JPH09302207A - Transparent film for liquid jet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a biodegradable OHP film which is excellent in light transmittance and marring resistance and to which an ink adheres well without causing nonuniformity in printing, such as pinholes, even when printing is made on the surface independent of the type of a printing press by using a lactic acid polymer, an etylene/vinyl acetate copolymer and a lubricant as the principal constituents. SOLUTION: This film contains as the principal constituents a lactic acid polymer (A), an ethylene/vinyl acetate copolymer (B) and a lubricant (C). Examples of component A used include a polylactic acid preferably having a weight-average molecular weight of 100,000 to 300,000 and a lactic acid/ hydroxycarboxylic acid copolymer consisting of 80-20wt.% lactic acid units and 20-80wt.% hydroxycarboxylic acid (e.g. glycolic acid) units and preferably having a molecular weight of 100,000 to 200,000. The component B preferably comprises one having an ethylene content of 30-90wt.% and a vinyl acetate content of 30-90wt.%, and it is used in an amount of 5-70 pts.wt. based on 100 pts.wt. component A. The lubricant C used comprises, e.g. a fatty acid ester, which is blended in an amount of 0-0.5wt.% based on the component A.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a transparent film for liquid jet recording, which is a film composed of a composition containing a lactic acid-based polymer as a main component and has excellent transparency.

[0002]

2. Description of the Related Art A transparent film for liquid jet recording, a so-called absorption type OHP film, is a film which is formed by jetting a water-based ink on the film surface as represented by an ink jet printer. Such an OHP film is required to have a high ink absorption speed, the diameter of the inkjet after recording does not become larger than necessary due to diffusion, the transparency of the film is high, and the durability is high. As a base film for OHP films, polyethylene terephthalate (PET) has been generally used because of its transparency, strength and economy. However, since this base film does not absorb ink,
The printability is supplemented by providing an ink absorbing layer having a high affinity for the ink on the base material. Such a film is poor in light transmittance and transfer to a screen, and after use, it is cut as a waste by a shredder or the like.

Such an ink-printable OHP film has become possible to more easily produce an image by a personal computer which has been popularized in recent years, and its spread has been accelerated due to the technical progress and cost reduction of inkjet printers. Has been done. Even today, for presentation O
The HP film is used in the millions of sheets / month in Japan, and the usage amount is expected to increase further. Therefore, the disposal amount of the OHP film after the use is increasing.

[0004]

In view of the above, the film base material such as PET which has been conventionally used is frequently used, but is buried as dirt after use in the soil,
The actual situation is that it is not permanently decomposed, remains in the soil, and is not recovered and used. The present invention provides a transparent film for liquid jet recording, which uses a biodegradable polymer, does not impair transparency, strength and printability, and has biodegradability in a natural environment when discarded. is there.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that lactic acid-based polymers,
A biodegradable liquid jet recording film (O) having excellent transparency, strength and printability is obtained by using a thermoplastic resin composition containing a composition containing a vinyl acetate copolymer and a lubricant as main components.
HP film) could be obtained.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail. In the present invention, a lactic acid-based polymer is used as the biodegradable polymer. Examples of the lactic acid-based polymer include polylactic acid and lactic acid-hydroxycarboxylic acid copolymer. To be This lactic acid-based polymer can be used alone or as a mixture.

The polylactic acid used in the present invention includes L-lactic acid and D-lactic acid.
-It can be obtained by dehydration condensation of lactic acid or a mixture thereof, and preferably by ring-opening polymerization of lactide which is a cyclic dimer of lactic acid. The lactide includes L-lactide which is a cyclic dimer of L-lactic acid, D-lactide which is a cyclic dimer of D-lactic acid, DL-lactide which is a cyclic dimer of D-lactic acid and L-lactic acid, and the like. Among them, one kind or two or more kinds can be used. Ring-opening polymerization of lactide is preferable because polymerization of lactide is easy and a product with a high degree of polymerization is easily obtained. The weight average molecular weight of the polylactic acid used in the present invention is not particularly limited, but is usually 30,000 to 1,000,000, and preferably 100,000 to 300,000. Examples of commercially available polylactic acid include ECOPLA (manufactured by Cargill) and Lacty (manufactured by Shimadzu Corporation).

The lactic acid-hydroxycarboxylic acid copolymer is a copolymer containing 80 to 20% by weight of lactic acid units and 20 to 80% by weight of hydroxycarboxylic acid units. The lactic acid is preferably L-lactic acid, D-lactic acid, or lactic acid obtained by dehydration condensation of a mixture thereof.
Examples of the hydroxycarboxylic acid include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid and 6-hydroxycaproic acid. The molecular weight is preferably 100,000 to 200,000. If the molecular weight is less than 100,000, sufficient breaking strength cannot be obtained, and if it exceeds 200,000, the breaking strength is lowered.

