JP2667244B2 - Manufacturing method of film sheet for printing - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for producing a printing sheet having the same high gloss as cast-coated paper, and particularly to a printing method having good dimensional stability, printing smoothness, and ink drying property. The present invention relates to a method for efficiently producing a printing film sheet having excellent water resistance.

[Conventional technology]

As a method for producing a high gloss coated paper for printing called cast coated paper, a wet cast method in which a wet coated layer is pressed against a heated cast drum surface having a mirror surface to perform gloss finish,
The wet coating layer is dried once, then plasticized by rewet and pressed against the mirror-surfaced heated cast drum surface. The wet coating layer is formed into a gel state and the wet coated layer is pressed against the mirrored heated cast drum surface. Methods such as a gelling casting method are known.

In any of the methods for producing such a cast-coated paper, a coating layer containing a pigment and an adhesive as a main component is formed on a paper support, and the coated layer is pressed into a heated cast drum surface having a mirror surface in a wet state to be in a plastic state. This is a method in which a mirror surface is copied onto a certain coating layer to finish it as a coated paper having a smooth and high gloss. Moisture in the wet coating layer cannot evaporate to the finished surface side because the coating layer is in close contact with the heated cast drum surface. Must be done.

For this reason, the base paper is required not only to have good air permeability as described above, but also to have good dimensional stability so that curling, waving, and the like do not occur due to moisture. However, wood cellulose, which is usually used as base paper,
There is a limit even if treated with a sizing agent, a waterproofing agent, a repellent, etc.
Some degree of paper expansion and contraction is inevitable.

In order to improve this, inorganic fibers such as glass fiber, asbestos, aluminosilicate fiber, and carbon fiber, and organic paper such as polypropylene, polyethylene, nanlon, acrylic fiber, aramid fiber, phenolic fiber, fluorine-based fiber, and synthetic pulp are used to improve this. The fibers may be mixed with wood pulp or may be used alone in a sheet form. However, when these fibers are formed into a sheet, their smoothness is inferior. Therefore, when finished into cast coated paper, the smoothness of the surface is noticeably deteriorated.

It is also conceivable to perform a cast coat finish on the film to obtain a printing sheet with high smoothness and high gloss, but a so-called drum in which a normal film has poor air permeability and a coating layer is picked on the cast drum surface. A pick occurs,
It was difficult to obtain a continuous cast coat layer.

[Problems to be solved by the invention]

In view of this situation, the present inventors have conducted intensive studies on the elimination of the above-described disadvantages when providing a cast coat layer on a film support, and as a result, the use of a specific film of the support has made it operable. It was found that a printing film sheet having high smoothness, high gloss and excellent printability was obtained without any difference from the case of a paper support.

[Means for solving the problem]

According to the present invention, a coating layer containing a pigment and an adhesive as a main component is provided on a support, and while the coating layer is in a wet state, the coating layer is pressed against a heated casting drum having a mirror surface and dried to obtain a high gloss finish. In the method for producing a printing film sheet, a microporous synthetic resin film sheet is used for the support, which is a method for producing a printing film sheet.

[Action]

The microporous synthetic resin film as a support used in the present invention is polyethylene, polypropylene, polybutene, polystyrene, polymethylpentel, ethylene
Polypropylene resin-based polymers such as propylene copolymers, ethylene / butylene copolymers, propylene / butene copolymers, polyvinylidene fluoride, fluororesin polymers such as polytetrafluoroethylene, polyurethanes, phenolic polyethers, cellulose acetate, It is produced by stretching a film of a simple substance or a mixture of an acrylonitrile-based polymer, an amide-based resin, a polyester-based resin or the like in a uniaxial or biaxial direction. In addition, inorganic fillers such as calcium carbonate, kaolin, talc, titanium oxide, silica, diatomaceous earth, and zinc oxide, 6-nylon, 6,6-
Polyamide such as nylon: Fluorine resin such as polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer: Polyimide: Silicone resin: Phenol resin: Benzoguanamine resin: Or styrene, acrylic acid, methacrylic acid, acrylic It is also useful to use one or more of synthetic resin particles such as a copolymer of methyl acrylate, methyl methacrylate and the like with a crosslinking agent such as divinylbenzene.

At this time, the porous film is directly obtained by stretching, or in the porous film obtained by stretching, the inorganic filler in the porous film is eluted with an acid or the like to further increase the permeability, and the porous film is formed. Is also useful.

The degree of stretching, it is possible to adjust the pore size of the microporous film by the particle size of the filler, but as a support for the cast coat of the present invention, the filler is 20 to 100 parts by weight of the resin. Containing 300 parts by weight, maximum pore size of 10μm or less, air permeability (TAPPI T 536 hm-85 (HP method)) of 300s
It is desirable for it to be less than ec / 10cc in order to obtain high smoothness and high strength. At this time, by adjusting the dynamic wetting value of the surface of the microporous film in the range of -0.30 to 0.10 g, an excellent function as a printing film can be further provided. Here, the dynamic wetting value is a value obtained by temporally measuring the wettability (adhesive force) of base paper with water using a dynamic wettability tester (WET-3000 / manufactured by Resca).

