JPS61192598A - Base material for planographic printing plate - Google Patents

Abstract

PURPOSE:To eliminate the generation of curling and to attain to enhance printing durability and printability, by laminating a metal foil to a sheet comprising a specific modified polyolefin composite material. CONSTITUTION:A metal foil with a thickness of 5-100mum is laminated to both surfaces of a sheet with a thickness 30-400mum obtained by forming a modified polyolefin composite material into a sheet. The modified polyolefin composite material is formed of 100pts.wt. of a modified polyolefin resin graft-modified by an org. silane compound and 150pts.wt. of mica. As the polyolefin resin used in order to obtain the above-mentioned modified polyolefin resin, a polypropylene resin is pref. As a metal foil, an aluminum foil is suitably used in both surfaces and a hard aluminum foil with elongation of 3% or less is especially pref. A photosensitive resin layer is provided to the surfaces of the metal foils laminated to both surfaces of the sheet (resin sheet) obtained by forming the above-mentioned composite material into a sheet is provided and the resulting product is used as a planographic printing plate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a substrate for a lithographic printing plate having excellent printability and printing durability.

[Conventional technology]

Generally, metals such as evaporated aluminum and stainless steel sheets are used as substrates for lithographic printing plates.

However, base materials for lithographic printing plates made of a single metal are heavy, have poor workability, and are expensive.

Therefore, a printing plate structure was proposed in which an aluminum sheet (foil) was bonded to one side of a thermoplastic resin sheet (Japanese Patent Publication No. 41362/1983).

[Problem that the invention seeks to solve]

However, with two single-sided metal foil laminated sheets, the base material curls,
Printing plates using this sheet have poor printing durability and printing suitability, making it unsuitable as a printing substrate.

Therefore, in order to suppress the curling of this single-sided metal foil laminated sheet, a base material for lithographic printing plates was proposed that uses a thermoplastic resin sheet made of a mixture of polyolefin resin and an inorganic filler. .

However, this substrate for lithographic printing plates also has problems with the printing durability of printing plates using this sheet, especially in heavy printing (printing tens of thousands of sheets or more).
For example, there is a problem that printing durability is poor in multi-color printing, and its uses are limited.

The present inventors completed the present invention as a result of intensive research to provide a base material for a lithographic printing plate that combines a thermoplastic resin sheet and a metal foil and does not have the above-mentioned problems.

[Failure to solve the problem]

That is, the present invention provides a sheet having a thickness of 30 to 40 mm obtained by forming a modified polyolefin composite material consisting of 100 parts by weight of a modified polyolefin resin partially or wholly graft-modified with an organic silane compound and 5 to 150 parts by weight of mica.
The present invention relates to a base material for a lithographic printing plate, which is formed by laminating metal foil with a thickness of 5 to 100 μm on both sides of a 0 μm sheet.

In the present invention, as a resin sheet to be laminated with metal foil, 100 parts by weight of a modified polyolefin resin partially or entirely graft-modified with an organic silane compound and 5 to 15 parts by weight of mica are used.
By using a sheet with a thickness of 30 to 400μ obtained by sheeting a modified polyolefin composite material consisting of 0 parts by weight, the substrate for lithographic printing plates does not curl, and printing durability and printability are improved. be able to.

The polyolefin resin used to obtain the above-mentioned modified polyolefin resin includes a crystalline homopolymer of propylene, propylene and ethylene, or other α-olefins (e.g., ptentopentene, hexene, heptene, octene-1, etc.). ) and polypropylene resins such as crystalline random or block copolymers of propylene, ethylene, and other α-olefins, and ethylene homopolymers and ethylene with a density of 0.93y/- or more. Examples include copolymers of and α-olefin, with polypropylene resin being preferred. Melt flow rate index (MFR) of polyolefin resin
is preferably 0.1 to 100y/10 minutes.

The organic sila/compounds include vinyltriethoxysilane, methacryloyloxytrimethoxysilane, γ-
methacryloyloxypropyltrimethoxysilane, methacryloyloxycyclohexyltrimethoxysilane, r-methacryloyloxypropyltriacetyloxysilane, methacryloyloxytriethoxysilane,
Examples include r-methacryloyloxypropyltriethoxysilane. These organic silane compounds may be used alone or in combination of two or more.

