JPH0578510A - Polyolefin film having excellent offset printing suitability - Google Patents

Abstract

PURPOSE:To provide a polyolefin film which is less apt to develop a surface roughness or to curl throughout the whole film even when printed by offset printing with a widely used offset ink of the oxidative polymerization type (drying ink). CONSTITUTION:The objective film comprises a polyolefin film coated on either or both sides with an organic acid ester of a higher aliphatic alcohol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin film having excellent offset printability, which prevents the film from becoming uneven or curled by the vehicle in the offset ink even when offset printing is performed.

[0002]

2. Description of the Related Art Lithography, which is generally called offset printing, can be easily used for multicolor printing and is therefore used for printing paper, polyethylene terephthalate film, polyamide, coated paper and the like. In particular, a general-purpose dry offset ink is composed of the compositions shown in Tables 1 and 2 shown below.

[0003]

[Table 1]

[0004]

[Table 2]

The above-mentioned vehicle is a liquid portion of the components constituting the printing ink, in which the pigment is dispersed to give fluidity to the ink, and on the printing machine, from the ink fountain to each roller, the plate,
Its function is to smoothly transfer to the printing surface via a blanket and to change to a solid after printing to fix the pigment to the printing surface. Linseed oil type, alkyd type, quick drying resin type, heat It is classified as a set type. In particular, in recent years, in order to improve the printing speed, it is required to shorten the drying time of the offset ink. Therefore, a resin and a mineral oil (high boiling point petroleum solvent) were mixed with a drying oil as a vehicle of the ink. Quick-drying ink is used. However, using these quick-drying offset inks, a synthetic paper made of a stretched product of a polyolefin film or a film containing inorganic fine powder in polyolefin (Japanese Patent Publication No. 46-40794, JP-A No. 61-279).
No. 543, No. 61-3748, etc.), the polyolefin is swollen by the vehicle (particularly high boiling point petroleum solvent such as mineral oil) of the offset ink used for quick-dry offset printing. When unevenness is partially generated on the surface of the printed film, or when printing is performed on the entire surface of the film, so-called solvent attack occurs, such as curling of the entire film, so it is difficult to actually use was there. Therefore, as the offset printing ink for a polyolefin film, a special offset ink for a polyolefin film, which is not blended with mineral oil at the expense of quick-drying property, is actually used.

[0006]

However, since such a special offset ink for polyolefin film has a long drying time and a limited number of printers and ink manufacturers, it is of a general oxidation polymerization type (dry oil type). The advent of polyolefin films that can use offset inks has been desired. That is, a general printing company prints pulp-based paper such as high-quality paper and coated paper, and it is common to perform offset printing using a quick-drying ink that is commercially available. Only when printing film or synthetic paper, it was necessary to switch to a special offset ink for non-absorbent materials and print. Therefore, since it takes a lot of time and labor to switch the ink, general printing companies do not actively try to print polyolefin-based films such as synthetic paper, and this is due to this fact. Was one of the causes that hindered its widespread use in offset printing. On the other hand, in order to solve these problems, the present inventors have conducted extensive studies and previously proposed to apply mineral oil or higher fatty acid ester, which is a component of the ink, to one side or both sides (special feature). See Japanese Patent Application No. 2-176606 and Japanese Patent Application No. 2-176607).

[0007]

[Means for Solving the Problems]

[Summary of the Invention] As a result of further intensive studies, the present inventors have found that, similar to the previous invention, a vehicle of ultraviolet ink is applied to a surface of a polyolefin film or a polyolefin-based synthetic paper on which offset printing is to be performed. The acrylic or methacrylic acid ester of higher aliphatic alcohol that is also used as a part of or the organic acid ester of higher aliphatic alcohol having a composition close to that is pre-coated and allowed to penetrate, and then offset printing is performed. The present invention was completed based on the finding that even if offset ink is applied to the surface, unevenness will occur on the surface of a printed polyolefin film or synthetic paper, and curl will not occur on the entire film. It has come to do. That is, the polyolefin film having excellent offset printability of the present invention is characterized in that one or both surfaces of the polyolefin film are coated with an organic acid ester of a higher aliphatic alcohol. Further, in order to further enhance the effect of the present invention, the organic acid ester of the higher aliphatic alcohol is applied, and then electron beam irradiation or ultraviolet irradiation is performed.

