JPH0593081A - Polyolefin film with excellent printability - Google Patents

Abstract

(57) [Summary] [Purpose] Even when offset printing is performed using a general-purpose oxidation-polymerization type (dry oil type) offset ink, unevenness may occur on the surface or curl may occur on the entire film. To provide a difficult-to-use polyolefin film. [Structure] A compound selected from higher fatty acids, higher aliphatic alcohols, higher fatty acid esters, higher alcohol acid esters and mineral oils containing a long-chain alkyl group having 8 or more carbon atoms is applied to one or both sides of a polyolefin film. And then uniaxially or biaxially stretched, a polyolefin film having excellent printability.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a uniaxially or biaxially oriented polyolefin having excellent printability, which prevents the film from becoming uneven or curled by the vehicle in the offset ink even when offset printing is performed. Regarding film.

[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 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.

[0007]

[Means for Solving the Problems]

[Summary of the Invention] As a result of intensive studies, the present inventors have found that
A compound containing a long-chain alkyl group having 8 or more carbon atoms, which is a composition of a drying oil or a mineral oil which is a part of a vehicle of an offset ink, or a composition close to that, on a surface of a polyolefin film or a polyolefin-based synthetic paper on which offset printing is to be performed. If it is applied and permeated in advance, then even if offset printing is performed on the surface and offset ink is applied to the surface, unevenness will occur on the surface of the printed polyolefin film or synthetic paper, or the entire film will be curled. The present invention has been completed based on the finding that it is unlikely that occurrence occurs. That is, the polyolefin film having excellent printability according to the present invention has a higher fatty acid, a higher aliphatic alcohol, a higher fatty acid ester, a higher alcohol containing a long-chain alkyl group having 8 or more carbon atoms on one or both sides of the polyolefin film. It is obtained by applying a compound selected from acid ester and mineral oil and then uniaxially or biaxially stretching it. Further, in order to further enhance the effect of the present invention, the uniaxial or biaxial stretching is performed, and then electron beam irradiation or ultraviolet irradiation is further performed.

[Detailed Description of the Invention] [I] Polyolefin Film with Excellent Printability (1) Structure The polyolefin film with excellent printability of the present invention has a wall thickness of 20 to 700 μm, preferably 60 to 200 μm. It has a structure in which a long-chain alkyl group-containing compound having 8 or more carbon atoms is applied to one or both surfaces of a film (including a sheet), and at least a part of the long-chain alkyl group-containing compound is impregnated inside the film. .. Therefore, the long-chain alkyl group-containing compound applied to the surface of the film and the long-chain alkyl group-containing compound impregnated into the film are present. The long-chain alkyl group-containing compound that is not impregnated inside and remains on the surface is preferably cured by electron beam irradiation or ultraviolet irradiation.

(2) Amount ratio The amount of the long-chain alkyl group-containing compound applied to this surface is generally 0.1 to 20 g / in the stretched film.
m ² , preferably 1-3 g / m ² remains on the surface,
Further, a part thereof is impregnated into the inside of the film, and the amount thereof is generally 0.1 to 20% by weight, preferably 1 to 3% by weight in the film. Particularly, the long-chain alkyl group-containing compound capable of exhibiting the effect of the present invention is one that is impregnated into the inside of the film. Quantity is important. By coating the long-chain alkyl group-containing compound before stretching, the amount of the long-chain alkyl group-containing compound that is impregnated into the inside of the film by the heat during stretching increases. Therefore, the effect is even higher.

[II] Method for producing polyolefin film having excellent printability (1) Raw material (a) Polyolefin film As a polyolefin film used as a raw material for the polyolefin film having excellent printability of the present invention,
A film having a wall thickness of 20 to 700 μm obtained by forming a polyolefin resin into a film by various film forming methods, for example, various forming processing methods such as a T-die method, a calendering method, a casting method, and an inflation method (also a sheet is used. Including). 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. A polyolefin film obtained by molding an olefin copolymer or the like obtained by copolymerizing (1.8 to 15% by weight) other comonomer by the above-mentioned various film molding methods, or An opaque or translucent synthetic paper having microvoids inside the film, which is obtained by mixing a small amount of inorganic fine powder into the film and finally stretching it uniaxially or biaxially in the stretching step described below (Japanese Patent Publication No.
6-40794, JP-B-60-36173, JP-B-62-59668, JP-B-63-64310, and JP-A-3-189141). Among these polyolefin films, particularly, inorganic fine powder of 8 to 65 is contained in a polyolefin resin obtained by polymerizing or copolymerizing monomers 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 and stretching the inorganic fine powder-containing polyolefin film containing 10% by weight, preferably 16 to 55% by weight, which is described later, is suitable in terms of adhesion of printing ink. ..