The modified polyolefin resin used in the present invention is
It is obtained by grafting at least a portion of the polyolefin resin and an organic silane compound, preferably in the presence of an organic peroxide.

The above-mentioned organic peroxide has a 1-minute half-life temperature of about 16
Preferably, those having a temperature of 0 to 260°C are used, such as tert-butyl peroxyisopropyl carbonate, di-tert-butyl peroxyphthalate, tert-butyl peroxyacetate), 2.5-
Dimethyl-2,5-di(tert-butylperoxy)hexane 22,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-6, tert-butylperoxylaurate, tert-butylperoxy Maleic acid, tert-butyl peroxybenzoate, methyl ethyl ketone peroxide, dicumyl peroxide, cyclohexanone peroxide, tert-butyl cumyl peroxide, 2
, 5-dimethylhexane, 2,5-sibide lobar oxide, and the like.

These organic peroxides may be used alone or in combination of two or more.

The modified polyolefin resin preferably contains 0.01 to 5 parts by weight of an organosilane compound per 100 parts by weight of the polyolefin resin, especially polypropylene resin.

In particular, 0.05 to 3 parts by weight and 0.01 to 5 parts by weight of organic peroxide.
parts by weight, especially 0.05 to 2 parts by weight, and the resulting mixture is heated to 160 to 270°C, especially 180 to 270°C.
It can be obtained by grafting by heating to a temperature of . The simplest heat treatment operation is to melt and heat the mixture in an extruder at the above temperature for about 1 to 10 minutes.

Particularly preferred is modified polyoleft-modified polyolefin, which is then crosslinked with water (including water vapor) and has an MFR of 10 to 80 f/10 minutes. The water crosslinking (including water vapor crosslinking) is performed in an atmosphere containing water vapor (or in the air).
This is suitably achieved by contacting the modified polypropylene resin with water vapor at 25 to 120°C for 1 hour or more, particularly 24 hours or more. In the present invention, the modified polyolefin citrus resin is used alone or more preferably in combination with a modified polyolefin resin and an unmodified polyolefin resin (MFRo, preferably 1 to 10 p/10 minutes).
And.

used in combination. When used in combination.

It is preferable to mix the modified polyolefin resin in a ratio of 5 to 150 parts by weight with respect to 100 parts by weight of the unmodified polyolefin resin. Part or all of the thus obtained polyolefin resin is graft-modified with an organic silane compound. Modified polyolefin resin has MFR from the viewpoint of sheet formability and physical properties.
is 0.3 to 80 g/10 min, especially 0.3 to 10 f/10
Preferably, it is minutes.

In the present invention, mica is used as an inorganic filler. Examples of mica include muscovite, phlogopite, biotite, and synthetic mica containing fluorine. A part of the mica may be replaced with another scaly filler. Mica has an average diameter (N amount average flake diameter) of 10 to 280μ, and an average aspect ratio (weight average aspect ratio) of 15
It is preferable that the diameter of 600 μm or more is 2% by weight or less. Mica may be surface treated with a surface treatment agent known per se, such as aminosilane. The blending amount of mica is 5 to 150 parts by weight, preferably 10 to 150 parts by weight, based on 100 parts of modified polyolefin resin which is partially or wholly graft-modified with a silane compound.
Parts by weight, particularly preferably 20 to 100 parts by weight. If the amount of mica incorporated is less than 5 parts by weight, the effect of improving the printing durability of the lithographic printing plate substrate is small, and if it exceeds 150 parts by weight, the printing durability will decrease.

The base material for a lithographic printing plate of the present invention is 1, for example, the above-mentioned modified polyolefin resin, or a modified polyolefin composite material obtained by heating and mixing a modified polyolefin resin, an unmodified polyolefin resin, and mica (when the polyolefin resin and mica are mixed, the polyolefin resin may be graft-modified with a silane compound) into a sheet. thickness 10
~400μ, preferably 100 to 280μ, on both sides of the sheet, either directly or via an adhesive, to a thickness of 5 to 100μ.

It is preferably obtained by laminating metal foils of 10 to 50 microns. The thickness of the laminated base material is 100 to 500 mm.
μ and 1rr? The fio is preferably 6 to 9 or less.

