JPH10100362A - Thermal mode recording material and production of driographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal mode recording material for producing a driographic printing plate of high quality not too much generating blocking. SOLUTION: This thermal mode recording material is obtained by forming a recording layer containing a light-heat conversion substance capable of converting radiant light to heat and an oleo-phobic surface layer on a flexible support having an oleophilic surface and, herein, the oleophobic surface layer and the recording layer can be the same layer. The coefficient of dynamic friction (μk) at a time when one side of the material slides on the other side thereof is 2.6 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[1. FIELD OF THE INVENTION The present invention relates to a thermal mode recording material for preparing a lithographic printing plate for use in fountainless lithographic printing. The invention further relates to a method for imaging the thermal mode recording material with a laser.

[0002]

[2. BACKGROUND OF THE INVENTION Lithographic printing involves the use of a specially prepared surface from a specially prepared surface where some areas of the surface can accept ink (oleophilic areas) while others do not. The printing method. The oleophilic area forms the printing area, while the oleophobic area forms the background area.

[0003] Two basic types of lithographic printing plates are known. According to a first type, the so-called wet printing plate, both water or an aqueous dampening solution and ink are applied to the printing plate surface containing hydrophilic and hydrophobic areas. The hydrophilic areas are moistened with water or dampening liquid, thereby rendering them oleophobic, whereas the hydrophobic areas receive ink. A second type of lithographic printing plate is operated without the use of a dampening solution and is driographic.
called a printing plate. This type of printing plate contains areas of high ink repellency and lipophilic areas. Generally, the high ink repellent area is formed by a silicon layer.

[0004] Drographic printing plates can be made using photographic materials that are made image-receptive or repellent to the ink upon exposure of the material. However, thermal mode recording materials whose surface can be made image-wise receptive or repellent to the ink upon image-wise exposure to heat and / or subsequent development, also have implications for making driographic printing plates. Is known.

[0005] For example, DE-A-2512038 discloses that on a support bearing or having a lipophilic surface,
(I) a thermal mode recording layer containing a self-oxidizing binder such as nitrocellulose and a substance capable of converting radiation into heat, for example, carbon black;
i) A thermal mode recording material comprising a non-hardened silicon layer as a surface layer is disclosed. The disclosed thermal mode recording material is image-wise exposed using a laser and subsequently developed using a developer capable of dissolving the silicon layer in the exposed areas. Following this development, the silicon surface layer is hardened. This method is ecologically disadvantageous because naphtha is used as developer. Furthermore, since the surface layer is not hardened, the thermal mode recording material can be easily damaged during handling.

[0006] FR-A-1.473.751 discloses a thermal mode recording material comprising a substrate having a lipophilic surface, a layer containing nitrocellulose and carbon black and a silicon layer. After image-wise exposure with a laser, the imaged area is said to be lipophilic. The decomposed silicon layer is not removed. The printing plate obtained has a low ink acceptability and has somewhat poor printability such as print durability and copy resolution.

Research Di of April 1980
Closure 19201 discloses a thermal mode recording material including a polyester film support having a bismuth layer as a thermal mode recording layer and a silicon layer provided thereon. The disclosed thermal mode recording material is imaged with an argon laser and developed with hexane.

EP-A-573091 discloses a recording layer on a support having a lipophilic surface, comprising (i) a layer having a thickness of 3 μm or less and containing a substance capable of converting laser beam radiation into heat. And (ii) a method of making a lithographic printing plate comprising a hardened oleophobic surface layer, wherein the recording layer and the oleophobic surface layer require a thermal mode recording material that can be the same layer. ing.

As described above, it can be seen that a plurality of proposals for producing a driographic printing plate using a thermal mode recording material have been made. All these printing plates have the disadvantage that they cause blocking. This creates difficulties at all stages in which the material is transported, such as winding up during secondary processing, format cutting and packaging, automatic loading on the press, transport through irradiation stations, and the like.

