

The tensile strength ratio X is adjusted by adjusting the orientation of the valve fibers on the paper machine.
Particularly excellent crack prevention effects can be obtained by strain-drying a material in which the ratio is 70 to 130%.

Next, an electron beam curable resin composition containing a metal pigment is applied onto the base paper and cured by irradiation with an electron beam to form a metallized layer. Aluminum powder, bronze powder, etc. are used as the metal pigment.

Furthermore, if a paste is used in which a metal pigment is mixed with stearic acid or the like, it is convenient to handle and can be easily dispersed.

There are two types of metallic pigments: leafing and non-leafing. Leafing types float on the surface of the coating layer and are arranged in parallel, while non-leafing types are uniformly dispersed throughout the coating layer. Because of its properties, it is easier to obtain a strong metallic luster with the former, and when using the latter, a calm and mysterious metallic luster can be obtained.

The electron beam curable resin used in the present invention is not particularly limited as long as it is a resin that can be cured by electron beams, but it is composed of the following prepolymers and monomers, for example.

(1) Prepolymers include (a) poly(meth)acrylates of aliphatic, alicyclic, and araliphatic di- to hexavalent polyhydric alcohols and polyalkylene glycols; (b) aliphatic, alicyclic, Aroaliphatic, aromatic 2-6
(C) poly(meth)acryloyloxyalkyl phosphate; (d) polyester poly(meth)acrylate;
(e) Epoxy poly(meth)acrylate; (f)
Polyurethane poly(meth)acrylate; (2)
Polyamide poly(meth)acrylate; (11) Polysiloxane poly(meth)acrylate; (i) Vinyl-based or diene-based low polymer having a (meth)acryloyloxy group in the side chain and/or terminal; (j) Said ( The oligoesters described in a) to (i) (
meth)acrylate modified products, etc.

(2) Monomers include (a) Carboxyl group-containing monomers represented by ethylenically unsaturated mono- or polycarboxylic acids, and carboxylic acid group-containing monomers such as their alkali metal salts, ammonium salts, and amine salts. body; (b) ethylenically unsaturated (
An amide group-containing monomer represented by vinyl lactams such as meth)acrylamide or alkyl-substituted (meth)acrylamide, and N-vinylpyrrolidone; (C) A sulfonic acid group represented by aliphatic or aromatic vinyl sulfonic acids. sulfonic acid group-containing monomers and their alkali metal salts, ammonium salts, amine salts, etc.; (d) hydroxyl group-containing monomers represented by ethylenically unsaturated ethers; (e) dimethyl Amino group-containing monomer such as amine ethyl (meth)acrylate-2-vinylpyridine; (f)
Quaternary ammonium base-containing monomers; (bound) alkyl esters of ethylenically unsaturated carboxylic acids; (h) nitrile group-containing monomers such as (meth)acrylonitrile; (i) styrene; (j) vinyl acetate, acetic acid ( Esters of ethylenically unsaturated alcohols such as meth)allyl; (g) Mono(meth)acrylates of alkylene oxide addition polymers of compounds containing active hydrogen; (1) Diesters of polybasic acids and unsaturated alcohols; Representative ester group-containing bifunctional monomer: (e) Bifunctional monomer consisting of a diester of an alkylene oxide addition polymer of an active hydrogen-containing compound and (meth)acrylic acid; (n) N, N -Bisacrylamides such as methylenebisacrylamide; (0) Difunctional monomers such as divinylbenzene, divinylethylene glycol, divinylsulfone, divinyl ether, and divinyl ketone; Φ) Typical examples include polyesters of polycarboxylic acids and unsaturated alcohols. (q) A polyfunctional monomer consisting of a polyester of an alkylene oxide addition polymer of a compound containing active hydrogen and (meth)acrylic acid; (r) A polyfunctional monomer containing an ester group, such as trivinylbenzene. polyfunctional unsaturated monomer.

etc.

