JPS645825B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wet paper paper printing method for clearly printing figures on wet paper paper containing a large amount of water immediately after forming a paper layer in a papermaking process.

Long-roll paper that is punched in a fixed position, such as securities paper, requires a mark to indicate the cutting position when automatically cutting sheets. This mark must be created while the wet paper is in the papermaking process to avoid the effects of paper expansion and contraction in the drying section. Previously, the diameter was approximately 2mm
Register holes were previously inserted in the middle of the papermaking process, but in order to further improve cutting accuracy, a mark with a clearer shape than the holes was printed using a letterpress method at a fixed position relative to the perforated pattern on the wet paper during the papermaking process. We invented a method to do this.

There has been no practical example of printing on wet paper, and in this case, the most difficult problem that hindered this was the occurrence of paper peeling. In other words, when the ink on the printing plate comes into contact with a wet paper that has formed a paper layer but has not yet had sufficient fiber bonding, the fibers of the wet paper are stripped onto the printing plate by the viscosity of the ink, causing the ink to adhere to the wet paper. Also, the paper fibers tend to stick to the plate side. This tendency increases as printing progresses even if the ink viscosity is considerably lowered, so conventional letterpress printing
Inks such as those used in lithographic and intaglio printing cannot be used. Furthermore, even low-viscosity inks such as evaporative inks for gravure printing begin to evaporate and permeate when they come into contact with paper from the printing plate, resulting in increased viscosity and paper peeling. Therefore, even if we take up this problem alone, we can see that considerable ingenuity is required in terms of ink composition.

The second problem is the transferability of the ink. Unlike dry paper, the wet paper layer, which is composed of a considerable amount of water and fibers, has poor ink absorption properties, so it forms an even ink film on its surface. It is extremely difficult to put it on.

Furthermore, the third problem is ink drying.If the ink dries within a short time before the wet paper enters the drying section after printing, and if the ink drying film does not have heat resistance, the blanket or drying tube will not dry. Ink adheres to the surface and contaminates subsequent paper.

The results of trials using various known inks for wet paper printing are as follows, and none of them could be put to practical use.

Typical oxidative polymerization drying inks that use oil-based vehicles tend to peel due to their viscosity.
In addition, ink is difficult to transfer to wet paper due to the repulsion of water and oil, and drying is too slow, making it completely unsuitable.

Penetration drying type for office use (for stamps and fountain pens)
Ink is extremely slow to dry and has poor heat resistance, making it unsuitable.

Evaporative inks that combine low-boiling solvents with resins and colorants transfer onto wet paper, but commercially available oil-based and water-based felt pen inks dry slowly and lack heat resistance for this purpose. Furthermore, evaporative drying inks that use low-boiling point solvents such as acetone, benzene, and ethyl alcohol dry quickly, but are also prone to paper peeling.
In addition, the ink was too volatile and unstable, making printing difficult.

Steam set ink is used for printing on corrugated boards, etc., and is generally made by dissolving water-insoluble highly oxidized rosin-modified maleic acid resin in a water-compatible glycol such as diethylene glycol as a vehicle, and then releasing water vapor after printing. This method dries the ink in a short time by spraying it on the printed material to dilute the water-compatible solvent with water and precipitating the resin component. In wet paper printing using this method,
There was a tendency for the solvent to diffuse into the water at the same time as printing without spraying water vapor after printing, and for water-insoluble resin to precipitate on the paper, causing the ink to dry. However, because the ink begins to dry the moment it comes into contact with paper, it had the most severe paper peeling tendency of all the inks tested, and its ink transfer properties were insufficient, making it unsuitable for practical use as it was.

Therefore, in this invention, a vehicle that combines a glycol solvent and a resin, whose drying mechanism is relatively suitable for wet paper printing, is used as an ink component.
To help prevent paper peeling, the ink viscosity was extremely reduced by using 70 to 95% solvent, which is significantly higher than in general inks. Furthermore, in order to uniformly transfer the ink onto the wet paper, we stopped using diethylene glycol and other glycols with a high surface tension as solvents, and instead used glycols with a low surface tension to promote ink penetration into the wet paper. We decided to mainly use glycol ether. However, there is absolutely no problem in mixing and using a portion of glycol for purposes such as adjusting the drying speed of the ink. Further, it is also possible to add other water-soluble solvents or a portion of water-insoluble solvents within a range that does not prevent the resin from precipitating on contact with water.

Examples of the main solvent glycol ether include butyl cellosolve, methyl, ethyl, propyl, butyl carbitol, and methyl, ethyl, propyl,
Butyl and triglycols can be used.
Further, as glycols, any of ethylene glycol and propylene glycol having different molecular weights from ethylene glycol to high molecular weight polyethylene glycol can be used in combination with glycol ether. Other water-soluble solvents such as mono-fatty acid esters of glycols, mono- or di-ethers, esters or aliphatic compounds of glycols,
Aromatic solvents that are partially soluble in water or insoluble in water can also be mixed and used.

