JPH0263051A - Light transparent film for coating image forming material - Google Patents

Abstract

PURPOSE:To improve the workability in an evacuation operation and to improve the adhesive property of a positive or negative film by incorporating particles having an average particle size and refractive index of prescribed values into the above film. CONSTITUTION:The light transparent film is preferably the film formed by applying a polymer soln. contg. the prescribed particles on the surface of a transparent plastic film, for example, transparent plastic film consisting of polyethylene terephthalate, etc., or the film formed by applying the polymer soln. contg. the prescribed particles directly on an image forming material to form a coating layer. Particularly, the former film is more preferable in terms of the evacuation operation efficiency, the stability of the resulted light transparent film, the workability, the ease of production, etc. The average particle size measured by coalter counter method is required to be 4 to 9mu and the refractive index of the particles is required to be 1.40 to 1.70, more preferably 1.40 to 1.60. The time required for the vacuum adhesion of the positive or negative film is shortened in this way and the workability of the printing plate is improved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a light-transmitting film for coating an image-forming material, which can significantly improve workability when exposing the image-forming material to form a latent image. .

[Prior Art] Conventionally, when an image forming material is exposed through a positive film or a negative film, a vacuuming operation is usually performed in order to obtain a good image without blurring. in this case,
In order to finish the vacuuming work in a short time, for example, as seen in Japanese Patent Publication No. 61-614, a coating layer with unevenness is laminated on the surface of the image forming material. No. 11673 proposes a method of forming an uneven surface or a covering layer. Special Public Service 1986-
According to 614, the average height difference of the uneven surface is 0.1 to 3μ.
Therefore, it is described that a solution containing inorganic particles with a diameter of 0.1 to 3 μm should be applied, and that if the difference in height exceeds 3 μm, it will be impossible to reproduce minute halftone dots.

[Problems to be Solved by the Invention] The coating layer proposed in the above-mentioned Japanese Patent Publication No. 61-614 can significantly improve the efficiency of vacuuming work compared to a coating layer with a smooth surface, but it is still insufficient. There was a need to develop a technology that could process the process in even shorter time.

The present invention was devised in view of the current state of the prior art, and its purpose is to significantly improve the workability of vacuuming work when exposing an image forming material to form a latent image, and to An object of the present invention is to provide a light-transmitting film for coating an image forming material, which has extremely good adhesion.

[Means for Solving the Problems] The object of the present invention is to provide particles having an average particle diameter of 4 to 9 μm as measured by the Coulter Counter method, and a refractive index of 1.
This is achieved by a light-transmitting film for coating an image forming material, which is characterized by containing particles having a particle diameter of 40 to 1.70.

The light-transmissive film for covering the image-forming material used in the present invention includes the following various embodiments.

(1) Known transparent plastic films, such as polyethylene terephthalate, polyvinylidene chloride, polyvinyl chloride, copolymers of vinyl chloride and vinylidene chloride, polyamide, polyurethane, cellophane, polyvinyl alcohol, polypropylene.

It is formed by applying a polymer solution containing specific particles to the surface of a transparent plastic film such as polyethylene, polystyrene, or cellulose acetate.

(2) A coating layer formed by applying a polymer solution containing predetermined particles directly onto an image forming material.

(3) A film formed by adding specified particles to a transparent plastic film.

Among these, those according to (1) or those formed by applying a polymer solution containing particles of (■) are preferable;
The former method is particularly preferable in terms of vacuum efficiency, stability of the resulting light-transmitting film, workability, and ease of production.

Examples of the polymer used when applying particles to the surface of the transparent plastic film or image-forming material, that is, the binder polymer, include the film-forming materials described in item (1) above.

The thickness of the transparent plastic film is preferably in the range of 0.1 to 20μ, more preferably 1 to 10μ. Furthermore, when a polymer solution containing particles is applied to the surface of an image forming material or a transparent plastic film, the dry thickness is preferably 10 g/% or less, more preferably 4 g/- or less. . The lower limit of the coating amount is not particularly limited, but from the viewpoint of coating properties, it is 0.
゜1g/rI? It is preferable that it is above.