(B) Long-chain alkyl group-containing compound having 8 or more carbon atoms A compound having 8 or more carbon atoms which is used as a raw material of the polyolefin film having excellent printability of the present invention and which is coated and impregnated on the surface of the polyolefin film. The long-chain alkyl group-containing compound has a molecular weight of 140 to 1,300, preferably 140 to 600, a higher fatty acid, a higher aliphatic alcohol, an ester of a higher fatty acid, an acid ester of a higher aliphatic alcohol having 8 or more carbon atoms, Or it is mineral oil. Specific examples thereof are shown below.

Higher fatty acid ester As the higher fatty acid, saturated caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, montanic acid, mericinic acid, etc. Fatty acids, fatty acids having 8 or more carbon atoms such as unsaturated fatty acids such as oleic acid, linoleic acid and linolenic acid (molecular weight 144 to about 34
0) can be mentioned.

Higher Aliphatic Alcohol The above-mentioned higher aliphatic alcohols include capryl alcohol, caprin alcohol, lauryl alcohol, cyristyl alcohol, palmityl alcohol, stearyl alcohol, arachidyl alcohol, behenyl alcohol, lignoceryl alcohol, cellotyl alcohol, montan. Higher aliphatic alcohols having 8 or more carbon atoms (molecular weight 128 to about 31
8) can be mentioned.

Esters of higher fatty acids Examples of higher fatty acid esters include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, melicinic acid. Esters of higher fatty acids such as saturated fatty acids having 8 or more carbon atoms such as unsaturated fatty acids such as oleic acid, linoleic acid and linolenic acid with monofunctional alcohols such as methanol, propanol, butanol and amyl alcohol, Alternatively, ethylene glycol, esters with polyfunctional alcohols such as glycerin, or linseed oil, tung oil, soybean oil, rapeseed oil, castor oil, vegetable oil such as palm oil, fish oil,
Ester compounds such as animal oil such as whale oil (molecular weight 170
~ About 1,300).

Acid of higher aliphatic alcohol having 8 or more carbon atoms
Esters As the above-mentioned acid esters of higher aliphatic alcohols having 8 or more carbon atoms, there are capryl alcohol, caprin alcohol, lauryl alcohol, cyristyl alcohol, palmityl alcohol, stearyl alcohol, arachidyl alcohol, behenyl alcohol, lignoceryl alcohol, cerocyl. Alcohols, saturated alcohols such as montan alcohol, mesosil alcohol, oleyl alcohol, linole alcohol, unsaturated alcohols such as linolel alcohol, alcohols such as higher aliphatic alcohols having 8 or more carbon atoms, and propionic acid acetate, butyric acid, acrylic acid Examples thereof include acid, methacrylic acid, maleic acid, fumaric acid and the like, preferably an ester with an organic acid having 2 to 8 carbon atoms (molecular weight: 172 to about 450).

Mineral Oil As the above-mentioned mineral oil, kerosene, heavy solvent naphtha, which is used as a component of ink, or compounds having a long chain alkyl group such as sewing machine oil, machine oil, liquid paraffin and polyethylene wax (molecular weight: about 450). ~
1300).

(2) Coating Fabric (a) Coating Method The polyolefin film having excellent printability of the present invention is prepared by coating the above-mentioned raw material polyolefin film with the above-mentioned long-chain alkyl group-containing compound having 8 or more carbon atoms. ,
It can be produced by impregnating the long-chain alkyl group-containing compound even inside the polyolefin film by heat during stretching in the stretching step described later. In order to apply the long-chain alkyl group-containing compound to the surface of the unstretched polyolefin film, it is preferable to apply the undiluted solution in the case of a liquid material and the liquid state by heating and heating in the case of a solid material. ..
However, when the long-chain alkyl group-containing compound is solid or has a high viscosity and is difficult to apply, various diluents such as toluene, xylene and mineral spirits can be used. When such a diluent is used, it is preferably dried in a dryer and then moved to the next stretching step.