That is, the test paper pieces (2 × 5 cm) after the undercoat coating layers were provided on both sides of the base paper using the above-mentioned tester were immersed in water at a depth of 12 mm at a speed of 16 mm / sec for 10 seconds. It measures the magnitude (adhesive force) of the actual wetting. The value of the wetting, that is, the dynamic wetting value, indicates that the smaller the value, the more difficult it is to wet, and the larger the value, the more easily the wetting. As a result of further study on the wetting value, the wetting value two seconds after immersion in water was measured as the temporal wetting value measured by this tester. It was found that there was a great correlation with the above. Therefore, the dynamic wetting value referred to in the present invention refers to the wetting value two seconds after immersion in water.

In the present invention, the coating composition used for forming the coating film is mainly composed of a pigment and an adhesive, similarly to the conventional composition for cast coated paper.

As the pigment, for example, at least one kind of ordinary coated paper pigments such as clay, kaolin, aluminum hydroxide, calcium carbonate, titanium dioxide, barium sulfate, zinc oxide, satin white, and plastic pigment are appropriately selected and used. Is done.

Examples of the adhesive include proteins such as casein, soybean protein, and synthetic protein, conjugated diene polymer latex such as styrene / butadiene copolymer, polymer or copolymer of acrylic acid ester and / or methacrylic acid ester, and the like. Acrylic copolymer latex, vinyl copolymer latex such as ethylene-vinyl acetate copolymer, or alkali-soluble or non-alkali resin obtained by modifying these various polymer latexes with a monomer containing a functional group such as a carboxyl group. Soluble polymer latex, polyvinyl alcohol, synthetic resin adhesives such as olefin / maleic anhydride resins, melamine resins, starches such as positive starch and oxidized starch, cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, etc. One or more adhesives for coated paper may be selected and used as appropriate. It is.

In general, the amount of the adhesive used is 5 to 50 parts by weight, more preferably 10 to 30 parts by weight, based on 100 parts by weight of the pigment.

In the coating composition, various auxiliaries such as an antifoaming agent, a coloring agent, a release agent, and a flow modifier are appropriately compounded as necessary. As an auxiliary for promoting the conversion, for example, a salt of a polyvalent metal such as zinc, aluminum, magnesium, calcium and barium is added in an amount of about 0.5 to 10 parts by weight based on 100 parts by weight of the pigment.

The coating apparatus for the coating composition is, for example, a blade coater, an air knife coater, or the like used in the production of general coated paper.
A roll coater, reverse roll coater, bar coater, curtain coater, die slot coater, gravure coater, size press coater and the like can be used.

The solid content concentration of the coating composition is generally adjusted in the range of about 35 to 70% by weight, but is preferably in the range of 40 to 65% by weight in consideration of operability.

The coating amount of the coating composition on the microporous film is generally about 1 to 40 g / m ² by dry weight (after the coating layer is once formed on a mirror-finished heated casting drum surface, The same applies to the case where a certain microporous synthetic resin film sheet is pressed and dried), but the resulting cast coated paper has a quality of 2 to 35 g in terms of quality such as smoothness and glossiness, and the effect of improving the cast coating speed. It is desirable to adjust in the range of about / m ² . The present invention is also directed to a method for producing a film sheet for printing by forming a coating layer on a heated cast drum surface having a mirror surface once and then pressing and drying a microporous synthetic resin film sheet as a support. However, also in the case of this method, the coating layer is the same as the case described above. In this case, the coating amount can be easily controlled by, for example, a curtain coater or a die slot coater.

The rewetting liquid in the rewet casting method includes, for example, about 0.01 to 3% by weight of a release agent such as water, polyethylene emulsion, fatty acid soap, calcium stearate, microcrystal wax, surfactant, and funnel oil. An aqueous solution or emulsion containing a certain amount is used.

Thus, the present invention makes it possible to produce a printing film sheet having excellent dimensional stability and excellent printing smoothness, ink drying properties, and water resistance.

Examples Hereinafter, examples of the present invention will be described, but it goes without saying that the present invention is not limited to these examples. In the examples, parts and% mean parts by weight and% by weight.

Examples 1 to 11, Comparative Examples 1 and 2, 60 parts of kaolin, 40 parts of soft calcium carbonate, 80 parts of 15% aqueous solution of casein, 12 parts of acrylic acid / butadiene / methyl methacrylate (ratio 2/33/65) copolymer latex ( Solid content), tributyl phosphate 0.5 as antifoaming agent
Parts, and 1.0 parts of ammonium stearate as a release agent, a coating liquid having a solid content concentration of 45% was prepared.

Using the obtained coating liquid, wet casting was performed using the apparatus shown in FIG. That is, the coating liquid was applied to the surface of the support (1) shown in Table 1 using the coating device (2) at a dry weight of 15 g / m ²
Then, it was pressed against a cast drum (4) having a diameter of 3600 mm and a surface temperature of 90 ° C. by a press roll (3) having a diameter of 200 mm, dried and peeled off to obtain a film sheet for printing (5). Table 1 shows the quality of the obtained printing film sheet.

