JPH02248293A - Method for treating surface of plate material for offset printing - Google Patents

Abstract

PURPOSE:To obtain printed matter of high quality by treating the surface of a plate material for offset printing, which is obtained by sulfonating the surface of a film or sheet composed of a filler-containing polymer of an ethylenic monomer, with an oxidizing agent. CONSTITUTION:A sulfonic acid group is imparted to the surface of a film or sheet composed of a filler-containing polymer of an ethylenic monomer by chemical forming treatment. The surface of this plate material for offset printing is treated with an oxidizing agent. By this method, no background staining or blurr is generated and printing durability and an ink fixing property are enhanced and printed matter of high quality is obtained.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to an offset plate material in which a sulfonic acid group is added to the surface of an ethylene polymer film or sheet containing a filler by chemical conversion treatment. , relates to a method for significantly improving the effect of adding fillers on the quality of printed matter by treating the surface with an oxidizing agent.

[Conventional technology and its problems]

The present inventors have previously disclosed in Japanese Patent Applications No. 181563/1983 and 193414/1983 that an offset having excellent printing properties was obtained by adding sulfonic acid groups to the surface of a polymer compound containing a filler. The company provided printing plates for the project. However, when printing using these plate materials, blurring, staining, mottling, etc. that can be seen with a magnifying glass sometimes occur, making it difficult to consistently produce high-quality printed materials. Something happened.

This is mainly due to foreign matter produced as a by-product during the sulfonation reaction adhering to the surface of the printing plate.
This phenomenon often occurred in the case of printing plates made from films or sheets containing fillers such as calcium carbonate.

[Means for solving problems]

The purpose of the present invention is to improve such problems, and by treating the surface of the above-mentioned plate material containing filler with an oxidizing agent, the quality of printed matter deteriorates due to scumming, blurring, etc. and the characteristics of the plate material improved by adding filler.
For example, the present invention was completed by discovering that the treatment can significantly improve stiffness, ink receptivity, etc.

That is, the present invention provides a method of treating the surface of an offset printing plate obtained by sulfonating the surface of a film or sheet made of a polymer of ethylene monomer containing a filler using an oxidizing agent. be.

In the present invention, the polymer compound constituting the resin composition of the film or sheet used as the offset plate material is a polymer of ethylene monomers, such as ethylene, propylene, butene-1,4-methylpentene-1, hexene. Homopolymers of olefins such as olefin-1 and octene-1, and/or mutual copolymers of the above monomers with a molecular weight of at least 10,000 or more are used. Among these, high-density polyethylene (density 0.94 to 0.97) produced by a low-pressure method or a medium-pressure method is particularly suitable.

In addition, the polymer compound may be one selected from vinyl halides or vinylidene halides, such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, ethylene trifluoride, propylene hexafluoride, and vinyl bromide. Those obtained by polymerizing two or more types of monomers or copolymerizing with at least one other monomer such as ethylene, propylene, butene-1, hexene-1, etc. can also be used. . Further, as a monomer having a polar group, one or two olefin compounds selected from nitrile groups such as acrylonitrile and methacrylonitrile, ester groups such as ethyl acrylate and methyl acrylate, and acetate groups such as vinyl acetate, etc. Polymerize two monomers or other monomers,
For example, ethylene, propylene, butene-1, hexene-
A polymer compound obtained by copolymerizing with at least one of the following compounds can also be used.

Fillers used in the present invention include carbonate fillers such as barium carbonate, calcium carbonate and magnesium carbonate, silicon-based inorganic fillers such as kaolinite, clay, wollastonite and white carbon, zinc white and magnesium oxide, etc. One or more fillers selected from metal oxide fillers and metal hydroxide fillers such as aluminum hydroxide and magnesium hydroxide can be used.

Moreover, these fillers can be used whose surfaces have been previously treated with a coupling agent such as azidosilane.

The amount of these fillers added is generally 10 to 70% by weight. If the amount added is less than 10% by weight, the inherent improvement effect of the filler, such as improving the ink receptivity and background smearing property of the printing press, is not so remarkable, and if the amount added is more than 70% by weight, it is difficult to form a film.

Additionally, compounding agents commonly used in molding polymeric compounds, such as addition of lubricants such as calcium stearate and heat stabilizers, can be used.

A known method can be used for manufacturing the film of the present invention.

There are no particular restrictions on the sulfonation method (for example, the film may be immersed in fuming sulfuric acid, or gaseous sulfuric anhydride may be used as is, or chloroform, carbon tetrachloride, ethylene dichloride, etc.) It is also possible to use a product diluted with an organic solvent that is relatively less active than sulfuric anhydride.

Oxidizing agents used in the present invention include acidic dichromate solutions, permanganate solutions, perchlorate solutions, vanadate solutions, hypochlorite solutions, hydrogen peroxide, and the like.