In the present invention, 1 to 4 metal pigments are added to the electron beam curable resin.
An electron beam curable resin composition is prepared by adding 0%, preferably 10 to 30%. If the amount of the metal pigment added is less than 1%, it is difficult to obtain a sufficient metallic luster, and if it exceeds 40%, the thixotropy of the composition may increase and the applicability may be poor.

The composition material containing the electron beam curable resin and the metal pigment is applied onto the base paper by a conventional coating method such as a bar coater, roll coater, air knife coater, or gravure coater. In addition, the coating amount is 0.3 to 30 g/rrf in terms of dry weight.
is preferable, and more preferably 1 to 15 g/rrr. At this time, if the coating amount is less than 0.3g/rrf, sufficient metallic luster cannot be obtained, and if it is more than 30g/rrf, it is not only economically disadvantageous, but also, depending on the resin used, the label may become too hard, making it difficult to cut. However, there are disadvantages in that the label is difficult to dissolve and peel off during the bottle washing process.

The dose of the electron beam to be irradiated is preferably in the range of about 0.1 to 2Q Mrad, preferably about 0.5 to 1Q Mrad. If it is less than 0°l Mrad, the resin component cannot be sufficiently cured, and if it exceeds 2Q Mrad, the strength of the base paper may decrease.

Examples of electron beam irradiation methods include scanning method,
A curtain beam method, a broad beam method, etc. can be adopted, and an appropriate acceleration voltage for irradiation is 100 to 300 KV.

Note that a paint layer containing pigment and adhesive as main components can be provided on the base paper in order to increase smoothness and improve gloss. In addition, if an undercoat layer mainly composed of synthetic resin is provided between the base paper and the metallized layer, or between the paint layer and the metallized layer if a paint layer is provided, the smoothness of the base paper can be further improved. It is possible to suppress excessive penetration of the electron beam curable resin composition material into the base paper. Examples of synthetic resins used in the undercoat layer include alkyd resins, acrylic resins, vinyl resins, cellulose resins, urethane resins, resins, and polyester resins, which can be dissolved in a solvent or aqueous medium. Or disperse and apply. Further, electron beam curing type or ultraviolet curing type resin can also be used.

In order to prevent metal oxidation, prevent metal pigments from falling off, provide scratch resistance, and abrasion resistance on the formed metallized layer, or to improve suitability for post-processing such as printing, it is necessary to apply coatings on the metallized layer. A top coat layer may be provided. As the top coat layer, the same synthetic resin or electron beam curing resin as used for the undercoat layer can be used.

The manufacturing process of the metallized paper of the present invention is simpler and the production efficiency is higher than that of metallized paper. In addition, compared to the case of using a solvent-based or water-based resin composition containing metal pigments, the electron beam-cured resin layer has a higher crosslinking density, so it has the effect of further reducing the expansion and contraction of the base paper, and reduces cracks in the metallized layer. The occurrence can be further prevented. In addition, the electron beam cured resin layer has high smoothness, so it has excellent metallic luster, and is also excellent in safety and production efficiency.

"Example" The present invention will be described in more detail with reference to Examples below, but of course the scope is not limited thereto. Further, "part" and "%J" in the examples indicate "part by weight" and "% by weight", respectively.

Example I A paper stock prepared by adding 1.5 parts of rosin size, 5 parts of talc, and 3 parts of aluminum sulfate to a pulp composition of 60 parts of NBKP and 40 parts of LBKP was dried in a paper machine using only a Yankee dryer in the drying process. The paper was dried to obtain tension-dried paper with a weight of 50 g/rrr. Note that the underwater elongation of this base paper in the lateral direction was 1.0%.

The dry coating amount of acrylic emulsion was 4 on this base paper.
g/n+'' to form an undercoat layer.