Examples 12 to 17, Comparative Examples 3 and 4, 70 parts of kaolin, 30 parts of soft calcium carbonate, and 0.5 parts of sodium polyacrylate were dispersed in water using a Cores disperser to prepare a pigment slurry having a solid content of 60%. did. 0.5 parts of tributyl phosphate as an antifoaming agent, 1.0 parts of ammonium stearate as a release agent, 10 parts of casein water-soluble (solid content) dissolved using ammonia as an adhesive, and acrylic acid / butadiene / methyl methacrylate ( 2/33/65) 18 parts (solid content) of copolymerized latex were added, and 3 parts (solid content) of an aqueous solution of ZnSO4 and water were further added to prepare a coating liquid having a solid content of 45%.

Using the obtained coating liquid, the above coating liquid was coated on a support (6) shown in FIG. 4 using a coating apparatus (7) so that the dry weight was 20 g / m ² , It dried with the air floating dryer (8).

Next, a press roll (9) with a diameter of 750 mm and a diameter of 1500 m
Press nip (1) formed with m cast drum (10)
After passing through 1), the surface of the coating layer is rewound with a rewet liquid (0.5%) composed of polyethylene emulsion supplied from the nozzle (12), and then the cast drum (10) having a surface temperature of 100 ° C. After being pressed and dried, it was peeled off to obtain a printing film sheet (14). Table 2 shows the quality of the obtained film sheet for printing.

Examples 18 to 20, Comparative Example 5 70 parts of kaolin, 20 parts of soft calcium carbonate, 10 parts of aluminum hydroxide, 0.5 sodium polyacrylate as a dispersant
And 0.5 parts of sodium pyrophosphate were dispersed in water using a Cores disperser to prepare a pigment slurry having a solid content of 70%. 0.5 part of tributyl phosphate as an antifoaming agent and 1.0 part of ammonium stearate as a releasing agent are added to the slurry.
Then, 13 parts (solid content) of casein water-soluble and 11 parts (solid content) of styrene-butadiene copolymer latex dissolved in aqueous ammonia as an adhesive and water were added to obtain a coating liquid having a solid content concentration of 50%.

Using the obtained coating liquid, gel casting was carried out using an apparatus shown in FIG. That is, the surface of the support (15) shown in Table 3 was coated using a coating device (16) so as to have a dry weight of 10 g / m ^2, and then 0.5% calcium formate and 0.5% ammonium stearate. The coated layer was gelled by contact with an aqueous solution (17). Then, it was pressed against a cast drum (19) having a surface temperature of 92 ° C. and a diameter of 3000 mm by a press roll (18) having a diameter of 800 mm, dried, and peeled to obtain a film sheet for printing (21). Table 3 shows the quality of the obtained film sheet for printing.

[Quality evaluation method]

 Gloss: The larger the (%) value measured according to the JIS P 8142 method, the better the gloss. The smoothness: visually evaluated. Evaluated by observation ◎ …… Not observed ○ …… Not observed Surface strength: Performed 5 times overprinting using Toka dye test ink using RI printability tester (Meiji Seisakusho). The picking state of the printed surface was observed.

◎… Not observed ○ …… Not observed Continuous productivity ◎… Continuous production possible without contamination of the metal drum ○ …… Continuous production possible with slight contamination of the metal drum × …… Dirt on the metal drum [Effect] As is clear from the examples of the present invention, by using a microporous synthetic resin film sheet for the support, it is possible to obtain a printing film sheet excellent in continuous operability and quality. It has become possible.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a case where the present invention is implemented by a wet casting method. FIG. 2 is an explanatory view showing a case where the present invention is carried out by a re-wet casting method. FIG. 3 is an explanatory view showing a case where the present invention is implemented by a re-wet casting method. 1 ... Support, 2 ... Coating device 3 ... Press roll, 4 ... Cast drum 5 ... Printing film sheet 6 ... Support (film) 7 ... Air knife coater 8 ... Air floating dryer 9 …… Press roll 10 …… Cast drum 11 …… Press nip 12 …… Nozzle 13 …… Take off roll 14 …… Printing film sheet 15 …… Support (film) 16 …… Roll coater 17 …… Calcium formate aqueous solution 18 Press roll 19 Cast drum 20 Take-off roll 21 Printing film sheet

Claims (4)

(57) [Claims] 1. A coating layer comprising a pigment and an adhesive as a main component is provided on a support, and while the coating layer is in a wet state, it is pressed against a heated cast drum having a mirror surface and dried to obtain a high gloss finish. The method for producing a printing film sheet, wherein a microporous synthetic resin film sheet is used as a support in the method for producing a printing sheet. 2. The printing film according to claim 1, wherein the air permeability (TAPPI T 536 hm-85 (HP method)) of the microporous synthetic resin film sheet is 300 sec / 10 cc or less. Sheet manufacturing method. 3. The method for producing a printing film sheet according to claim 1, wherein the dynamic wetting value of the microporous synthetic resin film sheet is from -0.30 to 0.10 g. 4. A microporous synthetic resin film sheet comprising 20 to 300 parts by weight of a filler based on 100 parts by weight of a polyolefin resin.
A method for producing the printing film sheet according to the above.