JP2572224B2 - Improved offset printing plate material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an offset printing plate material having a sulfonic acid group on its surface and excellent in printing durability. More specifically, it is an offset printing plate material that is sensitive not only to low-output laser light in the visible and near-infrared regions but also to a thermal head such as a thermal printing device and does not require development and fixing. For those with excellent printing power.

[Conventional technology]

Conventionally, a method of obtaining a printing plate used for offset printing includes (1) a so-called PS plate method, (2) a silver salt photographic method represented by a silver master method, and (3) an electrophotograph represented by an electrofax method. Laws and the like have already been developed and commercialized.

However, these methods require a step of obtaining a printing plate after forming a latent image by exposure, developing and fixing, and the plate making process is complicated, and the plate making machine itself becomes large, and In addition, there are problems such as soiling of hands in handling the developer.

The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, have invented a method of manufacturing an offset printing plate that does not require processing steps such as development and fixing, and have previously filed a patent application ( See Japanese Patent Application Laid-Open No. Sho 60-102632 and Japanese Patent Application Laid-Open No. Sho 60-132760).

[Problems to be solved by the invention]

However, since these printing plates also require high energy density of light energy, practically, for example, a xenon flash lamp of several hundred watts or a laser oscillator having an output of several watts or more must be installed. There was a point that needed to be improved.

The present invention significantly improves the plate-making properties of the offset printing plate material having the hydrophilic sulfonic acid group, and further improves the printing durability, for example, a 10-mW output He-Ne laser. By performing printing operations using a simple and compact thermal printer such as a word processor, or a thermal facsimile, etc., it is possible to easily obtain an offset printing plate and to provide a plate material having excellent printing durability. The purpose is to do so.

[Means for solving the problem]

That is, the present invention is a film or sheet of an olefin polymer compound having a polar group in the molecule, the surface of which is provided with a sulfonic acid group by a sulfonation reaction, and an infrared absorption spectrum of the surface, Wave number 1200
A plate for offset printing, characterized in that the ratio between the absorbance of a strong band attributed to a nearby sulfonic acid group and the absorbance of a band assigned to a sulfonic acid group near a wave number of 1050 is at least 0.6. It is.

Examples of the high molecular compound having a polar group include, for example, acrylonitrile, nitrile groups such as methacrylonitrile, ethyl acrylate, ester groups such as methyl methacrylate, olefin compounds having an acetate group such as vinyl acetate, and the like. One obtained by polymerizing one or more selected monomers or copolymerizing with at least one other monomer such as ethylene, propylene, butene-1, hexene-1, etc. It is the main material, and preferably has a water absorption of 2.0% or less. In general, like a polymer or a copolymer of a vinyl sulfonic acid group, a polymer compound originally having a sulfonic acid group,
Alternatively, those obtained by applying these polymer compounds to other base cloths are excluded because they are not suitable as printing plates due to the fact that the dimensional stability is reduced due to the large water absorption, and the characters are easily deformed. . The water absorption here refers to the rate of weight increase when immersed in water at a temperature of 20 ° C. for 24 hours.

Similarly, a polymer compound having a water absorption of 2.0% or more is not suitable because the dimensional stability of a printing plate obtained by sulfonation is low.

These olefin polymer compounds having a polar group in the molecule can be used as a film or sheet for other substrates, such as paper,
It may be used as a composite material bonded to glass cloth, glass paper, an aluminum plate, or the like.

There is no particular limitation on the method of sulfonation.For example, the film or sheet may be immersed in fuming sulfuric acid, or sulfuric anhydride may be used as it is or in chloroform, carbon tetrachloride, sulfuric anhydride such as ethylene dichloride, etc. On the other hand, it may be diluted with an organic solvent having relatively low activity.

Sulfonation conditions vary depending on the type of polymer used, but by performing the reaction using an oxidized sulfonating agent such as sulfuric anhydride, a structure having a strong band at a wave number of around 1200 in the infrared absorption spectrum is obtained. You can get things. This band indicates that at least a sulfonic acid group adjacent to a polyene structure having three conjugated double bonds has been formed, and it has been found that the sulfonic acid group exhibits photosensitivity or heat sensitivity. Was completed.