The ethylene-vinyl acetate polymer (hereinafter referred to as EVA) used in the present invention has an ethylene content of 1
Those having 0 to 70% by weight and a vinyl acetate content of 30 to 90% by weight are used, but those having an ethylene content of 20 to 40% by weight and a vinyl acetate content of 60 to 80% by weight are preferable. When the vinyl acetate content is less than 30% by weight, the elongation at break becomes small, and when the vinyl acetate content exceeds 90% by weight, the Izod impact value becomes small.
EVA preferably has a molecular weight of 50,000 to 500,000 and a molecular weight of 5
If it is less than 10,000, the elongation at break becomes small, and if it exceeds 500,000, the breaking strength becomes low. The amount added is EVA
When added, EVA is 5 to 70 parts by weight, preferably 20 to 100 parts by weight, based on 100 parts by weight of the lactic acid-based polymer.
50 parts by weight. When EVA is less than 5 parts by weight, sufficient breaking elongation cannot be obtained, and when it exceeds 70 parts by weight, transparency and strength are deteriorated. Commercially available EVA includes Ebaslen 250, 310P, 450P (manufactured by Dainippon Ink and Chemicals),
Sorex BH, CH, DM (manufactured by Nippon Gosei Co., Ltd.) and the like can be mentioned.

As the lubricant used in the present invention, those generally used can be used, but fatty acid esters,
Hydrocarbon resin, paraffin, higher fatty acid, oxyfatty acid, fatty acid amide, alkylenebis fatty acid amide, aliphatic ketone, fatty acid lower alcohol ester, fatty acid polyhydric alcohol ester, fatty acid polyglycol ester,
Metal soap and a mixture thereof are used. Examples of commercially available lubricants include Riquester EW-100 (fatty acid ester manufactured by Riken Vitamin), Hoechst wax OP (fatty acid Ca / fatty acid ester mixture manufactured by Hoechst), and the like. When these lubricants are added, they are used in the range of 0.05 to 5 parts by weight with respect to 100 parts by weight of the lactic acid polymer. If the amount is less than 0.05 parts by weight, the effect of releasability is insufficient, and if the amount exceeds 5 parts by weight, there is a problem in the coating property of the coating agent exuding from the resin.

In addition to the above composition, an inorganic filler may be used in combination to prevent blocking between films. Examples of the inorganic filler include silica, talc, calcium carbonate, clay, alumina and the like, with silica, talc and calcium carbonate being preferred. The inorganic filler used in the present invention preferably has an average particle size in the range of 1 to 5 μm. When the average particle size is less than 1 μm, a sufficient blocking preventing effect cannot be obtained. Further, if the average particle size exceeds 5 μm, the roughness of the film surface obtained by molding becomes large, and when printing on the film surface, printing unevenness such as pinholes may occur, which is not preferable. The amount of these inorganic fillers added is 0 with respect to the lactic acid-based polymer.
It is preferably from 0.5 to 0.5% by weight, and when it exceeds 0.5% by weight, the transparency of the film is deteriorated.

If desired, one or more heat stabilizers, plasticizers and modified silicones may be contained.

The film base material of the present invention can be formed into a film by a method such as an injection molding method, an extrusion molding method or a cast molding method. Generally, the T-die extrusion molding method is often used, and E is applied to a roll heated to 120 to 160 ° C.
After adding VA and a lubricant all at once, a lactic acid polymer is added and kneaded to form a sheet. Subsequently, the obtained sheet is pelletized by using a pelletizer or the like. The pellets of the polymer were inserted into the extruder from the hopper and the inlet temperature was adjusted to 10
It is melted at 0 to 140 ° C. to form a thin film, so that it is obtained by allowing the T-die outlet temperature to be 160 to 190 ° C. through a T-die mold, flowing out into a film, and cooling. . Set the gap between the mold outlets to 50
By setting the thickness to 600 μm, a film having an appropriate thickness can be prepared, and a film particularly useful as an OHP film can be obtained. The film substrate of the present invention is usually 0.01
˜1 mm, preferably 0.08 to 0.15 mm.

The light transmittance (JIS K 7105) of a film containing as a main component a composition containing a lactic acid-based polymer used as a base material for a transparent film for liquid jet recording of the present invention.
Is 90 for light with a wavelength of 400 to 800 nm.
% Or more is preferable. If it is less than 90%, the projected image will be dark and unclear when projected.