[0010]

[3. SUMMARY OF THE INVENTION In accordance with the present invention, an object is to provide an alternative thermal mode recording material for making a high quality driographic printing plate that causes less blocking.

It is a further object of the present invention to provide a method for obtaining a high quality driographic printing plate using a thermal mode recording material which does not cause much blocking.

Further objects of the present invention will become clear from the description hereinafter.

According to the present invention, (i) a recording layer containing a light-to-heat converting substance capable of converting radiation to heat, and (ii) a flexible layer having a lipophilic surface.
A thermal mode recording material comprising an oleophobic surface layer, wherein the oleophobic surface layer and the recording layer can be the same layer, wherein one side of the material slides on the other side of the material Wherein the coefficient of dynamic friction (μ _k ) of the material is 2.6 or less.

According to the invention, it is also provided that:-the thermal mode recording material described above is image-wise exposed using a laser beam;-the exposed thermal mode recording material is developed, whereby the exposed area of the material is exposed. Also provided is a method of making a lithographic printing plate that does not require a dampening solution, comprising removing the oleophobic surface layer to expose the underlying lipophilic layer.

[0015]

[4. DETAILED DESCRIPTION OF THE INVENTION The above thermal mode recording material comprises:
It has been found that when the kinetic coefficient of friction is less than 2.6, it exhibits reduced blocking, which leads to easier production and use of the material and an improved printing plate with regard to its physical properties (less wrinkles). .

The coefficient of kinetic friction (μ _k ) is standard ASTM D1
Measured according to 894, whereby the thermal mode recording material is placed such that the backside of the underlying material is in contact with the front side of the overlying material. The backside of the material refers to the side of the material without the oleophobic surface layer on the flexible support, and the front side refers to the side of the material with the oleophobic surface layer on the flexible support. .

The coefficient of dynamic friction (μ _k ) is preferably 1.25 or less. The lower limit is as low as possible, but is preferably at least 0.05, more preferably at least 0.10.

To reduce the coefficient of kinetic friction, the flexible support of the thermal mode recording material is treated with a backside coating or a matting agent is added to the oleophobic surface layer, or both methods are used together.

A preferred backside coating according to the present invention is 175-750 mg / m ² gelatin, 50-10
At least 100 m ² / g 200 mg / m ^2, more preferably colloidal silica with a surface area of at least 300 meters ² / gram, and preferably 1 to 100 mg / m ² containing amorphous silica having a 1~10μm diameter .

Another preferred backside coating according to the present invention is a 100-500 mg / m ² polymethyl-methacrylate latex, preferably having a particle size of 25-300 n
m), colloidal silica having a surface area of at least 100 m ² / gram 5~50mg / m ^2, 3~30mg / m
² , polyethylene wax of 3.1 to 12 mg / m ² of polystyrene sulfonic acid, 0.9 to 4 mg / m ² of poly (3,4-ethylenedioxy-thiophene) and
It contains 100 mg / m ² of a polymethyl-methacrylate matting agent (preferably having a diameter of 2 to 10 μm).

[0021] Yet another preferred backside coating according to the present invention, PVA, comprises TiO ₂ and hydrolyzed tetraalkyl orthosilicate, wherein SiO ₂ constitutes 7 to 30 wt% of the total weight of said matrix, TiO
₂ comprises 63-83% by weight of the total weight of the matrix, and PVA makes up 7-30% by weight of the total weight of the matrix. The total weight of the matrix is 5-10
g / m ² . 3 to 500 mg in the matrix
Matting agents such as starch, silicon oxide, silicates, glass particles, toner particles can be added in an amount of / m ² .

The matting agent added to the oleophobic surface layer to reduce the coefficient of kinetic friction is an organic polymer or copolymer, such as a copolymer of acrylic acid and methyl acrylate, or a copolymer of styrene, methyl-methacrylate and maleic acid. Can be. More preferably, the matting agent is an inorganic compound, such as silica or silicate.

