JP2745314B2 - Plate material for offset printing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an offset printing plate material comprising a polymer of an ethylene-based monomer having a sulfonic acid group on its surface and a silicon-based inorganic filler and having a small amount of background soil. is there.

[Conventional technology]

The present inventors have previously disclosed an offset printing plate material having a sulfonic acid group on the surface of a polymer compound in JP-A-60-52392. Also, Japanese Patent Application No. 62-83071 discloses offset printing that does not require development and fixing processing because it is sensitive not only to low-output laser light in the visible and near-infrared regions but also to thermal heads such as thermal printers. Plate materials are also provided.

[Problems to be solved by the invention]

An object of the present invention is to provide an improved printing plate material with less occurrence of background contamination.

Although a resin composition comprising a polymer compound and an inorganic filler is generally well known, it has not yet been used for an offset printing plate. This is because a conventional printing plate employs a method in which an image is formed by curing a photosensitive resin in an exposure step and then eluting an unexposed part in a development step. This is because the addition of the filler has a disadvantage that the photosensitivity and the resolution are reduced.

[Means for solving the problem]

However, the present inventors have found that when a film or sheet whose surface has been hydrophilized by a sulfonation reaction is used as a printing plate, the inorganic filler present in the resin layer has almost no effect on photosensitivity and image resolution. The present invention has been found not only to have little effect, but also to surprisingly reduce the occurrence of background stain on printed matter, and has completed the present invention.

That is, the present invention sulfonates a film or sheet comprising a polymer of an ethylene-based monomer and a silicon-based inorganic filler, and absorbs a strong band at a wave number of around 1200 and a wave number of around 1050 in an infrared absorption spectrum of the sulfonated surface. Forming a chemically lipophilic image area on the surface by scanning with a modulated laser beam or a thermal head, consisting of one having a ratio to the absorbance of the band attributed to the sulfonic acid group of at least 0.6. The present invention provides a printing plate material for offset printing that can be performed.

In general, it is extremely important to obtain a printed matter free of background stains in offset printing, and a great deal of effort is spent to set optimal printing conditions.However, the present invention provides a printing plate with less background stains. This has great industrial value.

In the present invention, a polymer of an ethylene-based monomer is used as a polymer compound constituting the resin composition of the film or sheet subjected to sulfonation. For example, ethylene,
A homopolymer of an olefin such as propylene, butene-1, 4-methylpentene-1, hexene-1, octene-1, or / and a mutual copolymer of the above-mentioned monomers, having a molecular weight of at least 10,000 or more; There are things. In particular, high-density polyethylene (density 0.94 to 0.97) produced by a low-pressure method or a medium-pressure method is suitable. On the other hand, as the polymer compound, for example, one selected from vinyl halide or vinylidene halide such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, ethylene trifluoride, propylene hexafluoride, and vinyl bromide, or Polymerize two or more monomers or other monomers, such as ethylene,
When the main material is obtained by copolymerization with at least one of propylene, butene-1, hexene-1, and the like, the sulfonation rate is increased in the sulfonation reaction so that the ratio of the unsaturated halogen compound increases. Therefore, there is a drawback that the sulfonic acid is delayed, but it is practically preferable because the photosensitivity of the obtained sulfonic acid is increased.

Further, as the monomer having a polar group, one or two or more selected from nitrile groups such as acrylonitrile and methacrylonitrile, ester groups such as ethyl acrylate and methyl acrylate, and olefin compounds having an acetate group such as vinyl acetate. Polymer compounds obtained by polymerizing at least one kind of monomer or copolymerizing with at least one kind of other monomer such as ethylene, propylene, butene-1, hexene-1 and the like can be mentioned.

In the present invention, when the silicon-based inorganic filler composition of the crystalline polymer compound is formed into a film or sheet, and a surface having a hydrophilic property imparted by a sulfonation reaction is used as an offset printing plate, Great effect of preventing occurrence. Here, the crystalline polymer compound is, for example,
It refers to those generally known as crystalline polymer compounds such as polyethylene and polypropylene, but shows diffraction spots due to the crystal region in the X-ray diagram, shows a clear melting point in differential thermal analysis, and shows mechanical properties such as tensile strength. It is defined as an improvement in physical properties due to the crystal structure in physical properties. The degree of crystallinity varies depending on the type of resin used, the conditions of the sulfonation treatment, and the like, so it is difficult to limit the optimum range. Known as non-crystalline, also non-ethylene polymer compounds, for example, when using a film made of a silicon-based inorganic filler composition of polystyrene, because the effect of preventing the occurrence of background fouling and image formation is poor Not preferred.