(B) Application Timing The application timing of the compound having a long-chain alkyl group having 8 or more carbon atoms on the surface of the polyolefin film is as follows.
When a uniaxially stretched film is obtained, it is preferably applied before the uniaxial stretching, and when a biaxially stretched film is obtained, it is preferably applied before longitudinal stretching or before transverse stretching after longitudinal stretching. When applying a long chain alkyl group-containing compound after stretching,
Since a long time is required for permeation after coating, the film immediately after being produced by coating the liquid long-chain alkyl group-containing compound at room temperature feels moist and cannot be put to practical use.
Therefore, a film that can be practically used cannot be obtained unless the coated film is left for a long period of time to allow the coating liquid to penetrate into the inside and to be dried. However, the film produced by coating and stretching the long-chain alkyl group-containing compound before subjecting the film to the stretching step does not feel moist even immediately after the production, and thus is a film that can be sufficiently put to practical use. Furthermore, when applying after stretching, even a liquid coating solution requires a long time for permeation, so it was not suitable for a method of applying a solid long-chain alkyl group-containing compound at room temperature without using a diluent. In the case of coating before stretching, most of the long-chain alkyl group-containing compound can be permeated in the subsequent stretching, so that even a long-chain alkyl group-containing compound that is solid at room temperature can be coated and impregnated.

(C) Coating Means As a means for coating such a long-chain alkyl group-containing compound having 8 or more carbon atoms on the surface of the polyolefin film before stretching, specifically, gravure coating and Meyer bar coating are used. Well-known coating means such as roll coating, blade coating, size press coating and the like can be adopted. In addition to coating, the polyolefin film may be dipped and impregnated in a liquid tank containing a long-chain alkyl group-containing compound. Especially in the production of biaxially stretched film, if applied before stretching,
Compared with the case of applying after stretching, it can be applied with a small-sized and inexpensive coater device that does not take up a lot of space.

(D) Coating amount The coating amount depends on the draw ratio, but in general, the solid content of the long-chain alkyl group-containing compound having 8 or more carbon atoms after stretching is 0.1 to 20 g / m ² , It is preferably in the range of 1 to 3 g / m ² . Further, by coating the long-chain alkyl group-containing compound having 8 or more carbon atoms before the stretching step, the heat of stretching in the subsequent step promotes the penetration of the long-chain alkyl group-containing compound into the interior of the polyolefin film. Therefore, the coating amount can be reduced as compared with the case of coating after stretching.

(3) Elongation (impregnation) (a) Elongation The polyolefin film coated with the above long chain alkyl group-containing compound is further uniaxially stretched or biaxially stretched at a temperature lower than the melting point of the polyolefin resin. An axially stretched polyolefin film or synthetic paper can be obtained. In the present invention, it is important to impregnate the polyolefin film with the long-chain alkyl group-containing compound having 8 or more carbon atoms applied to the surface of the polyolefin film in the stretching step. Is.

(B) Stretching Conditions Therefore, the heating temperature of the polyolefin resin during stretching is generally 3 to 30 ° C., preferably 5 to 25 ° C. lower than the melting point of the polyolefin resin. The stretching at this time is unidirectional or bidirectional, and therefore the number of stretching axes is uniaxial or biaxial. The stretching ratio is generally 1.3 to 15 times, preferably 3.5 to 10 times. By this drawing step, the organic or inorganic fine powder is 8 to 6
By stretching the polyolefin resin film containing 5% by weight, fine voids (voids) are formed on the surface, and the whiteness and opacity of the film are increased. In addition, another resin film is laminated before or after the stretching step, if necessary.

(4) Electron Beam Irradiation or Ultraviolet Irradiation By coating a compound containing a long-chain alkyl group before stretching, a dry-feeling film can be produced immediately after the production as described above. Touch it,
In order to prevent the liquid long-chain alkyl group-containing compound from transferring when it comes into contact with food, electron beam irradiation is performed after stretching, or a photoinitiator is added to the long-chain alkyl group-containing compound in advance and applied. After that, it is preferable to perform ultraviolet irradiation.

(5) Other Additional Treatments Further, pigment coating or the like may be performed on the film to further improve the suitability for offset printing. Pigment Coating The pigment coating can be carried out according to a general coating method for coated paper. Examples of the pigment used for pigment coating include clay, talc, calcium carbonate, magnesium carbonate, aluminum hydroxide, silica, aluminum silicate, calcium silicate, plastic pigment, silica-containing composite latex and the like used for ordinary coated paper. be able to. As the adhesive used at this time, latex such as SBR (styrene-butadiene rubber), MBR (methacryl-butadiene rubber), acrylic emulsion, starch, PVA (polyvinyl alcohol), CMC
(Carboxymethyl cellulose), methyl cellulose and the like can be mentioned.