The particles used in the present invention must have the following characteristics.

(1) The average particle diameter measured by Coulter Counter method is 4 to 9μ.

(2) The particles have a refractive index of 1.40 to 1.70, more preferably 1.40 to 1.60.

Examples of such particles include natural silica (Minex #7, Shiraishi Kogyo Co., Ltd.), calcium carbonate (Whiten P-30, Shiroishi Kogyo Co., Ltd.), synthetic silica (Thyroid 63, Fuji Davison Chemical Co., Ltd.). )), mica, cornstarch, epoxy particles, etc.

In the present invention, it is important to use particles having a refractive index and average particle size within a specific range, so that the refractive index of the film-forming material or binder polymer used is close to that of the particles. This made it possible to significantly improve the light transmittance of the light-transmitting film and to create unevenness with a large difference in height, thereby making it possible to significantly shorten the evacuation time. Note that the difference between the refractive index of the film-forming material or binder polymer and the refractive index of the particles is not particularly limited, but is preferably 0.3 or less.

Regarding the particle size distribution of the particles, from the viewpoint of processing efficiency of vacuuming work and reproducibility of minute halftone dots, particles of 2μ or less are preferable.
% or less, and the proportion of grains of 20μ or more is preferably 10% or less.

In addition, the amount of the particles added is 0°001 g/r from the viewpoint of processing efficiency of vacuuming work and reproducibility of minute halftone dots.
It is preferably from rr to 0.1 g/%, more preferably from 0.01 g/i to 0.1 g/M.

The light-transmissive film for covering an image forming material in the present invention is an image forming material that is exposed in close contact with a positive film or a negative film, such as a letterpress printing plate.

It can also be applied to lithographic printing plates, waterless lithographic plates, dry film resists, etc. Among them, waterless lithographic printing plates with a silicone rubber layer on the upper layer (for example,
923, Special Publication No. 56-23150, Special Publication No. 61-542
22, JP 59-28479, JP 60-2105
0. It can be suitably applied to Japanese Patent Application Laid-open No. 60229031, etc.).

The "Coulter-Counter method" used in the present invention refers to the method described on page 473 of "Powder Theory and Application" (published by Maruzen Co., Ltd. on April 20, 1960), a special edition by Kikubo Kubo. .

[Example] The present invention will be specifically explained below using Examples.

Example 1 Polyethylene terephthalate film with a thickness of 6.5μ
A coating solution having the following composition was applied to Lumirror (manufactured by Toshi ■) and dried at 100°C for 30 seconds.

(a) Polyurethane (Sunbren 5218 manufactured by Kosaku Kasei Co., Ltd.)
, refractive index 1.53) 100 parts by weight (b) Thyroid 63 (manufactured by Fuji Davison, average particle diameter 6 μ by Coulter-Counter method, 10% by weight or less of 2 μ or less and 20 μ or more, refractive index 1.46)
8 parts by weight (C) dimethylformamide 4
77 parts by weight (d) 477 parts by weight of methyl ethyl ketone The thickness of the coated layer after drying was Ig/%, and the amount of particles added was 0.07 g/rrr. The smoothness of this film was measured using an Oken type air permeability and smoothness tester (manufactured by Keiken Kenkyu Shin) and found to be 70 seconds. The smooth surface of this film was laminated so as to be in contact with the silicone rubber layer of the waterless planographic plate TAP to form a waterless planographic printing plate precursor. It took 15 seconds to bring the positive film into close contact with this printing plate precursor using a vacuum printing frame. Thereafter, when the film was exposed and developed, there was no blurring due to poor adhesion between the positive film and the cover film.