As the silicon-based inorganic filler in the present invention, one or more kinds of pulverized natural minerals, industrially purified and pulverized natural minerals, and industrially synthesized ones can be used. As the former natural products, for example,
Kaolinite, clay, calcined clay, pyroxene clay (pyrophyllite), sericite (sericite), mica, etc., mainly composed of aluminum silicate, wollastonite, zonolite, mainly composed of calcium silicate, There are those mainly composed of magnesium silicate such as talc and asbestos, and those mainly composed of silicic acid such as diatomaceous earth, silica stone and silica sand. Examples of the latter synthetic product include silicic anhydride, hydrated calcium silicate, and hydrated aluminum silicate, which are generally called white carbon.

These silicon-based inorganic fillers are spherical, needle-like, fiber-like, or flake-like having various aspect ratios, and any shape can exhibit the effect of reducing background contamination. Further, a material which has been treated with a silane coupling agent such as gamma-methacryloxypropyltrimethoxysilane can be used.

Further, the addition amount of the silicon-based inorganic filler is 10 to 70.
% By weight. At 10% by weight or less, the effect of preventing background contamination is not so remarkable. At 70% by weight or more, it is difficult to form a film, and since the obtained film has low mechanical properties such as tensile strength, it is suitable as an offset printing plate. Not.

In the present invention, a known method can be used as a method for producing a film. For example, a polyethylene powder and a predetermined amount of clay are added to a blender, calcium stearate or the like is added as a lubricant, mixing is performed, and the mixture is kneaded with a twin-screw extruder or a Banbury mixer, and is then pelletized. A method for obtaining a film can be used.

The method of sulfonation in the present invention is not particularly limited. For example, the film may be immersed in fuming sulfuric acid, or sulfuric anhydride may be used as is, or chloroform, carbon tetrachloride, sulfuric anhydride such as ethylene dichloride, etc. May be used by diluting with an organic solvent having relatively low activity.

In the present invention, the preferred degree of sulfonation is such that the sulfonation amount is 5 × 10 ^-6 to 1 × 10 ^-1 in exchange equivalent. When the sulfonation amount is 5 × 10 ⁻⁶ or less, the effect of the hydrophilicity due to the sulfonic acid group is small, so that it is insufficient as a non-image portion of the printing plate, and stains occur. On the other hand, the sulfonation amount was 1 × 10
Conditions under which ⁻¹ or more are obtained are not suitable because the degree of oxidative deterioration increases as a side reaction.

The degree of hydrophilicity can be determined by measuring the contact angle of a water droplet on the film surface. Generally, the preferred contact angle for the non-image portion of the printing plate is 30 degrees or less.
The amount of sulfonation can be determined as follows. That is, a film having a sulfonated surface (surface area Mc
m ² ) was immersed in a 1N aqueous solution of calcium chloride to equilibrate, and the hydrogen chloride generated in the aqueous solution was titrated with a 0.1N aqueous solution of sodium hydroxide (titer: f) to give an indicator phenolphthalein. The neutralization value (Xcc) is calculated by the following formula.

Sulfonation amount (milli-equivalent / cm ² ) = (0.1 × f × X) / M One method for producing the photosensitive and heat-sensitive material according to the present invention is to sulfonate a polymer material using the above-described method. It is.

A film or sheet made of the above-described polymer composition whose surface has been hydrophilized by a sulfonation reaction as a non-image portion of a printing plate, or removing a portion corresponding to an image portion from the hydrophilic surface layer, Alternatively, a printing plate can be obtained by forming an lipophilic image area on the hydrophilic surface layer. A mechanical or thermal method can be used as a method of creating an image portion by removing the portion corresponding to the former image portion. For example, only the surface may be scraped off with an iron brush or a cutter to draw, or it may be thermally removed by a laser. In the latter case, the lipophilic image area is formed by coating a photosensitive agent on the hydrophilic surface layer in the same manner as in a normal lithographic method, drying and providing a photosensitive layer, and exposing the photosensitive layer through a negative or positive original. Done and then developed. The photosensitive agent used here is a known one, for example, a photosensitive material mainly composed of various photosensitive resins such as a dichromate type, a diazonium salt type, an O-quinonediazo type, a silicate ester type and the like.