The concentration of oxidizing agent is usually 1-30%, and the treatment temperature is 0-80℃.
The processing time is 1 to 60 minutes, and the optimum processing conditions should be selected depending on the oxidizing agent and the type of plate material to be processed.

In general, offset printing plates obtained by sulfonating filler-containing polymer films and sheets have a yellow or reddish-brown color, but due to oxidizing agents, the color fades from a slight to a noticeable degree. It is desirable to carry out treatment. However, it is not preferable to carry out the treatment to the extent that it becomes almost colorless, since this will actually reduce the image forming properties and printability.

In particular, in the infrared absorption spectrum of the surface of the plate material subjected to the oxidation treatment in the present invention, the ratio of the absorbance of a strong band around wave number 1200 to the absorbance of a band attributed to sulfonic acid groups around wave number 1050 is small. (When both are 0.6, it is possible to omit the troublesome process of preparing a negative or positive film in advance and then exposing and developing the film through the film to produce a printing plate.

That is, a lipophilic image area can be chemically formed by scanning the hydrophilic surface using a modulated laser beam or a thermal head, so that a so-called direct lithographic plate that does not require a negative or positive film can be obtained. be able to.

In the present invention, the preferable degree of sulfonation on the surface of the plate material subjected to oxidation treatment is that the amount of sulfonation is 1×10 in terms of exchange equivalent.
˜5×10′. If the amount of sulfonation is less than 1X10', the hydrophilic effect due to the sulfonic acid group is small, making it unsatisfactory as a non-image area of a printing plate. On the other hand, it is generally difficult to obtain a sulfonation amount of 5 x 10' or more.

The sulfonation port can be determined as follows. That is, a film with a sulfonated surface (surface area Mad) is immersed in a 1N aqueous solution of calcium chloride to bring it to an equilibrium state, and the hydrogen chloride produced in the aqueous solution is reduced to 0.0N. Titrate with a specified sodium hydroxide aqueous solution (potency: f) to determine the neutralization value (X cc) with the indicator phenolphthalein,
Calculated using the following formula.

Sulfonated ff1 (milliequivalent/C) = (0, lX f X
It has great industrial value because it not only solves problems such as scumming and provides high-quality printed matter, but also generally further improves the effects of filler addition, such as improving printing durability and ink receptivity.

〔Example〕

The present invention will be specifically explained below using Examples.

Example 1 Copolymer of ethylene and ethyl acrylate containing 50% by weight of calcium carbonate (ethyl acrylate content at the start of polymerization 6.5 mol%, number average molecular weight about 30,000, crystallinity 6)
5%) film (approximately 150 microns thick)
It was immersed in fuming sulfuric acid containing 5% SO3 and allowed to react at room temperature for 50 minutes.

After the reaction was completed, the film was taken out, thoroughly washed with water, further immersed in 20% hydrogen peroxide solution, treated for 30 minutes, thoroughly washed with water, and dried.

The contact angle of this film was 18 degrees and the amount of sulfonation was 4.3X 10' mm/fA/cd.

Transfer printing of ultraviolet curing ink (Best Kikoa BFWRO Sumi, manufactured by Toka Shiki Co., Ltd.) was performed on the surface of the thus obtained film using a letterpress proofing machine (manufactured by Vandertack Co., Ltd.), and a distance of 1 m was applied using a water-cooled 3 kW ultra-high pressure mercury lamp. An image was formed by irradiating for 3 minutes to cure and adhere, and a printing plate was obtained.

When this printing plate was attached to an offset printing machine and printing was performed, high quality printed matter without background smearing was obtained. Subsequently, 10,000 copies were printed, but almost no scumming was observed, indicating that the effect of improving printing durability by adding calcium carbonate was significantly enhanced.

For comparison, an image was similarly formed on the sulfonated film without surface oxidation treatment using hydrogen peroxide, and then offset printing was performed.
．． Excellent printed matter was obtained up to 5,000 copies, but slight scumming was observed after 5,000 copies or more were printed.

Example 2 Polypropylene film containing 30% by weight of zinc white (
(density 0.91, thickness 150 microns) in a dry glass container, adjust the internal temperature from the outside to 0 to 5°C, and add SO3 gas/nitrogen gas (volume ratio 1/2). The reaction was carried out for 10 minutes while being introduced into the reaction vessel at a rate of 1 liter per minute.

After the reaction was completed, the film was taken out from the container and thoroughly washed with water. Further, the film surface was oxidized by immersion in a 10% aqueous solution of sodium hypochlorite for 20 minutes, then washed with water and air-dried.

The contact angle of this film is 12 degrees, and the amount of sulfonation is 5.2
XIO'mm per fi/cd, and the absorbance ratio of the infrared absorption spectrum was 1.1.

