JP2745317B2 - Plate material for offset - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an offset printing plate material comprising an ink composed of an ethylene-based monomer polymer having a sulfonic acid group on the surface and having improved inking property and background soiling property.

[Conventional technology and problems]

In recent years, the development of offset printing has been remarkable, occupying more than 70% of the printed matter, but the disadvantage is that the ink density of the printed matter is relatively low. In offset printing, the ink attached to the plate surface is transferred to a rubber roll and then transferred to paper for printing.For example, in the PS plate, the amount of ink received on the resist surface forming the image area is reduced. It is caused by being small. As a method of improving this, for example, ink composition or fountain solution composition,
It is a simple method to increase the amount of ink adhering to the resist surface layer by adjusting printing conditions, but this method often causes background contamination.
As described above, in the conventional plate material, it is generally difficult to satisfy both the inking property and the background stain property of the ink.

In order to overcome this situation, the present inventors first disclosed in
JP-52392A provides a lithographic printing plate material having a sulfonic acid group on the surface of a polymer compound. In addition,
Japanese Patent Application Laid-Open No. 62-83071 provides not only low-output laser light in the visible and near-infrared regions but also an offset printing plate material that is sensitive to a thermal head such as a thermal printer and does not require development and fixing processes. ing.

However, it is desirable to further improve these techniques.

[Means for solving the problem]

In order to solve the above-mentioned problems, the present inventors focused on improving the ink concentration of a printed material, and were made of a polymer of an ethylene-based monomer and a metal hydroxide showing a higher ionization tendency than hydrogen in an ionization train. A film or sheet containing a filler as a main material is sulfonated, and a wave number of 12 in an infrared absorption spectrum of the sulfonated surface is obtained.
The ratio between the absorbance of the strong band around 00 and the absorbance of the band attributable to the sulfonic acid group near the wave number of 1050 is at least 0.
Excellent ink inking property and background soiling that can form a chemically lipophilic image area on the surface by scanning using a modulated laser beam or a thermal head consisting of It has been invented that an offset printing plate having the following can be obtained.

In general, a resin composition comprising a polymer compound and a hydroxide of a metal such as magnesium hydroxide is well known, but has not been used as a plate material for offset printing.
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.

However, a film mainly composed of an ethylene-based monomer polymer and a filler of a metal hydroxide, or a sheet obtained by hydrophilizing the surface of a sheet by a sulfonation reaction to form a printing plate, is present in the resin layer. Not only did the inorganic filler have little effect on the photosensitivity and the resolution of the image, but it was also possible to greatly improve the inking property and background stain of the ink.

In the present invention, a polymer of an ethylene-based monomer is used as the polymer compound constituting the resin composition of the film or sheet subjected to sulfonation. For example, ethylene, propylene, butene-1,4-methylpentene-
1, homopolymers of olefins such as hexene-1, octene-1 and / or mutual copolymers of the above-mentioned monomers having a molecular weight of at least 10,000 or more.
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 halides or vinylidene halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, ethylene trifluoride, propylene hexafluoride, and vinyl bromide, or Examples thereof include those obtained by polymerizing two or more monomers or copolymerizing with at least one of other monomers such as ethylene, propylene, butene-1, hexene-1, and the like.

Further, as a monomer having a polar group, one or two 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. Polymerizing one or more monomers or other monomers such as ethylene, propylene, butene-
And high molecular compounds obtained by copolymerizing with at least one of hexene-1 and the like.

In the present invention, a printing plate obtained by forming a composition of a crystalline polymer compound and a filler of a metal hydroxide as an ethylene-based monomer polymer into a film or sheet and imparting hydrophilicity to the surface thereof by a sulfonation treatment. When used as, a product excellent in image forming properties can be provided. Here, the crystalline polymer compound refers to, for example, a compound generally known as a crystalline polymer compound such as polyethylene and polypropylene. It is defined as exhibiting a clear melting point and improving physical properties due to the crystal structure in mechanical properties such as tensile strength. 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.

In addition, when a film composed of a polymer compound mainly composed of a polymer compound known as non-crystalline, for example, polystyrene and a filler of a metal hydroxide, is used, only background dirt easily occurs. However, it is not preferable because the image formability is poor.

As the filler comprising a metal hydroxide in the present invention, a metal having a higher tendency to ionize than hydrogen in the ionization column, for example, hydroxides of potassium, calcium, sodium, magnesium, aluminum, zinc, iron, nickel, tin, etc. be able to. In particular, as the filler which is inexpensive and has excellent handleability, for example, magnesium hydroxide and aluminum hydroxide can be mentioned. As the magnesium hydroxide, those naturally produced as "bluesite" and those industrially produced from seawater by the "ion bitter method" can be used.