In particular, in the present invention, the offset printing plate material of Japanese Patent Application No. 62-83071, that is, the infrared absorption spectrum of the hydrophilic surface obtained by the phonation treatment, absorbance of a strong band having a wave number of around 1200 and sulfone having a wave number of around 1050 When an offset printing plate having a ratio of absorbance of a band attributed to an acid group to the absorbance of the band (hereinafter, referred to as “absorbance ratio”) of at least 0.6 is prepared, the above negative or positive film is prepared and exposed and processed. It is possible to omit complicated steps such as development. That is, by scanning with a laser beam or a thermal head or the like modulated on the hydrophilic surface layer, a lipophilic image area can be chemically formed, and the steps of development and fixing are not required. Thus, an offset printing plate with little occurrence of background stain can be obtained, and thus has a great industrial value.

〔Example〕

 Hereinafter, the present invention will be described specifically with reference to Examples.

Example 1 High-density polyethylene film containing 30% by weight of kaolinite (number average molecular weight: about 100,000, thickness: about 150 microns)
Was immersed in fuming sulfuric acid containing 40% SO ₃ and reacted at room temperature for 50 minutes. After completion of the reaction, the film was taken out, washed sufficiently with water, neutralized with an aqueous sodium hydroxide solution, washed well with water, and dried. The contact angle of the obtained film was 16, and the sulfonation amount was 8.2 × 10 ⁻⁵ meq / cm ² .

The UV curable ink (Toka Dye, Best Cure, BF-WRO Black) is transferred and printed on the surface of the film hydrophilized by the sulfonation reaction using a letterpress proofing machine (manufactured by Binder Cook Co.), and then cooled with water. A printing plate was obtained by irradiating the ink image portion on a hydrophilic surface by irradiating the ink image portion on a hydrophilic surface for 3 minutes at a distance of 1 m using a 3 kW ultra-high pressure mercury lamp.

When this printing plate was attached to an offset printing machine and printing was performed, a high-quality printed matter with no background stain was observed with the naked eye.

Example 2 A copolymer of ethylene and ethyl acrylate containing 10% by weight of silica (ethyl acrylate content at the start of polymerization)
6.5 mol%, number average molecular weight approx. 30,000, crystallinity 65%), set a 150 micron thick film in a dry glass container, and adjust it from outside so that the internal temperature is 45 ° C. While adjusting the SO ₃ gas / nitrogen gas (volume ratio 1/2) to 1 liter per minute and introducing it into the reaction vessel, 15
The reaction was performed for minutes. After completion of the reaction, the film was taken out of the container, immediately neutralized with an aqueous sodium hydroxide solution, washed well with water, and dried. The contact angle of this film is 12 degrees, and the sulfonation amount is 3.1 × 10 ^-3 meq / cm ²
Met.

On the surface of the hydrophilized film thus obtained,
A photosensitive resin comprising an acrylic resin having an unsaturated group in a side chain, a monomer and a photosensitizer prepared by the method described in Example 1 of JP-B-49-34041 is dried using a wire bar. The photosensitive layer was provided so that the subsequent coating amount was 4 g / m ² . Next, a negative film is applied to the photosensitive layer surface,
After exposure for 60 seconds from a distance of 1m using a water-cooled 3kW ultra-high pressure mercury lamp, sodium phosphate 1% by weight and methanol 10%
The photosensitive layer in the unexposed areas was removed by developing with an aqueous solution containing 5% by weight, and a lipophilic image area was provided on the hydrophilic surface to prepare a printing plate.

The printing plate thus obtained was attached to an offset printing machine and printing was performed. As a result, a good printed matter having no background stain was obtained.

Example 3 A high-density polyethylene film (number-average molecular weight: about 100,000, thickness: about 150 microns) containing 30% by weight of calcined clay was set in a dry glass container, the internal temperature was set to 0 to 5 ° C, and the reaction time was set. The operation was performed in the same manner as in Example 2 except that the drying time was changed to 25 minutes to obtain a hydrophilic film. The contact angle of this film is 15 degrees, the sulfonation amount is 1.4 × 10 ^-4 meq / c
m ² and the absorbance ratio were 1.2. Next, this film was adhered to a rotating roll, and a beam focused by a helium-neon laser (manufactured by NEC; GLG5400, output 10 mW) with a beam diameter of 20 μm was scanned. The rotation speed of the roll was set to 2 m / sec. When the printing thus prepared was attached to an offset printing machine and printing was performed, a clear image having a line width of 21 microns was obtained. No soiling was observed.