That is, the amount of the sulfonic acid group, compared with the amount of the general sulfonic acid group attributed to the wave number 1050, when the absorbance ratio is 0.6 or more according to the present invention, or offset excellent in heat sensitivity and heat sensitivity. Give a printing plate. In order to obtain such an excellent printing plate material of the present invention, when an oxidized sulfonating agent is used, it can be obtained by appropriately selecting the sulfonating temperature and time.

That is, in order to increase the ratio of the formation of sulfonic acid groups adjacent to the polyene structure, it is desirable to lower the sulfonation temperature, and the reaction temperature is usually −
30-70 ° C, preferably 0-40 ° C. If the sulfonation temperature is 70 ° C. or higher, various side reactions are likely to occur, and are excluded. On the other hand, below -30 ° C., the rate of formation of sulfonic acid groups adjacent to the polyene is low, which is economically undesirable
In addition, when sulfuric anhydride is used in a gaseous state as a sulfonating agent, the gas is liquefied and adheres to the wall of the inlet tube, which is liable to cause a process abnormality.

On the other hand, the sulfonation time must be selected depending on the temperature, for example, 5 to 60 minutes at 0 ° C. and 1 to 30 at 40 ° C.
Minutes is a preferred range.

In addition, other oxidizing low sulfonating agents generally used industrially, such as chlorosulfonic acid, phosphoric sulfonic acid, adducts of sulfuric anhydride with dimethylformamide or dioxane, etc., are adjacent to the polyene structure. Since the production amount of general sulfonic acid groups is superior to the production of sulfonic acid groups, it is difficult to increase the absorbance ratio to 0.6 or more, and special measures are required.

When the amount of sulfonation is 5 × 10 ^-5 to 1 × 10 ^-1 meq / cm ² in exchange equivalent, it gives hydrophilicity necessary for forming a non-image portion in an offset printing plate, and generally, As the amount of sulfonation increases with the progress, the hydrophilicity also improves, but the ratio of the absorbance is not always linear with the amount of sulfonation, so the optimal conditions must be selected for each polymer. . The amount of sulfonation is determined as follows. That is, a film having a sulfonated surface (surface area M cm ² ) is immersed in a 1N aqueous solution of calcium chloride to make an equilibrium state, and hydrogen chloride generated in the aqueous solution is converted into a 0.1N aqueous solution of sodium hydroxide (titer: Determine the neutralization value (Xcc) with the indicator phenolphthalein by titration in f) and calculate with the following formula.

Sulfonation amount (milli-equivalent / cm ² ) = (0.1 × f × x) / M The absorbance ratio referred to in the present invention is determined by using a baseline method generally adopted in the analysis of infrared absorption spectrum. That is, the wave number 1050 and attributed to the sulfonic acid group
Strong band around 1170 and wave number 1200 specified by the present invention
The ratio of the absorbance of the corresponding band is determined based on the baseline common to the nearby strong bands. The infrared absorption spectrum of the sulfonated compound can be measured by a reflection method (ATR method). It is known that non-photosensitive general sulfonic acid groups usually show two strong bands characteristic around the wave number of around 1050 and around the wave number of 1170, but further around the wave number of around 1200, preferably around the wave number of around 1200 to 1230. Said sulfonate having a photosensitive sulfonic acid group showing a similar strong band, the absorbance of the band attributed to the photosensitive sulfonic acid group near the wave number 1200, the sulfonic acid group near the wave number 1050 When the ratio with the absorbance of the band to be performed is 0.6 or more,
An object of the present invention is to provide a high-sensitivity and improved printing plate material for offset printing. It is generally difficult to obtain one having an absorbance ratio of 2.3 or more, and the absorbance of a sulfonate having the sensitivity required for plate making using a widely used thermal head is preferably 1.1 to 1.8.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

