JP2779291B2 - Print laminating film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print laminating film used for protecting the surface of printing paper or the like.

[0002]

2. Description of the Related Art Lamination of a film on a printing paper is widely practiced for the purpose of protecting the surface of the printing paper, imparting water resistance or oil resistance, or improving the surface gloss. As a film for print lamination used for such purpose, a stretched polypropylene film is often used as a base film, and a solvent-type ethylene-vinyl acetate copolymer adhesive is often used as an adhesive layer. However, in the method using a solvent type adhesive, it is necessary to pay particular attention to the solvent recovery and the working environment from the point of handling the solvent, and it is generally necessary to consider the pot life from the point of using the curing agent.

[0003] In order to improve such a defect, a print laminating film having a solventless type heat-bonding layer formed thereon has already been proposed (for example, Japanese Patent Application Laid-Open No. Sho 57-1466).
No. 53), among which, an adhesive layer mainly composed of an ethylene / vinyl acetate copolymer is mainly used.
However, in a product obtained by laminating such a film on a printing paper, the so-called tunneling phenomenon, in which the laminated film is eroded by the residual solvent caused by the printing ink and the film peels in a tunnel shape, may occur.
In particular, to facilitate the production of laminated films,
This tendency was remarkable when a lubricant or an anti-blocking agent was added to the adhesive layer or when a low molecular weight polymer was added to improve the adhesive performance. If a low molecular weight polymer is not blended, the desired adhesive strength cannot be obtained without processing at a relatively high temperature when laminating the film to the printing paper, resulting in poor productivity and curling of the paper or ink. Problems such as discoloration occurred, and the rubber roll used was damaged quickly, so that it was necessary to replace it early. Also, the gloss of the resulting product was not always satisfactory. Furthermore, it was pointed out that other problems such as insufficient adhesiveness with a stretched polypropylene film as a base film.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present inventors
Based on these problems, a non-solvent type adhesive having excellent adhesiveness to a base film or printing paper and a reduced tendency to cause a tunneling phenomenon without substantially sacrificing laminating processability. Was examined. As a result, it has been found that a film for print lamination satisfying all such requirements can be obtained by using an adhesive layer as described later, and the present invention has been achieved.

[0005]

According to the present invention, one side of a base film has a vinyl acetate content of 25 to 40% by weight.
The ethylene / vinyl acetate copolymer of Example 1 is grafted with 0.1 to 4% by weight of an unsaturated carboxylic anhydride, and has a melt flow rate (190 ° C., 2160 g load) of 1 to 100 g /
5 to 30% by weight of the graft modified product (A) for 10 minutes, 10 to 25% by weight of vinyl acetate, and 95 to 70% by weight of ethylene / vinyl acetate copolymer having a melt flow rate of 3 to 50 g / 10 minutes. The present invention provides a print laminating film provided with an adhesive resin layer.

[0006] The base film in the present invention includes polypropylene, polyethylene, poly-4-methyl-1-
A stretched or non-stretched transparent film of pentene, polyester, polyamide, polyvinyl chloride or the like is used. Generally, a biaxially stretched film is preferably used from the viewpoint of good transparency and strength, and particularly, a biaxially stretched polypropylene, a biaxially stretched polyethylene terephthalate, and a biaxially stretched polyvinyl chloride are preferably used. Although the thickness is arbitrary, it is generally preferable to use one having a thickness of about 10 to 50 μm. In the base film, additives such as a lubricant, an antiblocking agent, a stabilizer, an antioxidant, an antistatic agent, a colorant, and an ultraviolet absorber may be blended.

In the present invention, a graft-modified ethylene-vinyl acetate copolymer (A) (hereinafter sometimes referred to as a graft-modified product (A)) and an ethylene-vinyl acetate copolymer An adhesive layer made of the polymer (B) is provided.

The graft modified product (A) is prepared by adding 0.1 to 4% by weight to an ethylene / vinyl acetate copolymer having a vinyl acetate content of 25 to 40% by weight, preferably 28 to 35% by weight.
Preferably, the melt flow rate grafted with 0.5 to 2% by weight of unsaturated carboxylic anhydride is 1 to 100 g.
/ 10 minutes, preferably 2 to 40 g / 10 minutes. Ethylene as the base polymer of the graft-modified product
Even if the vinyl acetate content of the vinyl acetate copolymer is smaller than the above range, a product excellent in low-temperature adhesion to printing paper cannot be obtained, and the content of the vinyl acetate copolymer larger than the above range is not considered. If used, problems arise in heat stability, blocking resistance, and adhesion to printing ink, so that it is not preferable.

Further, those having a small graft amount of unsaturated carboxylic anhydride do not show improvement in adhesion to the base film and tunneling resistance, and when the graft amount is too large, the base film may not be improved. It is not preferable because the processability at the time of laminating is reduced. Here, examples of the unsaturated carboxylic anhydride include maleic anhydride, itaconic anhydride, norbornene-2,3-dicarboxylic anhydride, and the like. Is most preferred.