The matting agent is at least 2 μm, more preferably at least 3 μm, most preferably at least 4 μm.
It has a weight average diameter of μm. The maximum weight average is not critical, but for practical reasons is less than 100 μm, more preferably less than 60 μm.

According to the invention, the oleophobic surface layer preferably has a weight-average diameter of at least 2 μm, at least 30 mg / m ² of matting agent, more preferably 50 to 1
000 mg / m ² of the matting agent, most preferably 75 to
Contains 500 mg / m ² of the matting agent.

Suitable flexible supports for the thermal mode recording material used according to the present invention can be transparent or opaque, for example a paper support or a resin support. If a paper support is used, preference is given to one or both sides coated with an alpha-olefin polymer, for example a polyethylene layer, which can optionally contain antihalation dyes or pigments. Organic resin supports such as cellulose nitrate film, cellulose acetate film, poly (vinyl acetate) film, polystyrene film, poly (ethylene terephthalate) film, poly (ethylene naphthalenedicarboxylate) film, polycarbonate film, polyvinyl chloride film or poly -Alpha-olefin films, for example polyethylene or polypropylene films, can also be used. The thickness of such an organic resin film is 0.
It is preferably included in the range of 06 to 0.35 nm. These organic resin supports are preferably coated with a lipophilic adhesive layer.

According to a preferred embodiment of the present invention, the thermal mode recording material may contain a separate thermal mode recording layer containing a heat converting substance between the support and the oleophobic surface layer. Examples of substances capable of converting radiation into heat are, for example, carbon black, infrared or near infrared absorbing dyes or pigments, metals such as Bi, Sn, Te, or combinations thereof. Suitable infrared dyes are, for example, US-4833124, EP-321923, US-4.
775883, US-4942141, US-4948
776, US-4948777, US-494877
8, U.S. Pat. No. 4,950,639, U.S. Pat. No. 4,950,640, U
S-4912083, US-495552, US-5
024990, US Pat. No. 5,023,229. Suitable infrared pigments are, for example, Heubach La
HEUCODER metal oxide pigment available from Ngelsheim. When a metal such as bismuth is used as the heat conversion material, the recording layer is preferably a vacuum-deposited metal layer.

According to the present invention, the thickness of the recording layer is preferably 3 μm or less, and more preferably less than 2.5 μm, to obtain a printing plate of acceptable quality. Typically, the recording layer preferably has a thickness of 15 nm to 1.5 μm. The preferred maximum thickness of the recording layer of 3 μm is particularly important when the exposure is performed through a support.

According to a particular embodiment of the present invention, the recording layer can be a vacuum-deposited aluminum layer.
However, the thickness of such an aluminum layer must be less than 25 nm, more preferably between 10 nm and 22.5 nm. If the thickness of the aluminum recording layer becomes too thick,
The thermal mode recording material associated with the present invention cannot be imaged.

The thermal mode recording layer used in connection with the present invention comprises a binder such as gelatin, cellulose, cellulose esters such as cellulose acetate, nitrocellulose, polyvinyl alcohol, polyvinylpyrrolidone, a copolymer of vinylidene chloride and acrylonitrile, It may contain (meth) acrylate, polyvinyl chloride, silicone resin, and the like. The recording layer can further contain other components such as wetting agents, matting agents, antioxidants and the like. The thermal mode recording layer preferably contains a polymer containing covalently bonded chlorine. Alternatively, some or all of the polymer may be contained adjacent to the thermal mode recording layer, most preferably in a separate layer located between the support and the thermal mode recording layer.

[0030] The thermal mode recording layer associated with the present invention can be hardened. For example, a nitrocellulose layer hardened with isocyanate or melamine can be used.

It has been found that the speed of the recording material can be increased if the polymer containing covalent chlorine is contained in the thermal mode recording layer or an adjacent layer of the recording material.