The film substrate of the present invention is desirably coated with a water-absorbing coating material. Examples of the coating material include gelatin, casein, starch, sodium alginate, carboxymethyl cellulose, cationized starch, hydroxyethyl cellulose, polyvinyl acetate, polyvinyl alcohol and the like. If necessary, an inorganic filler can be added to the coating material, and examples of the filler include silica, alumina, aluminum silicate, magnesium silicate, basic magnesium carbonate, talc, clay, hydrotalcide, Inorganic pigments such as calcium carbonate, titanium oxide, zinc oxide and the like can be mentioned. Further, various additives such as a dispersant, a fluorescent dye, a pH adjusting agent, an antistatic agent, an antifoaming agent, a lubricant, and an antiseptic agent are added in order to further improve the recording characteristics as an OHP film, or storage stability and productivity. It can also be added.
As described above, the coating material can be uniformly dispersed in a solvent such as water, and can be applied by a usual coating method such as a gravure coater or a die coater. The thickness of the coating material is preferably 5 to 35 μm.

[0016]

EXAMPLES The present invention will be specifically described below with reference to Examples 1 to 5 and comparative examples, but the present invention is not limited to the following examples.

Examples 1 to 5 The film base material was a 6-inch roll (No.
86-308 type) is heated to 140 ° C./10 minutes, Ebaslen 450P (EVA) and EW-100 (dipentaerythritol stearate) shown in Table 1 are added all at once, and after winding around a roll, Eco-PLA (lactic acid polymer) ) Was gradually added and uniformly kneaded to obtain a roll sheet having a thickness of 2 mm. Pelletize the sheet (GHP manufactured by Tomoo Iron Works Co., Ltd.
Mold) is used to form pellets, and the obtained pellets are used as a raw material in an extruder having a diameter of 50 mm, an inlet temperature of 120 ° C., an outlet temperature of 180 ° C., a screw rotation speed of 30 rpm, and a screw CR1. Under these molding conditions, a film having a length of 29 cm, a width of 21 cm, and a thickness of 100 μm was extrusion-molded.

Further, a coating solution having a solid content of about 20% and having the following composition a was applied onto the obtained film substrate by gravure coating so that the film thickness when dried was 10 μm, and liquid jet recording was transparent. I got a film.

Composition a Colloidal silica (Nissan Chemical Co., Ltd.) 0-40 Particle size 4 nm 70 parts Poval (Shin-Etsu Chemical C-17 (solid content 10%)) 30 parts and water

The obtained transparent film was actually printed with an ink jet printer (BJC-410J manufactured by Canon Inc.), and the film after printing was evaluated for scratch resistance, light transmittance, and degradability in soil.

Light transmittance: Measured according to JIS K 7105. More than 90% ○ Less than 90% ×

Scratch resistance: The appearance of scratches on the film surface after printing was visually observed. Almost no scratches ○ (5 or less / mm ² ) Slightly scratched △ (5 to 20 or less / mm ² ) Many scratches × (20 or more / mm ² )

Biodegradability: OHP is shredded,
After cutting into fine pieces, in the soil with a depth of 10 cm (temperature 10 to 25
C.) and digged out after 0, 3, 6, and 12 months, and the degree of decomposition was observed. Disassembled and not retaining shape ○ Slightly retaining shape △ Retaining shape ×

In addition to the above measurement, a transparent film obtained by an ink jet printer (BJC manufactured by Canon Inc.)
-410J) was used to print a 1 cm square on the film, and a sample was drawn with a cutter so that the gap feeling was 1 mm and the number of squares was 100, and the ink adhesion of the film was measured.

Ink adhesion: In accordance with JIS K 5400 (cross-cut method), the adhesion state of the ink adhering to the film was measured with a cellophane adhesive tape using the above sample. The measurement location is the number of squares of ink adhered to the film after tape peeling.

Comparative Example Using OHP Mach Jet Color for Epson Inkjet Color (MJ-OHP-S1N) in which a PET film was used as a film substrate, the same physical properties as those of the examples were evaluated.

[0027]

[Table 1]

[0028]

As is apparent from Table 1, regardless of the printing model, it has excellent light transmission and scratch resistance, and has good ink adhesion without causing printing unevenness such as pinholes when printed on the film surface. An OHP film having biodegradability is obtained.

Claims (4)

[Claims] 1. A transparent film for liquid jet recording containing a composition containing a lactic acid-based polymer as a main component. 2. A transparent film for liquid jet recording comprising a composition containing a lactic acid-based polymer and an ethylene-vinyl acetate copolymer as a main component. 3. A transparent film for liquid jet recording comprising a composition containing a lactic acid polymer, an ethylene-vinyl acetate copolymer and a lubricant as a main component. 4. The transparent film for liquid jet recording according to claim 1, wherein gelatin, casein, starch, sodium alginate, carboxymethyl cellulose, cationized starch, hydroxyethyl cellulose, polyvinyl acetate,
A transparent film for liquid jet recording coated with a coating material selected from polyvinyl alcohol.