In general, aluminum hydroxide manufactured by the Bayer method using bauxite as a raw material can be used. Further, depending on the melting point and processing conditions of the resin used,
Those leading to the composition of Al (OH) ₃ or Al ₂ O ₃ · 3H ₂ O comprised AlO from the "gibbsite" represented by the chemical formula (OH) or "boehmite" represented by Al ₂ O ₃ · H ₂ O You can choose.

Furthermore, fillers composed of hydroxides of these metals and having a small average particle size are suitable for obtaining high-resolution and high-quality printed matter. On the other hand, if the diameter is 5 μm or more, unevenness of ink adhesion is generated, and it is easy to cause blurring, which is not preferable. Further, it is possible to use a filler whose surface has been treated in advance using a coupling agent such as azidosilane.

In the present invention, the effective addition amount of the filler comprising the metal hydroxide is 10 to 70% by weight. At an addition amount of 10% by weight or less, the effect of improving the inking property and background stain of the ink is not so remarkable, and at an addition amount of 70% by weight or more, it is difficult to form a film, and the obtained film has a tensile strength and the like. Excluded due to low mechanical properties. Further, a compounding technique used in molding a polymer compound, such as addition of a lubricant such as calcium stearate or a heat stabilizer, can be employed.

In the present invention, a known method can be used as a method for producing a film. For example, a method of adding a polyethylene powder and a predetermined amount of magnesium hydroxide to a blender and mixing, kneading with a twin-screw extruder or a Banbury mixer, forming pellets, and using a T-die extruder to obtain a film. Can be used.

There is no particular limitation on the method of sulfonation in the present invention.For example, the film may be immersed in fuming sulfuric acid, or gaseous sulfuric anhydride may be used as it is,
Alternatively, it may be diluted with an organic solvent having a relatively low activity with respect to sulfuric anhydride such as chloroform, carbon tetrachloride and ethylene dichloride.

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. If the amount of sulfonation is 5 × 10 ⁻⁶ or less, the effect of the hydrophilicity of the sulfonic acid group is small, so that it is not sufficient as a non-image portion of the printing plate, and background stain is likely to occur. On the other hand, when the sulfonation amount is 1
It is not appropriate under the conditions to obtain those of × 10 ⁻¹ or more because the degree of oxidative deterioration as a side reaction increases.

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 Mcm
² ) is immersed in a 1N aqueous solution of calcium chloride to equilibrate the solution, and the hydrogen chloride generated in the aqueous solution is titrated with a 0.1N aqueous solution of sodium hydroxide (titer: f). The neutralization value (Xcc) is obtained and calculated by the following equation.

Sulfonation amount (milli-equivalent / cm ² ) = (0.1 × f × X) / M One method for producing the photosensitive and photosensitive material according to the present invention is to combine the above-mentioned polymer material with a metal hydroxide filler. By sulfonating about 150 micron thick sheets of the main composition with sulfuric anhydride.

When the surface of the film or sheet hydrophilized by this sulfonation reaction is observed with a magnifying glass, countless micropores which are considered to have eluted with some of the fillers together with the fillers can be recognized. The film or sheet hydrophilized in this way is used as a non-image portion of a printing plate, and an oleophilic image portion is formed on the hydrophilic surface, thereby improving the inking property and background stain of the ink. Offset printing plate can be obtained.

In particular, in the present invention, in the infrared printing spectrum of the hydrophilic surface obtained by the sulfonation treatment, the absorbance of a strong band having a wave number of around 1200 and the sulfone having a wave number of around 1050 in the offset printing plate material of Japanese Patent Application No. 62-83071. When the offset plate having a ratio of at least 0.6 to the absorbance of a band attributed to an acid group is used as an offset plate material, a negative or positive film is prepared in advance, and then exposed and developed through the film to produce a printing plate. It is possible to omit the cumbersome process of performing the operation. 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 formed chemically. However, steps such as development and fixing are not required as compared with a general lithographic plate. Furthermore, compared to the conventional offset plate material,
Since it is possible to obtain an offset printed matter excellent in the inking property and background stain of the ink, the industrial value is great.

〔Example〕

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

Example 1 Magnesium hydroxide (Kisuma 5B, manufactured by Kyowa Chemical Industry Co., Ltd.)
A high-density polyethylene film (number average molecular weight: about 100,000, thickness: about 150 microns) containing 40% by weight was immersed in fuming sulfuric acid containing 40% SO ₃ and reacted at room temperature for 90 minutes. After completion of the reaction, the film was taken out, washed sufficiently with water, and dried. The contact angle of water droplets on the surface of the film thus obtained is 15 degrees, and the sulfonation amount is
1.2 × 10 ⁻⁴ meq / cm ² .

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 later coating amount was 3.2 g / m ² .