Chlorine-containing polymers suitable for use in accordance with the present invention include, for example, polyvinyl chloride, polyvinylidene chloride, vinylidene chloride, copolymers of acrylic esters and itaconic acid, copolymers of vinyl chloride and vinylidene chloride, vinyl chloride and vinyl acetate. Copolymers, butyl acrylate, vinyl acetate and vinyl chloride or vinylidene chloride copolymers, vinyl chloride, vinylidene chloride and itaconic acid copolymers, vinyl chloride, vinyl acetate and vinyl alcohol copolymers, chlorinated polyethylene, polychloroprene and their copolymers, chloro Sulfonated polyethylene, polychlorotrifluoroethylene, polymethyl-alpha-chloroacrylate and the like.

The chlorine-containing polymer used in connection with the present invention can be produced by various polymerization methods of the constituent monomers. For example, the polymerization can be carried out in an aqueous dispersion containing a catalyst and an activator, such as sodium persulfate and sodium metabisulfite, and an emulsifier and / or dispersant. Alternatively, homopolymers or copolymers for use with the present invention can be prepared by polymerizing the monomer components in bulk without the addition of a diluent, or the monomers are reacted in a suitable organic solvent reaction medium. be able to. The total catalyst-activator concentration should generally be kept in the range of about 0.01% to about 2.0% by weight of the monomer charge, with a concentration in the range of 0.1% to 1.0%. preferable. Improved solubility and viscosity values can be obtained by conducting the polymerization in the presence of mercaptans, such as ethyl mercaptan, lauryl mercaptan, tertiary dodecyl mercaptan, which are effective in reducing crosslinking of the copolymer. In general, the mercaptans should be used at a concentration of 0.1% to 5.0% by weight, based on the weight of polymerizable monomers present in the charge.

In another case, a chlorine-containing polymer can be produced by chlorinating a homopolymer or copolymer. For example, chlorinated rubber such as polychloroprene can be produced by reacting rubber with chlorine gas. Chlorinated polyethylene can be produced in a similar manner.

According to another embodiment, a heat conversion material can be included in the oleophobic surface layer, provided that the material is uniformly distributed there.

The oleophobic surface layer according to the invention is preferably at least 1.0 μm, more preferably at least 1.
It has a thickness of 5 μm. The maximum thickness of the surface layer is not critical, but is preferably 5 μm or less, more preferably 4 μm or less. It has been found that the thickness of the oleophobic surface layer affects the printing durability, sharpness and resolution of the printing plate.

According to the present invention, the oleophobic surface layer is preferably hardened and more preferably contains a hardened silicon coating. Silicon coatings comprise one or more components, one of which is generally a linear silicone polymer terminated at both ends with chemically reactive groups, as well as a multifunctional component as a hardener. Is preferable. The silicon coating can be hardened by condensation hardening, additional hardening or radiation hardening.

Condensation hardening can be carried out by using a hydroxy-terminated polysiloxane which can be hardened with a polyfunctional silane. Suitable silanes are, for example, acetoxysilanes, alkoxysilanes and silanes containing oxime functionality. In general, condensation hardening is carried out in the presence of one or more catalysts, for example tin salts or titanium salts. Alternatively, the hydroxy-terminated polysiloxane can be hardened with a polyhydrosiloxane polymer in the presence of a catalyst, for example, dibutyltin diacetate.

Addition hardening is based on the addition of Si-H to double bonds in the presence of a catalyst such as, for example, platinum. Silicone coatings which can thus be hardened according to the addition hardening include vinyl group-containing polymers, for example catalysts such as chloroplatinic acid complexes and polyhydrosiloxanes such as polymethylhydrosiloxane. Suitable vinyl-containing polymers are, for example, vinyldimethyl-terminated polydimethylsiloxane and dimethylsiloxane / vinylmethylsiloxane copolymer.

Radiation-hardening coatings which can be used according to the invention include, for example, U.S. Pat. V. A hardenable coating or an electron beam hardenable coating containing a polysiloxane polymer containing (meth) acrylate groups. The latter coating preferably also contains a multifunctional (meth) acrylate monomer.

According to the present invention, the ink repellent layer can include additional substances, such as plasticizers, pigments, dyes, and the like.