[III] Offset Printing The thus obtained polyolefin film having excellent offset printing properties of the present invention is subjected to offset printing by adhering the 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.

As the vehicle, synthetic resin, vegetable oil (drying oil), solvent and the like can be mentioned. 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. Examples of the dryness adjusting agent 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. The polyolefin film excellent in printability of the present invention thus obtained is subjected to offset printing, and even if the offset ink is attached to the surface thereof, unevenness occurs on the surface of the printed polyolefin film or the synthetic paper. It is unlikely that the entire film will curl.

[0028]

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. [I] Evaluation method (1) A curl height evaluation film using a 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, has a transfer amount of 1 g / Printing was performed on the entire surface so as to be m ² . And the printed matter is 12c
After being cut into a size of m × 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 The transfer amount was 1 g / m ² 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, as an 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.

[II] Experimental Example 1 Production of Film 85% by weight of polypropylene having a melt index (MI) of 0.8 (melting point 164 ° C.), 5% by weight of high-density polyethylene and 10% calcium carbonate having an average particle size of 1.5 μm. The composition containing 100% by weight was kneaded by an extruder set at 270 ° C., extruded into a sheet, and further cooled by a cooling device to obtain an unstretched sheet. Coating and Stretching Then, linseed oil was coated on this unstretched sheet with a Meyer bar so that the coating amount was 10 g / m ² . And
The sheet was heated again to a temperature of 150 ° C. and then stretched 5 times in the machine direction to obtain a uniaxially stretched film. Printing On this uniaxially stretched film, a dry offset ink commercially available, New Best One Process Ink M (produced by Toka Dye Co., Ltd.), which is commercially available on an offset printing machine, is printed over the entire surface so that the transfer amount is 1 g / m ^2. Was applied. Evaluation The curl height and the occurrence of irregularities of the obtained printing film were evaluated according to the above-described evaluation method. The results are shown in Table 3.
Shown in.

Comparative Example 1 A uniaxially stretched film was obtained and offset printing was performed in the same manner as in Example 1 except that linseed oil was not applied.
The curl height and the occurrence of irregularities of the printed matter were evaluated in the same manner as in Example 1. The results are shown in Table 3.

Example 2 Production of Film 85% by weight of polypropylene having a melt index (MI) of 0.8 (melting point 164 ° C.) was mixed with 5% by weight of high density polyethylene and 10% by weight of calcium carbonate having an average particle size of 1.5 μm. The composition was kneaded by an extruder set at 270 ° C., extruded into a sheet, and further cooled by a cooling device to obtain an unstretched sheet. Coating / Stretching Then, the sheet was heated again to a temperature of 150 ° C. and then stretched 5 times in the machine direction. Liquid paraffin was applied to the sheet stretched in the machine direction so that the coating amount was 20 g / m ² . Then, it is heated again to a temperature of 160 ° C. and stretched 7.5 times in the transverse direction using a tenter,
Annealing treatment was performed at a temperature of 60 ° C., the temperature was cooled to 60 ° C., and the ears were slit to obtain a biaxially stretched film. Printing This biaxially stretched film was coated with a dry offset ink, New Best One Process Ink M (manufactured by Toka Dye Co., Ltd.), which is commercially available in an offset printing machine, over the entire surface so that the transfer amount becomes 1 g / m ^2. Printed. Evaluation The curl height and the occurrence of irregularities of the obtained printing film were evaluated according to the above-described evaluation method. The results are shown in Table 3.
Shown in.

Example 3 Example 3 was repeated except that the liquid paraffin used in Example 2 was replaced with ethyl oleate. The results are shown in Table 3.

Example 4 The film produced in Example 3 was irradiated with an electron beam so as to have 3 MRAD, and then printing was performed in the same manner as in Example 3 to evaluate the obtained printing film. The results are shown in Table 3.

Comparative Example 2 The liquid paraffin used in Example 2 was not applied.
It carried out similarly to. The results are shown in Table 3.