As the metal foil, aluminum foil is preferably used on both sides. In particular, hard aluminum foil with an elongation rate of 3 inches or less is preferably used.

The above-mentioned adhesive may be a solution type, an emulsion type, or a hot melt type. For example, epoxy resin, chlorinated polypropylene, polyurethane, modified polyolefin resin, ethylene-vinyl acetate copolymer, ionomer resin,
Examples include epoxidized 1,2-polybutadiene.

In the present invention, a photosensitive resin layer is provided on at least one side of metal foil laminated on both sides of a sheet (resin sheet) obtained by forming the composite material into a sheet, and the sheet is used as a lithographic printing plate (printing plate).

When laminating these metal foils, after laminating them, the surface is polished (sanded) and other treatments are applied, and a photosensitive resin is applied to create a lithographic printing plate (printing plate), or the surface of the metal foil is polished. (Sand) Sharpening.

In some cases, a lithographic printing plate is made by pre-processing such as anodizing or various hydrophilic treatments, then laminating and applying a photosensitive resin, or (sand) pre-processing after graining to make the plate photosensitive. You can make a lithographic printing plate by applying resin and then laminating them, or you can do pre-treatment (sanding), apply photosensitive resin, cut them to an appropriate size, and then laminate them after the plate-making process. Either method is possible, such as making a lithographic printing plate.

The method for laminating metal foil on both sides of a resin sheet is to first apply adhesive to one side of the metal foil or resin sheet,
A two-step roll method in which three layers of metal foil/adhesive/resin sheet are passed through a pressure roller and then another metal foil is similarly laminated on the resin sheet surface of the three-layer sheet, or each layer is laminated at once. One example is a one-stage roll method in which layers are laminated.

The lithographic printing plate substrate of the present invention is resistant to curling and has substantially the same performance as a single metal substrate, is lightweight and has excellent workability.

〔Example〕

Parts in the description below indicate parts by weight.

Example 1 After adding and mixing 0.5 part of γ-methacryloyloxypropyltrimethoxysilane and 0.25 part of t-butylperoxybenzony to 100 parts of a crystalline polypropylene homopolymer with an MFR of 9.0 f/10 minutes, Pellets (2
maJi! 'X3m) 14 parts and 56 parts of pellets (2mj2'X3m+) of crystalline polyglobylene homopolymer (MFRo, sf/1o min) (in addition, 0.
1 phr + 0.1 phr + rganox 1010
Calcium stearate was added to give a concentration of 0.2 phr), and mica [Susolite mica manufactured by Kuraray, phlogopite 325HK, average diameter 20μ.

Average aspect ratio of 20 to 25,100μ or more is 1
Weight% or less] 30 parts and 20 parts by Kobe Steel's FCM
A composite material was obtained by uniformly mixing at 0°C.

This material was formed into a sheet using a sheet molding machine (NRM) manufactured by Mitsubishi Heavy Industries ■ at a molding temperature of 200°C.

A sheet with a thickness of 240 μm and a width of 1 m was obtained. This sheet is
Tensile strength is 3.9 bKg/-(MD), 3.8
2/j (T D ), elongation 10% (MD), 4
% (TD), tensile modulus is 3109/mj (MD).

It was 29'1 ri/mj (TD).

Using urethane adhesive on both sides of this sheet, 30μ thick aluminum foil (elongation rate 2.0 inches, hard lN
30H) using the roll method with adhesive 5y/rr?・・・
・Front side, 1ay/rr? ...back side).

A double-sided aluminum foil laminated sheet with a thickness of about 300μ was obtained (13o, lt'sKp/m"). No curling was observed in this sheet.

This laminated sheet (cut into 560 pieces x 670 pieces).

Approximately 0μ5Kg/m'') was evaluated as a substrate for lithographic printing plates by the following method.

Evaluation method: Process the front (mirror side) aluminum surface of the laminated sheet using an abrasive with an appropriate grain size in a grain chamber (surface grain size: approx. 1.5
μ) and after hydrophilic treatment, a commercially available photosensitive resin was applied to prepare a lithographic printing plate.

This lithographic printing plate was subjected to a printing durability test using an offset printing machine under the following conditions.