Example 1 A film made of a copolymer of ethylene and ethyl acrylate (ethyl acrylate content at the start of polymerization: 6.5 mol%, thickness: about 150 μ, water absorption: 1.5%) was set in a dry glass container. It was externally cooled so that the temperature was 0 to 5 ° C. On the other hand, sulfuric anhydride gas obtained by introducing dry nitrogen gas from the outside to the gas generator containing sulfuric anhydride is cooled from the outside so that the temperature becomes 0 to 5 ° C., and introduced into the reaction vessel. The reaction was performed for about 25 minutes. After the reaction was completed, the film was taken out of the container, washed with water and dried.

The sulfonation amount of this film is 5.2 × 10 ^-3 meq / cm
^2. The absorbance ratio of the infrared absorption spectrum was 1.7.

 The above film was converted to a word processor (Sharp;
"Shoin" , Model WD-300F) with a thermal head
Printed.

The plate prepared in this manner was mounted on an offset printing machine and printing was performed on 10,000 sheets. As a result, a printed matter with clear characters was obtained.

Example 2 A commercially available polyacrylonitrile sheet (Zeklon, manufactured by Mitsui Toatsu Chemicals, Inc., water absorption 0.7%) was treated with about 15% sulfuric anhydride.
% In an ethylene dichloride solution containing
Sulfonation reaction by immersion for 30 hours and sulfonation amount 5.1
A film having × 10 ⁻⁴ meq / cm ² and an absorbance ratio of 1.1 was obtained. Next, this film was affixed to a rotating roll, the beam diameter oscillated by a yag laser (NEC; SL129, output 50mw) was focused to 40μ, and the roll was set at a peripheral speed of 200cm / sec and irradiated. Offset printing 1 as in Example 1
I went to 0,000 sheets. The width of the image was about 42μ, and there was no fattening phenomenon and it was clear.

Example 3 A 150 μm thick sheet (1.8% water absorption) made of an ethylene-vinyl acetate copolymer (monomer ratio at the time of polymerization; 95: 5, density 0.93) was subjected to the method of Example 1 at 30 ° C. for 15 minutes. A sulfonation reaction was performed. The degree of sulfonation was 2.3 × 10 ⁻³ meq / cm ² , and the absorbance ratio was 1.2.

This film was printed using a word processor in the same manner as in Example 1, and was set on an offset printing machine to print 10,000 sheets. As a result, clear printed matter was obtained and no generation of background stain was observed.

Comparative Example 1 A film made of a copolymer of ethylene and ethyl acrylate (used in Example 1) was subjected to a sulfonation reaction at 60 ° C. for 10 minutes according to the method of Example 1. After completion of the reaction, the reaction solution was sufficiently washed with water and air-dried. The sulfonated amount of this film was 3.6 × 10 ⁻³ meq / cm ² , and the absorbance ratio was 0.5.

Next, this film was printed using a word processor in the same manner as in Example 1, and offset printing was performed, but the formation of characters was insufficient.

〔The invention's effect〕

By using the offset printing plate material of the present invention,
As described above, a printing plate can be easily manufactured. Therefore, for example, when a reading and writing mechanism of a facsimile and an offset printing machine are connected via the printing plate material of the present invention, printing of high-quality characters (mass copying) as a fully automatic printing machine is performed. Can be easier. Furthermore, since a computer (workstation) having an editing / composing function and an offset printing machine can be easily connected, a simple plate making /
Since a printing system can be provided and the printing durability is excellent, there is an advantage that a large amount of printed matter can be manufactured.

Claims (1)

(57) [Claims] 1. A film or sheet of an olefin polymer having a polar group in a molecule, to which a sulfonic acid group has been provided on the surface by a sulfonation reaction, wherein the film or sheet has an infrared absorption spectrum Absorbance of strong band attributed to sulfonic acid group near wave number 1200 and wave number 1050
A plate material for offset printing, wherein the ratio to the absorbance of a band attributed to a nearby sulfonic acid group is at least 0.6.