Next, a negative film is applied to the surface of the photosensitive layer, and is cooled with water.
After exposure for 60 seconds from a distance of 1m using a 3kw ultra-high pressure mercury lamp, 1% by weight of sodium phosphate and 10% by weight of methanol
The film was developed with an aqueous solution of the following to remove the unexposed portion of the photosensitive layer, and a lipophilic image portion was provided on the hydrophilic surface of the film to prepare a printing plate.

When the printing plate was attached to an offset printing machine and printing was performed, a printed matter having good ink adhesion was obtained.
Distilled water was used as dampening water. When the inking property of the ink of the obtained printed matter was measured using a Coser reflection densitometer,
The inks using the new champion, cloth (ink) manufactured by Dainippon Ink and Neo Alpha Maxi, process (ink) manufactured by Dainippon Ink and Chemical Co., Ltd. were 0.9 and 1.0, respectively, and no background stain was observed. On the other hand, when the ink was printed using the same ink and the same fountain solution composition using a ps plate manufactured by a conventional method, the inking property of the ink was both 0.8, and the soiling property was recognized in some places.

Example 2 A high-density polyethylene film (number average molecular weight: about 100,000, thickness: about 150 microns) containing 50% by weight of magnesium hydroxide was set in a dry glass container, and the internal temperature was reduced to 0%.
か ら 5 ° C. externally, SO ₃ gas / nitrogen gas (volume ratio 1/2) was adjusted to 1 liter per minute, and the sulfonation reaction was conducted for 30 minutes while being introduced into the reaction vessel. Was done. After the reaction was completed, 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 was 14 degrees, the sulfonation amount was 1.5 × 10 ⁻⁴ meq / cm ² , and the absorbance ratio was 1.0. The film obtained in this manner is stuck on a rotating roll, and a helium / neon laser (NEC; GLG540) is used.
By scanning light condensed to a beam diameter of 20 μm (0, output 10 mW), a solid line and an image of a solid portion having a width of about 10 mm were formed. Next, this plate was attached to an offset printing machine and printing was performed in the same manner as in Example 1. As a result, an image and a solid printed matter having excellent ink adhesion were obtained. When the ink adhesion of the printed material was measured using a Coser reflection densitometer, the ink used was a new champion, cloth (ink) manufactured by Dainippon Ink and Neo Alpha Maxi, a process (ink) manufactured by Dainichi Seika. The ones used were 1.
0 and 1.2. No soiling was observed on the printed matter.

Example 3 From a copolymer of ethylene and ethyl acrylate containing 10% by weight of magnesium hydroxide (ethyl acrylate content 6.5 mol% at the start of polymerization, number average molecular weight about 30,000, crystallinity 65%) A film having a thickness of 150 μm was set in a dried glass container, and the operation was performed in the same manner as in Example 2 except that the reaction time was changed to 25 minutes to obtain a hydrophilic film. The contact angle of this film is 12 degrees and the sulfonation amount is
7.1 × 10 ⁻³ meq / cm ² , and the absorbance ratio was 0.9.

This film is attached to a rotating roll and a semiconductor laser (Sharp; LT027MD) is rotated while rotating at a speed of 2 m / sec.
/ MF, output 10 mW) was condensed by an optical lens and scanned to form a solid line and an image of a solid portion having a width of about 10 mm.

The printing plate thus obtained was attached to an offset printing machine, and printing was performed in the same manner as in Example 1 to obtain a printed material having excellent ink depositability. When the ink adhesion of the printed material was measured using a COSER reflection densitometer, Dainippon Ink Co., Ltd.'s new champion, cloth (ink) and Dainichi Seika's Neo Alpha Maxi, process (ink) were used. What was 1.0 and 1.0 respectively. No soiling was observed on the printed matter.

Example 4 A copolymer of ethylene and 4-methylpentene-1 containing 65% by weight of aluminum hydroxide (manufactured by Showa Light Metal Co., Ltd., Higlylite H-42) (content of 4-methylpentene-1 at the start of polymerization: 3 Mol%, number average molecular weight of about 30,000)
Sulfonation was performed under the same conditions as described above.

The film thus obtained had a contact angle of 11 degrees, a sulfonation amount of 1.6 × 10 ⁻⁴ meq / cm ² , and an absorbance ratio of 1.2.

 Next, a word processor (Sharp; Shoin)
, Model WD-300F) and print with a thermal head.
Was. The printing plate produced in this way is used for an offset printing press.
Attach and print by the same operation as in the first embodiment.
A printed material having excellent inking property was obtained. Ink of this printed matter
When the inking property was measured using a coser reflection densitometer,
The new champion of Dai Nippon Ink Co., Ltd.
Ross (Ink) and Neo-Alpha Maxi,
In the case of Roses (ink) ink, it is 1.3 and 1.2, respectively.
Was. No soiling was observed on the printed matter.