Example 5 Production of Film (1) 81% by weight of polypropylene having a melt index (MI) of 0.8 (melting point of 164 ° C.), 3% by weight of high-density polyethylene and calcium carbonate 16 having an average particle size of 1.5 μm 16
The composition (A) containing 1% by weight was kneaded by an extruder set at 270 ° C., extruded into a sheet, and further cooled by a cooling device to obtain an unstretched sheet. Then, this sheet was heated again to a temperature of 150 ° C. and then stretched 5 times in the machine direction. (2) Polypropylene with MI of 0.4 (melting point 164-116
(7 ° C.) 54% by weight and 46% by weight of calcium carbonate having an average particle size of 1.5 μm were mixed and kneaded in another extruder, and then extruded into a sheet from a die. Was laminated on both sides of the 5-fold stretched film of (1) to obtain a laminated film having a three-layer structure. Coating / Stretching 1 layer of ink solvent 5sol (manufactured by Nippon Oil Co., Ltd.), which is a solvent for printing ink, is applied on the three-layer laminated film.
It was applied so as to be 5 g / m ² . Then again about 17
Heated to a temperature of 5 ° C, stretched 7.5 times in the transverse direction using a tenter, annealed at a temperature of 165 ° C,
Cooled to a temperature of 60 ° C, slit the ears, and have a three-layer structure (uniaxially stretched / biaxially stretched / uniaxially stretched) with a wall thickness of 80 μm.
A film of (B / A / B = 20 μm / 40 μm / 20 μm) was obtained. Printing / Evaluation The same printing and evaluation as in Example 1 were performed. The results are shown in Table 3.

Example 6 Example 6 was repeated except that stearyl methacrylate was applied instead of the ink solvent 5sol (manufactured by Nippon Oil Co., Ltd.). The results are shown in Table 3.

Example 7 The film produced in Example 6 was irradiated with an electron beam (irradiation amount: 3 MRAD), then printing was carried out in the same manner as in Example 6, and the obtained printed film was evaluated. The results are shown in Table 3.

Examples 8 to 10 The same procedure as in Example 5 was carried out except that boil oil, oleic acid or oleyl alcohol was applied instead of the ink solvent 5sol (manufactured by Nippon Oil Co., Ltd.). The results are shown in Table 3.

Comparative Example 3 The procedure of Example 5 was repeated except that the ink solvent 5sol (manufactured by Nippon Oil Co., Ltd.) was not applied. The results are shown in Table 3.

Comparative Example 4 Polypropylene-based synthetic paper "YUPO FPG150" (trade name, manufactured by Oji Yuka Synthetic Paper Co., Ltd.) to which the ink solvent 5sol (manufactured by Nippon Oil Co., Ltd.) in Example 5 was not applied.
The same procedure as in Example 5 was carried out except that a thickness of 150 μm) was used. The results are shown in Table 3.

[0041]

[Table 3]

[0042]

EFFECTS OF THE INVENTION The polyolefin film having excellent printability according to the present invention contains a long-chain alkyl group having 8 or more carbon atoms, which has a composition similar to that of a drying oil or a mineral oil which is a part of the vehicle of the offset ink. Since the compound is applied and impregnated, even if offset printing is applied to the surface after that, unevenness will occur on the surface of the printed polyolefin film or synthetic paper, or curl will occur on the entire film Is unlikely to occur. Compared to the case where a long chain alkyl group-containing compound is applied after stretching, it does not require a long time for impregnation after application, so a film does not feel moist even immediately after production, and it can withstand practical use in a short time. A film is obtained.
In addition, since the long chain alkyl group-containing compound is applied before the stretching step, the heat of the stretching step in the subsequent step promotes the penetration of the long chain alkyl group-containing compound into the interior of the polyolefin film, thus increasing the coating amount. Compounds containing long-chain alkyl groups that can be reduced and are solid at room temperature can also be used. Further, the biaxially stretched film can be coated with an inexpensive small coater device that does not occupy a space as compared with the method of coating after stretching.

[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)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // B29K 23:00 B29L 9:00 4F

Claims (2)

[Claims] 1. A compound selected from a higher fatty acid, a higher aliphatic alcohol, a higher fatty acid ester, a higher alcohol acid ester and a mineral oil containing a long-chain alkyl group having 8 or more carbon atoms on one or both sides of a polyolefin film. A polyolefin film having excellent printability, characterized in that it is uniaxially or biaxially stretched after being coated with. 2. The polyolefin film having excellent printability according to claim 1, which is further irradiated with an electron beam or an ultraviolet ray after being uniaxially or biaxially stretched.