The resin to be used is one that is soluble in the aforementioned glycol ethers alone or in a mixed solvent; however, if the resin is too soluble, the precipitation rate of the resin will be slow when the ink comes into contact with water, and the drying rate of the ink will be insufficient. , it is necessary to select the resin according to the solvent used. Resins suitable for this purpose include rosin-modified phenolic resins (for example, Tamanol manufactured by Arakawa Chemical Industries)
350), alkylphenol resin (Hitanol 1133 manufactured by Hitachi Chemical Co., Ltd.), xylene resin, coumaron resin, ester resin (Pensel®, Pencell A manufactured by Arakawa Chemical Co., Ltd.), ethyl cellulose, hardened rosin (Lime Resin No. 3, manufactured by Arakawa Chemical Co., Ltd., Lime) Resin No.
23C), styrene-maleic acid copolymer resin (Oxilac SH-101 manufactured by Nippon Shokubai Chemical Co., Ltd.), acrylic resin (Hyros AW-36 manufactured by Seiko Chemical Industry Co., Ltd.), cellulose acetate butyrate, butyral resin (Esslec BL-1 manufactured by Sekisui Chemical Co., Ltd., Esslec) BL-2), acid value is 200
Examples include the following rosin-modified maleic acid resin (Marquid resin manufactured by Arakawa Chemical Industries). Rosin-modified maleic acid resin (Marquid No. 33, manufactured by Arakawa Chemical Industries), which has a high acid value (approximately 300) and is commonly used in steam set inks, also has a slow drying rate when a large amount of diethylene glycol is mixed in the solvent. It was very effective.

An essential requirement of the present invention is the use of additives. Additives contribute to various effects, albeit in small amounts. That is, the bonding force between the resins in the vehicle or between the resin and the solvent is strengthened, preventing the ink from becoming an emulsion due to moisture contamination, suppressing ink thickening during printing, and reducing paper peeling. It is also effective in uniformly transferring ink, strengthening the ink film, and accelerating drying. Materials useful as additives include oleic acid, dehydrated castor oil, fatty acids, 2-ethylhexyl alcohol, castor oil, turpentine oil, dibutyl phthalate, dioctyl phthalate, tri-n-butyl phosphate, and low molecular weight hydroxypropyl cellulose. It will be done.

The coloring agent is mainly Raven 1035 (carbon black).
However, in this ink, which focused on preventing paper peeling, the amount of vehicle was increased considerably, so the pigment concentration had to be kept low. Naturally, pigments and dyes of other colors may be used as required.

Since the viscosity of the ink used is low, we investigated the printing mechanism to ensure that it adheres uniformly to the plate surface. That is, in order to enhance the printing effect on wet paper, the surface of the ink application roller on the metal plate surface of the letterpress was coated with a liquid-retaining material such as a damping sleeve (manufactured by 3M) that has the function of absorbing and retaining liquid substances. As a result, the amount of ink applied to the printing plate was constant, resulting in uniform printed figures and improved color density.

By the method described above, it was possible to clearly print the figure for the tree cutting mark on the wet paper.

Hereinafter, the composition of the wet paper printing ink will be explained in more detail with reference to Examples.

(The parts in each example are parts by weight.) Example 1 Solvent Butyl triglycol 70 parts Resin Cured rosin (Arakawa Chemical Co., Ltd. Lime Resin No. 3) 20 parts Additive Dioctyl phthalate 3 parts Colorant Carbon Black (Raben 1035 manufactured by Columbia Carbon) 7 parts For the kneading process, first mix the above components of solvent and resin in 1 part.
1 and heated to 200°C to dissolve the resin and obtain a vehicle with a viscosity of approximately 20 poise (30°C). Next, this vehicle and the black pigment as a colorant are kneaded in a three-roll mill to a pigment concentration of 20%, and this is used as the base ink, adding the vehicle, solvent, and additives that are insufficient in the composition, and uniformly using a high-speed stirrer. They were mixed to make a practical ink.

Using this ink composition, a tree cutting mark could be printed extremely clearly on wet paper by letterpress printing.

Example 2 Solvent Methyl triglycol 92 parts Resin Butyral resin (Sekisui Chemical's Eslec BL-2) 5 parts Additive 2-ethylhexyl alcohol 2 parts Colorant Oil dye (Orient Chemical Oil Blue #630) 1 part Above components A practical ink was prepared by mixing ingredients other than the coloring agent, heating to 120°C, melting, and cooling to 80°C, adding the coloring agent, stirring, and dissolving.

Using this ink composition, printing similar to that in Example 1 could be performed.

Example 3 Solvent Methyl triglycol 42 parts Diethylene glycol 42 parts Resin Rosin-modified maleic acid resin (Marquid No. 33 manufactured by Arakawa Chemical Industries) 10 parts Additive Oleic acid 1 part Colorant Carbon black (Carbon Black MA manufactured by Mitsubishi Chemical Industries, Ltd.) -100) 5 parts Diethylene glycol and resin of the above components 1 part
1 and heated to 200°C to dissolve the resin and obtain a vehicle with a viscosity of approximately 40 poise (30°C). This vehicle and black pigment as a coloring agent are kneaded in a three-roll mill to a pigment concentration of 20%, and this is used as a base ink, adding the vehicle, solvent, and additives that are insufficient in the composition, and mixing uniformly with a high-speed stirrer for practical use. Ink.

Using this ink composition, printing similar to that in Example 1 could be performed.

Claims (1)

[Claims] 1. Wet paper containing 60 to 75% moisture, where the fibers forming the paper layer are not yet fully bonded, such as wet paper immediately after press rolls on a paper machine, has a boiling point of 170%.
70-95% water-compatible solvent mainly consisting of glycol ether at temperature above ℃, 3-25% resin soluble in this solvent but insoluble in water, 0.5-10% coloring agent, addition for the purpose of preventing paper peeling. A wet paper printing method characterized by printing figures using ink containing 0.5 to 5% of a chemical agent as a component. 2. In the above-mentioned printing, an ink application roller whose surface is coated with a liquid-retaining material is held on the printing mechanism to uniformly transfer the ink to the plate surface to perform letterpress printing. The wet paper printing method according to item 1.