It is not preferable to use a graft-modified product (A) having a melt flow rate smaller than the above range, since the processability upon laminating the base film is lowered. The use of is not preferred because the adhesiveness is reduced.

The component (B) of the present invention has a vinyl acetate content of 10 to 25% by weight, preferably 15 to 23% by weight, and a melt flow rate of 3 to 50 g / 10 minutes, preferably 10 to 30 g / 10 minutes. Use When the one having a vinyl acetate content smaller than the above range is used, the low-temperature adhesiveness to printing paper is reduced, and when the content exceeds the above range, the heat resistance is insufficient, and the base film is insufficient. Since the laminating temperature must be lowered during lamination, high-temperature processing cannot be performed, and at the same time, the adhesiveness to the printing ink decreases. Further, if the melt flow rate is smaller than the above range, high-speed processing is similarly difficult, and if the melt flow rate is larger than the above range, the heat-resistant adhesive strength is undesirably reduced.

The blending ratio of the graft-modified product (A) to the ethylene / vinyl acetate copolymer (B) is 5-30% by weight, preferably 7-20% by weight, and 95-70% by weight.
%, Preferably 93 to 80% by weight. If the former ratio is less than the above range, the effect of improving the adhesiveness and tunneling resistance is not sufficient, and if the ratio is too high, the laminating property deteriorates, and neither is preferable.

In the adhesive resin composition comprising (A) and (B), the above-mentioned additives or low-molecular polymers can be arbitrarily compounded similarly to the base film. The blending of the low molecular weight polymer is effective for improving the gloss and the feeling, but on the other hand, it is a factor that impairs the tunneling resistance. Therefore, it should not be blended in a large amount. For example, (A) and (B) It is preferable that the content be about 5 parts by weight or less per 100 parts by weight of both components.

The film for print lamination in the present invention is generally produced by subjecting the adhesive resin composition to a base film by melt lamination. Of course, it can be manufactured by a co-extrusion method,
When the base film is a stretched film, it can be produced by stretching a co-extruded film.

When the adhesive resin composition is melt-laminated on a substrate film, it is preferable that the substrate film is previously subjected to a surface treatment such as a corona treatment or an anchor coating agent is applied. . As the anchor coating agent, for example, a polyolefin or isocyanate can be used. The melt lamination process should be performed at a speed as high as possible and in consideration of the thermal stability of the adhesive layer. Generally, a temperature of 150 to 230 ° C. is employed. The thickness of the adhesive layer can be arbitrarily selected in consideration of the adhesive strength, crushing, gloss and the like, but is usually in the range of 3 to 50 μm, preferably 8 to 30 μm.

The thus obtained print laminating film is thermocompression-bonded to the surface of various printing papers for the purpose of improving the appearance, protecting the surface, imparting water resistance and oil resistance, and for other purposes. At this time, corona treatment, ozone treatment,
Although it is preferable to perform a surface treatment such as a frame treatment, a corona treatment is particularly simple and effective. The corona treatment is performed, for example, at a temperature of 90 ° C. or less and a wetting tension of 36 dyne / c.
m or more, especially 38 dyne / cm or more. When using the print laminating film of the present invention, the thermocompression bonding temperature is relatively low, for example, 80 to
Even when bonded at a temperature of 110 ° C, particularly 80 to 100 ° C, it is possible to obtain a processed paper having a high bonding strength and no tunneling phenomenon. Also, the interlayer adhesive strength between the base film and the adhesive layer is excellent, and the workability in laminating is also excellent. Further, there is an advantage that a processed paper having excellent surface gloss and good crushing can be easily produced.

[0017]

EXAMPLES The following examples will specifically explain the influence on the quality of a printed paper laminate product based on the change in the composition and the mixing ratio of the graft modified product (A) and the ethylene / vinyl acetate copolymer (B). . The raw materials used in the examples and comparative examples,
The compounding method, laminating method, evaluation method of the bonded product and the like are as follows.

1. Adhesive raw materials The following were used as adhesive raw materials. (1) Modified graft (A): Modified maleic anhydride graft of ethylene / vinyl acetate copolymer

(2) Ethylene / vinyl acetate copolymer (B)

(3) Low molecular weight polymer (C) Terpene phenol resin having a molecular weight of 700

2. Mixing of Adhesive The above-mentioned adhesive raw materials and an alkylphenol-based stabilizer at a ratio of 0.5% by weight were mixed well in a blender, and then melt-extruded into pellets to obtain laminate raw materials.

3. Extrusion Laminating An adhesive layer having a thickness of 12 μm was laminated by extrusion lamination on a biaxially oriented polypropylene having a thickness of 15 μm treated with an anchor coat agent, followed by corona treatment to provide a film for print lamination.

4. Print laminating (lamination) The printing surface of coated paper having a printing surface with five colors of offset printing of gold, black, red, blue, and yellow, and the above-mentioned film, a sheet heat roll generally used in the gloss processing industry. Roll temperature 80 ° C and 110 ° C, roll pressure 100k with a laminating machine
The bonding was performed under the conditions of g / cm ² and bonding conditions of 30 m / min.