1. Plate making (1) Exposure: Ultra-high pressure mercury lamp 2KW (11) Development: Sakura PS version automatic developing machine 860A.

Developer Sakushi 5DP-1 2 Printing machine test method (1) Printing machine; Offset printing machine made by Ryobi 480 Ink; Process 4 colors of red, yellow, blue, and black (11) Printing speed: 10000 rpm Shadow of printed matter Department and No.
Printing durability was evaluated based on changes in the dot area and dot density in the illite area, as well as changes in reflection density in the gray scale area.

From printing to printing 5oooo sheets, thinning of halftone dots 2
No development such as a decrease in ink adhesion in the image area was observed, and good printability was maintained.

In addition, during printing, the defective rate due to breakage at the gripping portion when the printing plate was attached to the printing roll was 0 (tested for 5 sheets).

Example 2 The blending ratio of each component was changed to modified polypropylene (MFR50
710 minutes), 36 parts of crystalline polypropylene homopolymer (MFRo, 5f/10 minutes), and mica (
A composite material was obtained in the same manner as in Example 1 except that the amount was changed to 50 parts (325HK).

Using this composite material, approximately (M D
), '5-94Kg/rttiA (T D ), elongation is 5 inches (MD), 3 inches (TD), tensile modulus is 425
Then, a lithographic printing plate was obtained in the same manner.

A printing durability test was conducted on this lithographic printing plate in the same manner as in Example 1, and it was found that from the start of printing to the printing of 500 sheets, there were no signs of development, such as a decrease in ink receptivity in the fine halftone dot 2 image area. is not recognized at all.

Good printability was maintained.

In addition, the defect rate due to breakage at the gripping part during printing is 0% (
5 sheets were tested).

Comparative Example 1 Crystalline polypropylene homopolymer was used as a composite material, and aluminum foil with a thickness of 30 μm was rolled on one side of a sheet with a thickness of 270 μm obtained by forming the same into a sheet using a urethane adhesive as an adhesive. A single-sided aluminum foil laminated sheet with a thickness of about 300 μm was obtained by laminating the aluminum foil by the method.

This laminated sheet curled significantly and was unsuitable as a printing substrate, so the printing durability test was discontinued.

Comparative Example 2 Using a crystalline polypropylene homoboline adhesive as a composite material, aluminum foils with a thickness of 30μ were laminated by a roll method to obtain a double-sided aluminum foil laminated sheet with a thickness of about 300μ, and then a lithographic printing plate was obtained. Ta.

A printing durability test was conducted on this lithographic printing plate.

Local thinning of the halftone dots was observed from the time of printing.

There was a problem with printing durability.

Example 3.4.5 As the mica, 3258 (■ manufactured by Kuraray, average diameter 40 μm) was used instead of 325HK (stripite mica).

1% by weight of items with an average aspect ratio of 30,210μ or more
Below] (Example 3), 325 to -1 (■ Kuraray, 32
58 aminosilane surface treatment grade] (Example 4),
The same procedure as in Example 1 was carried out except that 350-1 [: Kuraray g, 325HK aminosilane surface treatment grade] (Example 5) was used. Good results equivalent to those of Example 1 were obtained in all cases.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain a base material for a lithographic printing plate that is lightweight, easy to handle, and provides a lithographic printing plate having excellent printability and printing durability.

Claims (5)

[Claims] (1) 100 parts by weight of a modified polyolefin resin partially or wholly modified with an organic silane compound and mica 5
A base material for a lithographic printing plate, comprising a sheet having a thickness of 30 to 400 .mu.m obtained by sheeting a modified polyolefin composite material comprising 150 parts by weight, and a metal foil having a thickness of 5 to 100 .mu.m laminated on both sides of the sheet. (2) The substrate for a lithographic printing plate according to claim 1, wherein the modified polyolefin resin is a modified polypropylene resin. (3) The substrate for a lithographic printing plate according to claim 1, wherein the metal foil is an aluminum foil. (4) The substrate for a lithographic printing plate according to claim 1, wherein the mica has an average diameter of 10 to 280 μm and an average aspect ratio (average diameter/average thickness) of 15 to 70. (5) The substrate for a lithographic printing plate according to claim 1, wherein the aluminum foil has a tensile elongation rate of 3% or less.