This film was pasted on a rotating roll, and while rotating at 2m/see, a semiconductor laser (manufactured by Sharp Corporation: LTO2) was applied.
7MD/MF, output 10 mW) was condensed with an optical lens and scanned to form an image of a single line and a solid area approximately 10 mm wide. Next, this was used as a printing plate and attached to an offset printing machine, and printing was performed to obtain printed matter with excellent ink density.

The ink receptivity of this printed matter was measured using a Courser reflection densitometer, and the inks used were New Champion, Cross (ink) manufactured by Dainippon Ink Co., Ltd., and Neo Alpha Maxi, Process (ink) manufactured by Oguchi Seika Co., Ltd. The values were 1.2 and 1.3, respectively, indicating that the addition of zinc white significantly enhanced the ink receptivity.

For comparison, the above-mentioned sulfonated film whose surface was not subjected to oxidation treatment with an aqueous solution of hypochlorous acid,
When an image was formed in the same manner and further printing was performed, the ink receptivity of both prints was 1.0.

Example 3 A high-density polyethylene film (number average molecular weight of about 100,000, thickness of about 150 microns) containing 50% by weight of calcined seaweed was set in a dry glass container, and the sulfonation reaction time was set to 25 minutes. Other than that, the same operation as in Example 2 was carried out to obtain a sulfonated film. Furthermore, this film was immersed in a 10% aqueous solution of sodium hypochlorite for 20 minutes to treat its surface, washed with water, and then air-dried.

The contact angle of this film is 13 degrees and the degree of sulfonation is 4.8.
X to -4 mm/fi/d, the absorbance ratio of the infrared absorption spectrum was 1.3.

Next, a word processor (manufactured by Sharp Corporation; "Shoin",
An image was formed by printing using a thermal head (Model WD-300F) to obtain a printing plate, and then offset printing was performed to give a printed matter of excellent quality without background smearing. The level of background smearing was so excellent that it could not be observed not only in a sensory test with the naked eye but also in observation using a magnifying glass. A further 5,000 copies were printed and the quality of the prints was equally excellent.

On the other hand, for comparison, an image was formed and printed in the same manner on the sulfonated film whose surface was not subjected to oxidation treatment with an aqueous sodium hypochlorite solution, and it was possible to obtain printed matter of excellent quality. Ta. However, after approximately 5,000 copies were printed, background smearing began to be observed. Judging using a magnifying glass, scumming had occurred in some places from the beginning of printing.

Example 4 A film of approximately 200 microns thick made of vinyl chloride resin (number average molecular weight approximately 50,000) containing 45% by weight of magnesium hydroxide was subjected to a sulfonation reaction for 90 minutes under the same conditions as in Example 2. . After the reaction was completed, the film was taken out, thoroughly washed with water, and further immersed in a 5% aqueous solution of sodium hypochlorite for 30 minutes to oxidize the film surface, washed with water, and air-dried. The contact angle of this film is 14 degrees, and the amount of sulfonation is t, 1xio' milliper fl/
ctl, the absorbance ratio was 0.9.

This film was pasted on a rotating roll and a helium/neon laser (manufactured by NEC Corporation, GLG5400, output IOMW
) was scanned over the surface of the film to form an image of a single line and a solid area with a width of 10 mm, thereby producing a printing plate. Next, this printing plate was attached to an offset printing machine and printing was carried out in the same manner as in Example 2 to obtain a printed matter in which the ink receptivity and background smearing property were significantly improved due to the addition of magnesium hydroxide. When the ink receptivity was measured using a Courser reflection densitometer, the inks using Dainippon Ink's New Champion, Cross (ink), and Dainichi Seika Chemical's Neo Alpha Maxi, Process (ink) were found to be They were 1.2 and 1.3, respectively. Furthermore, no background stains on the printed matter were observed even when observed using a magnifying glass.

For comparison, image formation was performed in the same manner on the sulfonated film described above without surface oxidation treatment using an aqueous solution of sodium hypochlorite, and further printing was performed.
The inking properties of the inks were 0.8 and 1.0, respectively.

In addition, although the background stains on the printed matter were not observed with the naked eye, they were observed in some places from the beginning of printing when observed with a magnifying glass.

〔Effect of the invention〕

By the method of the present invention, it was possible to easily obtain high-quality printed matter without scumming or blurring, and the printing durability and ink receptivity of the plate were improved.

Patent applicant: Asahi Kasei Industries, Ltd. teenager Reason Man

Claims (1)

[Claims] 1. A method of treating the surface of an offset printing plate obtained by sulfonating the surface of a film or sheet made of a polymer of ethylene monomer containing a filler using an oxidizing agent.