[Detailed Description of the Invention] [I] Polyolefin Film with Excellent Offset Printability (1) Structure The polyolefin film with excellent offset printability according to the present invention comprises a higher aliphatic alcohol on one or both sides of the film. It has a structure in which an organic acid ester is applied and at least a part of the organic acid ester of a higher aliphatic alcohol is impregnated in the inside. Therefore, the organic acid ester of higher aliphatic alcohol applied to the surface of the film and the organic acid ester of higher aliphatic alcohol impregnated to the inside of the film are present in the film. (2) Amount ratio The amount of the organic acid ester of higher aliphatic alcohol applied to the surface is generally 0.1 to 20 g / m ² , and preferably 1 to 3 g / m ² . Particularly, as the organic acid ester of higher aliphatic alcohol capable of exhibiting the effect of the present invention, since it is impregnated into the inside of the film, the higher aliphatic alcohol impregnated into the inside of the film. The amount of the organic acid ester is important.

[II] Method for producing polyolefin film having excellent printability (1) Raw material polyolefin film As a polyolefin film used as a raw material for the polyolefin film having excellent printability of the present invention,
It is a film (including a sheet) having a wall thickness of 20 to 500 μm obtained by molding a polyolefin resin by various film molding methods. Specifically, a small amount of polyolefin resin such as polyethylene, polypropylene, ethylene / propylene copolymer resin, polybutene resin, ethylene / vinyl acetate copolymer resin, ethylene / acrylic ester copolymer resin, etc. An olefin copolymer obtained by copolymerizing (1.8 to 15% by weight) another comonomer is formed by a film forming method such as a casting method, a uniaxial stretching method or a biaxial stretching method. The obtained polyolefin film, or an opaque or translucent synthetic paper having microvoids on the surface, which is obtained by mixing a small amount of an inorganic filler in the film and then stretching the mixture (Japanese Patent Publication No. 46- 40794
(See Japanese Patent Publication) and the like. Among these polyolefin films, particularly, 8 to 65% by weight of organic or inorganic fine powder in a polyolefin resin obtained by polymerizing or copolymerizing a monomer containing ethylene, propylene or both as main components in an amount of 50% by weight or more. A so-called synthetic paper obtained by uniaxially or biaxially stretching a polyolefin film containing an organic or inorganic fine powder containing is preferable in terms of printability.

Organic acid ester of higher aliphatic alcohol As the organic acid ester of higher aliphatic alcohol, which is used as a raw material of the polyolefin film having excellent printability of the present invention and is coated and impregnated on the surface of the polyolefin film, It is an ester, diester or mixture of higher aliphatic alcohols having 8 or more carbon atoms. Specifically, capric alcohol, lauryl alcohol, cilistin alcohol, palmityl alcohol,
Stearyl alcohol, behenyl alcohol, oleyl alcohol, linole alcohol and other higher aliphatic alcohols having 8 or more carbon atoms and acetic acid, propionic acid, butyric acid, benzoic acid, acrylic acid, methacrylic acid, maleic acid, fumaric acid and the like, preferably 2 carbon atoms. ~ 6 esters with organic acids. Among these, esters of higher aliphatic alcohols selected from stearyl alcohol, lauryl alcohol, and oleyl alcohol with lower fatty acids (particularly unsaturated) selected from acrylic acid, methacrylic acid, maleic acid, fumaric acid, and itaconic acid are particularly preferred. Preference is given to using.

(2) Coating (impregnation) coating A polyolefin film having excellent printability according to the present invention is obtained by coating the surface of the above-mentioned raw material polyolefin film with the above-mentioned organic acid ester of a higher aliphatic alcohol. It can be produced by impregnating the inside with an organic acid ester of a higher aliphatic alcohol. To apply the organic acid ester of the higher aliphatic alcohol to the surface of the polyolefin film,
When the organic acid ester of the higher aliphatic alcohol has a high viscosity and is difficult to apply, various diluents such as toluene, xylene and mineral spirits can be used. Application method As a method of applying the ester of higher aliphatic alcohol to the surface of the polyolefin film, specifically, known coating methods such as gravure coating, Meyer bar coating, roll coating, and blade coating. The method can be adopted. In addition to coating, the polyolefin film may be dipped and impregnated in a tank of an organic acid ester solution of higher aliphatic alcohol. Coating amount The coating amount is generally in the range of 0.1 to 20 g / m ² , preferably 1 to 3 g / m ² . 60 to 1 after coating
It is preferable to dry at a temperature of 50 ° C., particularly 80 to 120 ° C. for about 1 minute. Impregnation (drying) The above-mentioned coated polyolefin film has a slightly moist feel because the ester of the higher alcohol applied is a liquid, and after leaving it for a long time to allow it to sufficiently permeate into the polyolefin, it becomes a dry state. Used as.