Example 4 A film having a thickness of about 200 μm made of a vinyl chloride resin (number average molecular weight of about 50,000) containing 50% by weight of diatomaceous earth was subjected to a sulfonation reaction for 40 minutes under the same conditions as in Example 3 to obtain a hydrophilic property. Was obtained. The contact angle of this film is 12
Degree, sulfonation amount is 2.3 × 10 ^-4 meq / cm ² , absorbance ratio
1.1. Paste this film on a rotating roll, 2m /
A printing plate was produced by condensing a semiconductor laser (LT027MD / MF, output 10 mW) with an optical lens and scanning while rotating at a speed of sec. Next, this printing plate was attached to an offset printing machine and printing was performed.
Micron clear image was obtained. No soiling was observed on the printed matter.

Example 5 Ethylene containing 65% by weight of white carbon and 4-
Methylpentene-1 copolymer (4-methylpentene-1 content at the start of polymerization: 3 mol%, number average molecular weight: about 30,000)
Was subjected to sulfonation under the same conditions as in Example 3 to obtain a hydrophilic film. The contact angle of this film was 12 degrees, the sulfonation amount was 7.5 × 10 ⁻⁴ meq / cm ² , and the absorbance ratio was 1.4.

Next, a word processor (Sharp Corp .;
Hospital " , Model WD-300F) and print with thermal head
did. The plate prepared in this way is used for an offset printing machine.
When the printing was carried out by attaching, a clear printed matter was obtained. This
No smear was observed on the printed matter.

Example 6 A high-density polyethylene film (number average molecular weight: about 50,000, thickness: about 150 microns) containing 50% by weight of silica was set in a dry glass container, the internal temperature was set to 0 to 5 ° C, and the reaction time was set to Except for 7 minutes, the same operation as in Example 2 was performed to obtain a hydrophilic film. The contact angle of this film was 14 degrees, the sulfonation amount was 5.8 × 10 ⁻⁶ meq / cm ² , and the absorbance ratio was 0.9. Next, this film is attached to a rotating roll, and a helium / neon laser (manufactured by NEC; GLG540) is used.
(0, output of 10 mW) was scanned with light condensed to a beam diameter of 15 microns. The rotation speed of the roll was set to 3.0 m / sec.

When the printing thus prepared was attached to an offset printing machine and printing was performed, a clear image with a line width of 17 microns was obtained. No soiling was observed in the printing of 2,000 copies.

Comparative Example 1 High-density polyethylene film containing 8% by weight of kaolinite (number average molecular weight: about 100,000, thickness: about 150 microns)
Was performed in the same manner as in Example 1 to obtain a printing plate, and then an offset printing plate was prepared. This printed matter had background stains that could be recognized with the naked eye.

Comparative Example 2 Kaolinite (71% by weight) and high-density polyethylene (number average molecular weight: about 50,000) were kneaded using a Banbury mixer, and then a 150-micron film was produced using a T-die extruder. Was difficult to get. Further, the obtained film was brittle and was not suitable as a printing plate material.

Comparative Example 3 A polystyrene film (number-average molecular weight: about 30,000, thickness: 150 μm), which is an aromatic and amorphous polymer compound containing 23% by weight of kaolinite, was sulfonated under the same conditions as in Example 3. Thereafter, an image was formed on the surface by the method of Example 1. When the printing plate thus obtained was mounted on an offset printing machine and printing was performed, background staining was remarkable. Printing was performed using the thermal head according to the method of Example 5, but no image was formed.

Comparative Example 4 Copolymer of ethylene and ethyl acrylate containing 23% by weight of kaolinite (ethyl acrylate at the start of polymerization)
A printing plate having a thickness of 150 μm and comprising 30 mol%, a number average degree of polymerization of about 30,000 and a crystallinity of 18%) was prepared in the same manner as in Example 3, and then an offset printing plate was prepared.

The line width of the printed matter was about 10 microns and the sharpness was poor.
In addition, soiling was observed in some places.

〔The invention's effect〕

The present invention provides an offset printing plate material in which the steps of development and fixing can be simplified and the occurrence of background contamination is extremely small. It can be said that there is a great industrial effect on the industry that has prevented contamination.

Claims (1)

(57) [Claims] 1. A film or sheet comprising a polymer of an ethylene-based monomer and a silicon-based inorganic filler is sulfonated, and in the infrared absorption spectrum of the sulfonated surface, the absorbance of a strong band having a wave number of about 1200 and the wave number of 1050 are obtained.
A chemically lipophilic image area is formed on the surface by scanning using a modulated laser beam or a thermal head, which is composed of one having a ratio of absorbance of a band attributed to a nearby sulfonic acid group to at least 0.6. A plate material for offset printing that can be formed.