Example 5 Aluminum hydroxide was dried in a drying oven set at 300 ° C.
The treatment was performed for 0 minutes to obtain a composition having a composition of Al ₂ O ₃ · 2.3H ₂ O. Under the same conditions as in Example 2, a film having a thickness of about 200 microns made of a vinyl chloride resin (number average molecular weight of about 50,000) containing 30% by weight of the treated aluminum hydroxide was prepared.
The sulfonation reaction was performed for 0 minutes. The hydrophilic film thus obtained has a contact angle of 13 degrees and a sulfonation amount of 2.1 × 10
^-4 meq / cm ² , and the absorbance ratio was 0.7. A semiconductor laser (Sharp; LT027MD / MF, output 10mW) while attaching this film to a rotating roll and rotating at a speed of 2m / sec.
Is scanned while condensing it with an optical lens.
A solid image of mm was formed.

Next, the printing plate was attached to an offset printing machine and printing was performed in the same manner as in Example 1, thereby obtaining a printed material having excellent ink depositability. When the ink adhesion of the printed material was measured using a Coser reflection densitometer, the ink used was a new champion, cloth (ink) manufactured by Dainippon Ink and Neo Alpha Maxi, a process (ink) manufactured by Dainichi Seika. The ones used were 1.3 and 1.0, respectively. No soiling was observed on the printed matter.

Example 6 Aluminum hydroxide was dried in a drying furnace in the same manner as in Example 5.
After that, a composition having a composition of Al ₂ O ₃ .2.7H ₂ O was obtained. This treated high-density polyethylene film containing 50% by weight of aluminum hydroxide (number average molecular weight of about 5
(Thickness: about 150 μm) was set in a dried glass container, and the operation was performed in the same manner as in Example 2 except that the reaction time was set to 7 minutes to obtain a hydrophilic film. The contact angle of this film was 18 degrees, the sulfonation amount was 5.5 × 10 ⁻⁶ meq / cm ² , and the absorbance ratio was 0.9.

Next, the film was attached to a rotating roll, and a focused beam of a helium-neon laser (manufactured by NEC; GLG5400, output: 10 mW) was scanned to form a solid line and an image of a solid portion having a width of 10 mm.

The plate thus prepared was mounted on an offset printing machine in the same manner as in Example 1, and printing was performed. As a result, a printed material having excellent ink deposition was obtained. When the ink adhesion of the printed material was measured using a Coser reflection densitometer, the ink used was a new champion, cloth (ink) manufactured by Dainippon Ink and Neo Alpha Maxi, a process (ink) manufactured by Dainichi Seika. The ones used were 1.0 and 0.9, respectively. Almost no background stain was observed on the printed matter.

Comparative Example 1 A high-density polyethylene film (number average molecular weight: about 100,000, thickness: about 150 microns) containing 8% by weight of aluminum hydroxide was subjected to the same operation as in Example 2 to obtain a printing plate, and then offset printing was performed. Was. This printed matter was inferior in the inking property of the ink. When the ink adhesion of the printed material was measured using a Coser reflection densitometer, the ink used was a new champion, cloth (ink) manufactured by Dainippon Ink and Neo Alpha Maxi, a process (ink) manufactured by Dainichi Seika. The ones used were 0.8 and 0.6, respectively. In addition, background stains were observed in some places on the printed matter.

Comparative Example 2 A film was attempted after kneading 71% by weight of magnesium hydroxide and high-density polyethylene (number average molecular weight: about 50,000) using a Banbury mixer, but it was difficult to obtain a uniform film. 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 non-crystalline polymer compound, was sulfonated under the same conditions as in Example 2 with 23% by weight of magnesium hydroxide. After that, an image was formed on the surface, but no image formation was observed. When offset printing was performed in the same manner as in Example 1, no image reproduction was recognized, and ink adhered to the entire surface of the printed matter.

〔The invention's effect〕

According to the present invention, an offset printed matter which can simplify the steps of development and fixing, and is excellent in the inking property and background stain of the ink is provided, and its industrial effect is great.

Claims (1)

(57) [Claims] 1. A sulfonated film or sheet mainly comprising a filler composed of a polymer of an ethylene-based monomer and a metal hydroxide having a higher ionization tendency than hydrogen in an ionization column, and a red color on the sulfonated surface. In the external absorption spectrum, the ratio between the absorbance of the strong band near the wave number of 1200 and the absorbance of the band attributed to the sulfonic acid group near the wave number of 1050 is at least 0.6, using a modulated laser beam or a thermal head. An offset printing plate capable of forming a lipophilic image area on the surface by scanning.