(3) Electron Beam Irradiation or Ultraviolet Irradiation In order to shorten such long-term standing, it is recommended to carry out electron beam irradiation or ultraviolet irradiation after coating and drying. When the ultraviolet irradiation is performed, it is necessary to add a photoinitiator to the organic acid ester of higher aliphatic alcohol in advance.

(4) Other Additional Treatments Further, pigment coating can be applied onto the film to further improve the suitability for offset printing.
The pigment coating can be applied according to the general coating of coated paper. As the pigment, clay, talc, calcium carbonate, magnesium carbonate, aluminum hydroxide, silica, aluminum silicate, calcium silicate, plastic pigment, silica-containing composite latex and the like which are commonly used for coated paper can be used. As the adhesive used at this time, latex such as SBR (styrene-butadiene rubber), MBR (methacryl-butadiene rubber), acrylic emulsion, starch, PVA (polyvinyl alcohol), CM
Examples thereof include C (carboxymethyl cellulose) and methyl cellulose.

[III] Offset Printing The thus obtained polyolefin film having excellent offset printing properties of the present invention is subjected to offset printing by adhering offset ink to the surface thereof in an offset printing machine. (1) Offset ink Generally, such an offset ink is shown in Table 1 above.
Further, as shown in Table 2, it is basically composed of a main agent composed of a pigment and a vehicle, and an auxiliary agent composed of a viscosity modifier, a drying modifier and the like. As the pigment,
Azo pigments such as resole red and benzidine yellow,
Lake pigments such as permanent grin, permanent rhodamine, permanent blue, lake red C, brilliant carmine 6B, organic pigments such as phthalocyanine blue, alumina, barium sulfate, red iron oxide,
Inorganic pigments such as yellow lead, navy blue, titanium white, carbon black and the like can be mentioned. Examples of the vehicle include synthetic resin, vegetable oil (drying oil), solvent and the like. Specific examples of these vehicles include linseed oil type such as linseed oil and stand oil, alkyd type such as drying oil-modified alkyd resin, rosin-modified phenolic resin, linseed oil and millet oil mixture, or low-viscosity linseed oil. Dissolves in oil varnish, etc.,
A quick-drying resin type mainly composed of a resin varnish whose viscosity is adjusted by adding a petroleum fraction having a narrow boiling point range, a heat-set type such as a varnish obtained by dissolving a resin by adding a petroleum fraction having a narrow boiling range range, etc. You can Examples of the viscosity modifier include solvents, diluted varnishes, compounds and the like. Further, examples of the drying conditioner include a drying agent (dryer) drying inhibitor. Examples of other components include waxes, film enhancers, and anti-backing agents.

(2) Offset printing method In order to perform offset printing on the polyolefin film having excellent offset printability of the present invention using the above-mentioned offset ink, a commercially available offset printing machine is used in the same manner as ordinary offset printing. Can be done. Thus obtained polyolefin film having excellent printability of the present invention is subjected to offset printing, and even if an offset ink is attached to the surface thereof, unevenness occurs on the surface of the printed polyolefin film or synthetic paper. It is unlikely that the entire film will curl.