Next, add 70 parts of electron beam curable resin (RadiCure 78E204, manufactured by Mobil Chemical) to 30 parts of leafing type aluminum paste (Alpaste 231M, manufactured by Toyo Aluminum ■) (contains 21 parts of non-volatile components). The electron beam curable resin composition obtained by mixing and dispersing was applied onto the undercoat layer at 6 g/rrr, and irradiated with an electron beam of 3 Mrad using an electron beam irradiation device (Electro Curtain CB150, manufactured by ESI). A metallized paper was obtained by forming a metallized layer.

Example 2 A paper stock prepared by adding 1.5 parts of rosin size, 5 parts of talc, and 3 parts of sulfuric acid to a pulp composition of 15 parts of NBKP and 85 parts of LBKP was machined using a long paper machine, paying attention to the alignment of the pulp fibers, and rolling it in the transverse direction. Paper was made by adjusting the ratio of tensile strength in the machine direction and tensile strength in the machine direction to 95%. In addition, in the drying process, a normal multi-cylinder cylinder dryer was used. The transverse underwater elongation of this base paper was 1.4%. Next, a metallized layer was formed in the same manner as in Example 1 to obtain metallized paper.

Example 3 Using the same paper stock as in Example 2, paper was made using a Fourdrinier paper machine with the ratio of tensile strength in the transverse direction and in the machine direction adjusted to 75%. A normal multi-cylinder cylinder dryer was used in the drying process. The horizontal elongation in water of this base paper is 2.0
%Met. Next, a metallized layer was formed in the same manner as in Example 1 to obtain metallized paper.

Comparative Example 1 Using the same stock as in Example 1, paper was made under normal conditions on a long paper machine equipped with a multi-cylinder cylinder dryer. The ratio of the tensile strength in the transverse direction and the machine direction of the obtained base paper was 4.
0%, and the lateral underwater elongation was 4.2%. Next, a metallized layer was formed in the same manner as in Example 1 to obtain metallized paper.

Comparative Example 2 A similar undercoat layer was formed on the same base paper as in Example 1, and aluminum paste (trade name: Alpaste 231M) was applied on this undercoat layer.

(manufactured by Toyo Aluminum) 100 parts (contains 70 parts of non-volatile components)
200 parts of styrene-butadiene latex (solid content concentration 50%), 30 parts of starch, 200 parts of water, and 1 part of anionic surfactant with a dry weight of 6 g/m'' A metallized layer was formed by coating and drying to obtain metallized paper (no electron beam irradiation was performed).

Each metallized paper obtained as above was placed in a 2 cm x 4
Cut it into 1/4 inch pieces, apply casein glue in stripes, stick it on a beer bottle, let it air dry for 24 hours, then soak it in water for 4 hours.
After 8 hours of immersion, the appearance of cranks and wrinkles on the surface of the metallized layer was visually determined.

The evaluation was performed 10 times for each sample, and the results are shown in Table 1.

In addition, the gloss of the metallized layer surface was visually determined, and the results are shown in Table 1.

〔Evaluation criteria〕

Office of Kuo Ri ◎... No cracks or wrinkles are observed.

O: Almost no cracks or wrinkles are observed.

×...Cranks and wrinkles were generated on the entire surface of all samples.

Gold layer gloss O: Very good Δ: Slightly inferior "effect" The present invention was a metallized paper that did not generate cracks or wrinkles, had excellent metallic luster, and was easily produced.

Claims (3)

[Claims] (1) In metallized paper, which is obtained by forming a layer of a composition material containing an electron beam curable resin and a metal pigment on a base paper, and curing the layer by electron beam irradiation, the base paper is expanded in the lateral direction in water. A metallized paper characterized by having a content of 2.5% or less. (2) The metallized paper according to claim (1), characterized in that a base paper having a ratio X of tensile strength Y in the transverse direction to tensile strength T in the machine direction expressed by the following formula is 70 to 130%. X=Y/T×100(%) (3) The metallized paper according to claim (1), wherein the base paper is a strain-dried paper.