5. Evaluation method of bonded product Evaluation of the bonded product was performed by the following method. (1) Adhesive strength JIS Z 1707 Peeling angle 180 ° Peeling speed 300mm / min Material piece width 25mm Atmospheric temperature 23 ° C Atmospheric humidity 65%

(2) Gloss JIS Z8741 Angle 60 °

(3) Ink peeling property, ink removal The film is peeled off from the printing paper which has been subjected to print lamination, and the degree of peeling of the printing ink at the peeled part is visually evaluated. Peel off and the paper becomes almost pure white ○… ７０ 70% ~ 90% The pattern on the paper can be found △… ４０ 40% ~ 70% The pattern on the paper becomes clear ×…… Less than 40% Ink slightly on the film side Migration

(4) Degree of curl The central part of the printed paper subjected to print lamination is 30 cm × 3
Cut to 0 cm, place the film side up and evaluate by the rising dimension of both sides ○: 5 mm or less △: 5 to 10 mm ×: 10 mm or more

(5) Tunneling property 100 μl of light oil was dropped with a micro syringe on the non-bonded surface of the printing paper which had been subjected to print lamination, and was left in an atmosphere of a temperature of 23 ° C. and a humidity of 65%. Observation and evaluation of changes in surface ◎ No problem with adhesion and appearance at all ○ Adhesion is slightly reduced but there is no change in appearance (to the extent that it can be used) △ Slightly bumpy × Tunneling clearly occurs

Examples [1 to 15] Graft modified products (2) to (5), copolymer (2) and, if necessary, low molecular weight polymer were blended in various blending ratios as shown in Table 1. Using the adhesive, print lamination was performed on the offset printing paper according to the above method, and the physical properties of the bonded product were evaluated. Table 2 shows the results.

[0030]

[Table 1]

[0031]

[Table 2]

[Comparative Examples 1 to 9] Examples using adhesives obtained by blending the graft-modified product (1) and copolymers (1) to (3) at various blending ratios shown in Table 3 Printed and laminated on offset printing paper in the same manner as in Nos. 1 to 15, and the physical properties of the bonded product were evaluated. Table 4 shows the results.

[0033]

[Table 3]

[0034]

[Table 4]

As is clear from the results in Table 2, in print lamination on offset printing paper, Example 1 was used.
Nos. 15 to 15 have good adhesive strength, ink removal, and tunneling properties.

Further, as a result of performing the test on UV ink print coated paper or printed synthetic paper, which is considered to be more difficult to adhere by print lamination, those of Examples 1 to 15 showed similarly good characteristics. In particular, Example 3 exhibited good adhesion to solid printing on synthetic paper. In the case of Example 13, the tunneling was slightly poor, but the adhesion to all printed portions was excellent. The texture of Example 15 was very good.

On the other hand, as shown in Table 4, the performance of the comparative example was slightly poor as a whole, and among them, the performance of the comparative example 6 which was relatively good was inferior in adhesiveness to synthetic paper.

[0038]

The film for print lamination according to the present invention uses the graft-modified ethylene / vinyl acetate copolymer (A) and the ethylene / vinyl acetate copolymer (B) as the adhesive resin layer. A printed laminated paper having high adhesive strength and no tunneling phenomenon even when thermocompression-bonded at a relatively low temperature can be obtained. Also, the interlayer adhesive strength between the base film and the adhesive layer is excellent, and the workability in laminating is also excellent. Further, since the physical properties of the processed paper such as surface gloss are excellent, it is useful for print lamination of various publications, posters, paper containers and the like.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09J 123/08 C09J 123/08 123/26 123/26 (56) References JP-A-57-146653 (JP, A) JP-A JP-A-54-144477 (JP, A) JP-A-63-254035 (JP, A) JP-A-59-75914 (JP, A) JP-A-3-12280 (JP, U) (58) Fields investigated (Int) .Cl. ⁶ , DB name) C09J 7/00-7/04 B32B 27/00-27/42

Claims (4)

(57) [Claims] 1. A melt in which an unsaturated carboxylic anhydride of 0.1 to 4% by weight is grafted onto an ethylene / vinyl acetate copolymer having a vinyl acetate content of 25 to 40% by weight on one side of a substrate film. Modified graft (A) 5 having a flow rate (190 ° C., 2160 g load) of 1 to 100 g / 10 min.
An adhesive resin layer comprising 95 to 70% by weight of an ethylene / vinyl acetate copolymer (B) having a vinyl acetate content of 10 to 25% by weight and a melt flow rate of 3 to 50 g / 10 minutes. Print lamination film. 2. The film for print lamination according to claim 1, wherein the adhesive resin layer contains 5 parts by weight or less of a low molecular weight polymer per 100 parts by weight of the total amount of both components (A) and (B). 3. The print laminating film according to claim 1, wherein the substrate film is surface-treated or coated with an anchor coating agent. 4. The film for print lamination according to claim 1, wherein the adhesive resin layer is surface-treated.