According to the method of the present invention, the thermal mode recording material is image-wise exposed using a laser. Lasers preferably used are, for example, semiconductor lasers, YA
G laser, for example, Nd-YAG laser, argon laser and the like. The latter can have a power of 35-20,000 mW and preferably work in the infrared part of the spectrum. The support of the thermal mode recording material is transparent,
Preferably, image-wise exposure is carried out via the support.

Following image-wise exposure, the thermal mode recording element is developed to remove the oleophobic surface layer in the illuminated areas. Preferably, the development is performed by rubbing the oleophobic surface layer. For example, it can be rubbed using a brush or a cotton pad. If the surface layer contains a polysiloxane, the thermal mode recording material can be rubbed in the presence of a solvent such as, for example, isopropanol, n-heptane or other hydrocarbon liquid, or rubbed in the absence of a liquid. More preferred. Scoring according to a preferred embodiment provides, besides ecological advantages, a printing plate of high resolution and sharpness.

The present invention will now be described with reference to the following examples, but the present invention is not limited to the examples. All parts are by weight unless otherwise specified.

[0045]

【Example】

Example 1 The following coating solution for the ink repellent layer was prepared: iso-octane up to 1000 ml divinyl-terminated dimethylpolysiloxane 59.5 g dimethylpolysiloxane rubber 28.2 g platinum divinyltetramethyldisiloxane complex 0.37 g hydride Terminated dimethylpolysiloxane (1.79 g DC 7048 crosslinker from Dow) Stabilizer (0.18 g Surfinol 61 from Air products) The following coating solution for the recording layer was prepared: ethyl acetate / butyl acetate (60: 40) Mix up to 1000 ml Spesial Schwarts (24.6 g carbon black from Degussa) Solsperse 28000 (wetting agent from ICI) 2.64 g Solsperse 500 (Wetting agent from ICI) 0.52 g (2.14 g melamine hardener from Dyno Cytec) Nitrocellulose 11.87 g Cymel 301 p-toluenesulfonic acid 0.42g polyethylene terephthalate film support (175Myu
m) the above coating solution for the recording layer;
Comparative thermal mode recording material A0 was prepared by coating with a wet coating thickness of 22 μm resulting in a dry layer thickness of 2 μm.

This layer was coated with an ink repellent layer from the above coating solution to a dry thickness of 3.42 μm. Subsequently, the ink repellent layer was hardened at 130 ° C. for 3 minutes.

The thermal mode recording material of the present invention is obtained by leaving the back side of the flexible support as it is to obtain the element An, or by coating the back side of the flexible support with the backside solution B to obtain the element Bn. Coating C to obtain element Cn, or coating backside solution D to obtain element Dn (where n represents an integer from 0 to 3), and / or further supplemented with a coating solution for the ink repellent layer To obtain element X0 without the agent, or to obtain element X1 containing 100 mg / m ² of matting agent 1, or 100 mg / m ²
To obtain the element X2 containing the matting agent 2 of
Manufactured in the same manner as the comparative sample, except that g / m ² of matting agent 3 is obtained to obtain element X3, where X represents A, B, C or D, these capital letters having the meanings given above.

The back coating B gelatin of 233 mg / m ^2, the surface area of the 520 mg / m ² is the diameter of the colloidal silica and 10 mg / m ² of 300 meters ² / gram containing amorphous silica 4 [mu] m.

Back coating C comprises PVA, TiO ₂ and hydrolyzed tetraalkyl orthosilicate, where SiO ₂ is 7.5% by weight of the total weight of the matrix
Configure, TiO ₂ is the total weight of the matrix 75
Wt%, and PVA makes up 17.5% by weight of the total weight of the matrix. The total weight of the matrix is in an amount of 6.8 g / m ² .

The back coating D was 200 mg / m ² of polymethyl-methacrylate latex (particle size: 25 to 3).
00 nm), 20 mg / m ² colloidal silica with a surface area of 100 m ² / gram, 10 mg / m ² polyethylene wax, 7 mg / m ² polystyrene sulfonic acid, 3 m
g / m ² of poly (3,4-ethylenedioxy-thiophene) and 30 mg / m ² of 6 μm diameter polymethyl-
Contains methacrylate matting agents.