[0016]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples below. The parts and% in the examples are on a weight basis unless otherwise specified. In addition, the evaluations in Examples and Comparative Examples were evaluated by the following evaluation methods. Evaluation method (1) Curl height Using a new best one process ink M (manufactured by Toka Dye Co., Ltd.) which is a dry type offset ink commercially available in an offset printing machine as an evaluation film, the transfer amount is 1 g / m ² . Print on the entire surface so that And the printed matter is 12 cm
After being cut to a size of 5 cm and left on a flat desk for 1 day, the curl height (h) of the printed matter was measured as shown in FIG. (2) Occurrence of unevenness A transfer amount of 1 g / m ² was obtained by using New Best One Process Ink M (manufactured by Toka Dye Co., Ltd.), which is a dry offset ink commercially available in an offset printing machine, on the evaluation film. The same ink was partially printed so as to form a one-pine pattern (1 cm x 1 cm). Then, the unevenness of the film formed between the printed portion and the non-printed portion was judged by sensory evaluation. The one with no unevenness was marked with O, the one with severe unevenness was marked with X, and the middle thereof was marked with Δ. (3) The ink dryness evaluation film was printed on the entire surface and was not printed on the printing surface. Synthetic paper manufactured by Oji Yuka Synthetic Paper Co., Ltd.
PG80 ″ (trade name; wall thickness: 80 μm) is placed, and a line is drawn on the YUPO FPG80 with a ballpoint pen every unit time. The time at which the printing ink does not set off is defined as the ink drying time.

Experimental Example 1 A solution of stearyl methacrylate dissolved in toluene at 30% by weight on the surface of a high-density polyethylene film produced by an inflation molding method was used with a Meyer bar 10
A polyethylene film coated with liquid paraffin was obtained by applying a coating amount of g / m ² and drying at a temperature of 80 ° C. for 3 minutes, and further applying the same application to the back surface. The obtained polyethylene film is subjected to full-scale printing with a dry offset ink and printing of a checkerboard pattern, and the curl height,
Occurrence of irregularities and evaluation of ink drying property were performed. The results are shown in Table 3.

Comparative Example 1 Printing was performed in the same manner as in Example 1 except that stearyl methacrylate was not applied, and the curl height of the printed matter was measured in the same manner as in Example 1. The results are shown in Table 3.

Example 2 Polypropylene "Mitsubishi Noblen MA-6 manufactured by Mitsubishi Petrochemical Co., Ltd."
A composition comprising 98 parts of "(trade name, melting point 164 ° C.) and 2 parts of Maruo calcium heavy calcium carbonate powder" Maruo Super 5S "(trade name) was melt-kneaded using an extruder,
A sheet was extruded from the die at a temperature of 200 ° C., and then stretched 5 times at 155 ° C. in the longitudinal direction and 8 times at 155 ° C. in the transverse direction to obtain a single-layer biaxially stretched synthetic paper (thickness 60 μm).
The single-layer biaxially stretched synthetic paper was printed in the same manner as in Example 1, and the curl height of this printed matter was measured in the same manner as in Example 1.

Comparative Example 2 Printing was performed in the same manner as in Example 2 except that stearyl methacrylate was not applied, and the curl height of the printed matter was measured in the same manner as in Example 1. The results are shown in Table 3.

Example 3 Mitsubishi Yuka Polypropylene "Mitsubishi Noblen MA-6"
"(Trade name, melting point 164 ° C) 80 parts, high-density polyethylene" Yucaron Hard EY-40 (trade name, melting point 130
℃) "10 parts and Maruo calcium heavy calcium carbonate powder" Maruo Super 5S "(trade name) 10 parts of the composition was melt-kneaded using an extruder, and then 200
It was extruded in sheet form at a temperature of 0 ° C and the sheet was cooled to a temperature of about 50 ° C. Then heat this sheet to approximately 135 ° C.
After heating to the vertical direction, use the peripheral speed difference of the rolls to
The film was stretched twice. On the other hand, 60 parts of polypropylene “Mitsubishi Noblen MA-3” (trade name, melting point 164 ° C.) manufactured by Mitsubishi Petrochemical Co., Ltd. was added to 4 parts of heavy calcium carbonate powder 4 having an average particle diameter of 1.3 μm.
The composition containing 0 parts was melt-kneaded using another two extruders, molded into a sheet at a temperature of 200 ° C. from a die, and laminated on both sides of the longitudinally stretched sheet. Was once cooled to a temperature 20 ° C. higher than room temperature, heated again to a temperature of about 150 ° C., stretched 8 times in the transverse direction using a tenter, and then oven set at a temperature of 160 ° C. After passing through the inside and heat setting, a synthetic paper (thickness 150 μm) having a three-layer structure in which the thickness of the biaxially stretched film of the intermediate layer was 50 μm and the thickness of the uniaxially stretched film of the front and back layers was 25 μm each was obtained. .. Offset printing was performed in the same manner as in Example 1 except that the synthetic paper thus produced was used, and the curl height of the printed matter was measured in the same manner as in Example 1. The results are shown in Table 3.