Comparative Example 1 Thyroid 620 (average particle size determined by Coulter Counter method is 12μ, 10% by weight or less of 2μ or less and 20% by weight of 20μ or more).

A film was produced in the same manner as in Example 1 using a refractive index of 1.46). The smoothness of this film was measured and found to be 30 seconds. Using this film, waterless lithographic printing plate precursors were prepared in the same manner as in Example 1, and exposed and developed with a positive film brought into close contact with the plates at different vacuum contact times. Blurred printing occurred in both the plates subjected to vacuum contact for 1 minute and the plates subjected to vacuum contact for 15 seconds.

Example 2 A coating solution having the following composition was applied to a polyethylene terephthalate film “Lumirror” (manufactured by Toshi) with a thickness of 8 μm,
It was dried at 100°C for 30 seconds.

(a) Saturated polyester resin (“Vylon 2” manufactured by Toyobo Co., Ltd.)
00'', refractive index 1.58) 100 parts by weight (b) Natural silica (manufactured by Shiraishi Kogyo, average particle size 4.5μ by Coulter Counter method, 2μ or less is 20% by weight or less and 20μ
10% by weight or less, refractive index 1.58)
6 parts by weight (C) Toluene 477 parts by weight (d) Methyl ethyl ketone 477 parts by weight The thickness of the coating layer after drying was Ig/r&, and the amount of particles added was 0.057 g/%. The smoothness of this film was measured and found to be 65 seconds.

A waterless lithographic printing plate precursor was prepared using this film in the same manner as in Example 1, and exposed and developed with a positive film in close contact with the plate. Although vacuum contact was carried out for 15 seconds, there was no blurring at all.

Comparative Example 2 The natural silica of Example 2 was mixed with titanium oxide (20% by weight of titanium oxide with an average particle diameter of 4μ by the Coulter-Counter method and 2μ or less).
A coating liquid was prepared by changing the following and one having a refractive index of 2.7 or less and having a refractive index of 2.7 to 10% by weight or less, and was coated and dried to prepare a film. The thickness of the coated layer after drying was Ig/rrf. The smoothness of this film was measured to be 90 seconds. The appearance of this film was milky white. A waterless lithographic printing plate precursor was prepared using this film in the same manner as in Example 1, and exposed and developed with a positive film attached thereto. Although vacuum adhesion was performed for 1 minute, blurring occurred.

Example 3 The following photosensitive composition was applied to a hydrophilized aluminum plate with a thickness of 0.3, and dried in hot air at 110°C for 1 minute to a thickness of 2.
A photosensitive layer of μ was provided.

(a) Partial ester of naphthoquinone-1,2-diazide-5-sulfonic acid (Sumilight Resin PR50622, manufactured by Sumitomo Durez) (degree of esterification 25 by elemental analysis)
%) 100 parts by weight (b) Tetrahydrofuran
800 parts by weight of the coating solution of Example 1 was then applied onto this photosensitive layer and dried at 100°C for 30 seconds. The thickness of the coating layer after drying is 1 g/lri', and the amount of particles added is 0°07 g/n? Met. When the smoothness of this image forming material was measured using an Oken type air permeability and smoothness tester, it was found to be 70.
It was seconds. A vacuum printing frame was used to bring the positive film into close contact with the imaging material for 15 seconds. Thereafter, when the image was exposed and developed, there was no blur due to poor adhesion between the positive film and the image forming material.

[Effects of the Invention] According to the present invention, the time required for vacuum adhesion of a positive film or a negative film can be significantly shortened, and printing plate workability can be further improved.

Claims (1)

[Claims] 1. A light-transmissive film for covering an image-forming material, characterized by containing particles having an average particle diameter of 4 to 9 μm and a refractive index of 1.40 to 1.70, as measured by the Coulter Counter method. 2. The light-transmitting film for covering an image-forming material according to claim 1, wherein the image-forming material is a waterless lithographic printing plate having a silicone rubber layer as an upper layer.