Matting agent 1 is an amorphous silica having a weight average diameter of 4.3 to 5.3 μm and treated with an amide of a fatty acid (SYLOBLOC 250). Matting agent 2
Is a wax-treated amorphous silica having a weight average diameter of 4.3 to 4.9 μm (SYLOID 700
0). Matting agent 3 is an amorphous aluminosilicate having a weight average diameter of at most 40 μm (SYLOSI
VA3). SYLOLOC 250, SYLOID
GraceDe for 7000 and SYLOSIV A3
This is a trade name from Vison, Belgium.

The coefficient of kinetic friction (μ _k ) and the blocking of the resulting thermal mode recording material were measured. μ _k is ASTM
Measured according to D1894. Blocking was measured by visual inspection during film winding. Therefore 2
A film having a width of 4 cm is wound up at a speed of 7 m / min. The mechanism for manipulating the film winding is removed over 2 cm. The effect of this removal on the wound film is qualitatively assessed.

[0053]

[Table 1]

Guarantees up to a rating of 2 are acceptable; guarantees with a rating of 3 or more are no longer acceptable. The results for various thermal mode recording materials are shown in Table 1.

[0055]

[Table 2]

From these results, the thermal mode recording material A0 (comparative material) having a dynamic friction coefficient of 4.4 showed very strong blocking, but other thermal mode recording materials (materials of the present invention) were acceptable. It is clear that the obtained blocking or no blocking was demonstrated. Best results are obtained when a backing coating is used as well as a matting agent in the ink repellent layer.

The main features and aspects of the present invention are as follows.

1. A flexible support having a lipophilic surface, comprising: (i) a recording layer containing a light-to-heat conversion material capable of converting radiation to heat; and (ii) an oleophobic surface layer. The oleophobic surface layer and the recording layer are thermal mode recording materials that can be the same layer, wherein the coefficient of kinetic friction (μ _{k) of the} material as one side of the material slides on the other side of the material ) Is 2.6 or less.

2. 2. The thermal mode recording material according to the above item 1, wherein the dynamic friction coefficient is included in the range of 1.25 to 0.05.

3. 3. A thermal mode recording material according to claim 1 or 2, wherein said thermal mode recording material comprises a backside coating.

4. 4. The thermal mode recording material according to any one of the above items 1 to 3, wherein the matting agent is present in the oleophobic surface layer.

[0062] 5. -Imagewise exposing the thermal mode recording material according to any of the above items 1 to 4 using a laser beam;-developing the exposed thermal mode recording material and thereby the oleophobicity of the exposed areas. A method of making a lithographic printing plate that does not require a dampening solution, comprising the step of removing a surface layer to expose an underlying lipophilic layer.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Giyoan Vermeersch Belgium 2640 Malt Cell Septes Trat 27 Agfa-Gevuert na Mrose Fennoutjaps (72) Inventor Gene van Trier Belgium Bee 2640 Malt Cell Septest Trat 27Agfa-Gevert Na Mrose Rose

Claims (2)

[Claims] 1. On a flexible support having a lipophilic surface,
(I) a recording layer containing a light-to-heat conversion material capable of converting radiation into heat; and (ii) an oleophobic surface layer, wherein the oleophobic surface layer and the recording layer are the same layer. A thermal mode recording material, which can be one of said materials.
A thermal mode recording material characterized in that the material has a coefficient of dynamic friction (μ _k ) of 2.6 or less when one side slides on the other side of the material. 2. Exposing the thermal mode recording material according to claim 1 imagewise with a laser beam; developing the exposed thermal mode recording material, whereby the oleophobicity of the exposed areas A method of making a lithographic printing plate that does not require a dampening solution, comprising the step of removing a surface layer to expose an underlying lipophilic layer.