Comparative Example 3 Printing was performed in the same manner as in Example 3 except that stearyl methacrylate was not applied, and the curl height of the printed matter was measured in the same manner as in Example 1. The results are shown in Table 3.

Examples 4 to 6 Polypropylene-based synthetic paper "YUPO FPG150" (trade name, thickness 150 μm) manufactured by Oji Yuka Synthetic Paper Co., Ltd. was coated with various higher alcohol esters shown in Table 1 Printing was performed in the same manner as in Example 1, and the curl height of the printed matter was measured in the same manner as in Example 1. The results are shown in Table 3.

Examples 7 to 8 Polypropylene-based synthetic paper "YUPO FPG150" (trade name, thickness 150 μm) manufactured by Oji Yuka Synthetic Paper Co., Ltd. was coated with organic acid esters of various higher aliphatic alcohols shown in Table 1. Printing was performed in the same manner as in Example 1 except that electron beam irradiation (5 MRAD) was performed after the work was performed and dried, and the curl height of the printed matter was measured in the same manner as in Example 1. The results are shown in Table 3.

Comparative Example 4 Printing was carried out in the same manner as in Examples 4 to 11 except that the organic acid esters of various higher aliphatic alcohols were not applied, and the curl height of the printed matter was the same as in Example 1. It was measured. The results are shown in Table 3.

Example 9 Stearyl methacrylate was applied to both sides of polypropylene-based synthetic paper "Yupo FPG150" (trade name, thickness 150 μm) manufactured by Oji Yuka Synthetic Paper Co., Ltd., and then calcium carbonate was used as a pigment to form an adhesive. SBR (styrene
Butadiene copolymer rubber) and starch were used to print in the same manner as in Example 1 except that calcium carbonate-containing SBR / starch pigment coating was performed, and the curl height of the printed matter was the same as in Example 1. Was measured. The results are shown in Table 3.

Comparative Example 5 Example 12 was prepared on polypropylene-based synthetic paper “Yupo FPG150” (trade name, thickness 150 μm) manufactured by Oji Yuka Synthetic Paper Co., Ltd., which was not coated with the organic acid ester of higher aliphatic alcohol. After the pigment coating of SBR / starch containing calcium carbonate was performed in the same manner as above, printing was performed in the same manner as in Example 1, and the curl height of the printed matter was measured in the same manner as in Example 1. The results are shown in Table 3.

Comparative Example 6 Printing was carried out in the same manner as in Example 12 except that the organic acid esters of various higher aliphatic alcohols were not applied and the SBR / starch pigment containing calcium carbonate was not applied, and the printed matter was printed. The curl height was measured in the same manner as in Example 1. The results are shown in Table 3.

[0029]

[Table 3]

[0030]

EFFECTS OF THE INVENTION The polyolefin film having excellent offset printability according to the present invention is previously coated with an organic acid ester of a higher aliphatic alcohol, which is a part of the vehicle of the ultraviolet ink or a composition close to the vehicle, and dried. Therefore, even if offset printing is performed and the offset ink is applied to the surface after that, unevenness is not likely to occur on the surface of the printed polyolefin film or synthetic paper, and curl is not likely to occur on the entire film.

[Brief description of drawings]

FIG. 1 is a perspective view showing a method for measuring a curl height of a printed matter according to an embodiment of the present invention.

[Explanation of symbols]

 1 printed matter 2 flat plate h curl height (cm)

Claims (2)

[Claims] 1. A polyolefin film having excellent offset printability, characterized in that an organic acid ester of a higher aliphatic alcohol is coated on one side or both sides of the polyolefin film. 2. The polyolefin film having excellent offset printability according to claim 1, which is subjected to electron beam irradiation or ultraviolet irradiation after applying an organic acid ester of a higher aliphatic alcohol.