JPH09239939A - Easy-to-punch able coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve recessed shape punching property with low energy semiconductor laser by forming a film formed of at least a nitrocellulose, a urethane resin, a carbon black, and an isocyanate hardening agent on a support body made of a thermoplastic resin. SOLUTION: On a support body 2 made of a thermoplastic resin such as a polyethylene terephthalate film, a film 1 formed of a nitrocellulose, a urethane resin, a carbon black, and an isocyanate hardening agent is formed. Thus, a coating film with which recessed shape punching is performed corresponding to irradiation time of laser beam from a semiconductor laser source is produced. Accordingly, a printing plate sheet which has excellent intaglio workability with low energy semiconductor laser, can make a desired plate material in a short time, and has excellent rub resistance for a doctor blade at the time of printing can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating film which can be perforated in a concave shape with a semiconductor laser.

[0002]

2. Description of the Related Art As an example of a sheet having a concave perforation process, there are a printing plate-making sheet used for gravure printing and a laser recording sheet. Among them, a method of obtaining an intaglio plate by widely etching a surface of a metal plate is widely known as a printing plate-making sheet used for gravure printing or the like. Since the plate-making sheet for printing on this metal surface is made for each printing,
There is no problem when printing a large amount of printed matter, but if the number of printed sheets is several tens to several thousands, the printing cost per sheet is high. Further, since there is a large plate making process such as etching, the plate cannot be directly made in the office or by an individual.

In order to solve such drawbacks, a plastic sheet, which is cheaper than a metal plate, is used as a plate for printing, and the surface of the plastic sheet is irradiated with a laser beam from a laser source. A method of obtaining an intaglio has been developed. By using this method, it is possible to obtain an inexpensive plate-making sheet for printing which can be used by individuals or offices with high quality and suitable for medium quantity sheets. A plate-making sheet for printing using this plastic sheet is, for example, a conventionally known product such as extruding or calendering that is made by adding about 20% by weight of carbon black to a thermoplastic resin such as polyethylene resin, polypropylene resin or methacrylic resin. What was seated by the processing method of was used. However, a plate-making sheet for printing made of polyethylene resin or the like requires high energy in order to perform intaglio processing with a laser, and a low-energy semiconductor laser has inferior intaglio processability and takes a long time for plate-making processing. there were. On the other hand, a plate-making sheet for printing in which a resin layer containing nitrocellulose is laminated on a support has been proposed so that intaglio processing can be performed with low energy. It is low and has a drawback that it is easily scratched by a doctor blade during printing, which adversely affects the quality of the printed matter.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems, to excel in the process of making a concave hole with a low energy semiconductor laser, to have scratch resistance and good surface smoothness, An object of the present invention is to provide an easily perforable coating film that can produce a desired product in time.

[0005]

The present invention relates to a coating film in which a surface of a plastic sheet made of a thermoplastic resin is irradiated with a laser beam from a semiconductor laser source, and a concave perforation process is performed corresponding to the irradiation time. The coating film is an easily pierceable coating film in which a film composed of nitrocellulose, urethane resin, carbon black and an isocyanate curing agent is formed on a support of a thermoplastic resin, and more preferably in the film. Of the nitrocellulose is in the range of 30 to 200 parts by weight with respect to 100 parts by weight of the urethane resin, the urethane resin is a polymer whose main component is an ester polyol, and the weight average molecular weight is 10,000 to 20.
0000.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As a support for a thermoplastic resin,
There are polyethylene terephthalate (hereinafter referred to as PET) film, vinyl chloride film, polycarbonate film, polypropylene film and the like, but the PET film is preferable in consideration of surface smoothness and strength. The film formed on the support can be intaglio-processed in a short time even with a low-energy semiconductor laser, and is provided so that scratches due to a doctor blade do not easily occur during printing. The film is composed of at least nitrocellulose, polyurethane resin, carbon black and an isocyanate curing agent. Carbon black is added for absorbing laser light and imparting hydrophilicity to the intaglio portion.
It is preferable to add 5 to 20 parts by weight to 0 part by weight. 5
If it is less than 10 parts by weight, the effect of addition is poor, and if it exceeds 20 parts by weight, the dispersion stability in the resin is poor.

In the polyol which is the main component of the urethane resin, the acid components are adipic acid, sebacic acid, terephthalic acid,
Isophthalic acid, 2,6-naphthalenedicarboxylic acid, etc.
Ester type, ethylene oxide, propylene oxide, tetramethylethylene oxide in which the alcohol component is ethylene glycol, butanediol, hexanediol, pentanediol, diethylene glycol, triethylene glycol, or the like, or a combination of caprolactone and the acid component and caprolactone. There are ether type, epoxy type, etc., but the ester type is preferable from the viewpoint of scratch resistance and durability of the film. The weight average molecular weight of the urethane resin is 10,000 to 2000.
00 is preferred. Weight average molecular weight of 1000
If it is less than 0, even if it is crosslinked with an isocyanate-based curing agent, the expected scratch resistance cannot be retained, and if the weight average molecular weight exceeds 200,000, the viscosity becomes too high and it is handled in the coating process. Becomes difficult.

Addition of an isocyanate curing agent to the urethane resin for the purpose of improving the adhesion of the thermoplastic resin to the support, improving the strength and scratch resistance of the film, and improving the solvent resistance of the ink during printing. You can The type of isocyanate, for example, toluene diisocyanate, diphenylmethane diisocyanate, dimethyldiphenylene diisocyanate, xylene diisocyanate, aromatic isocyanate represented by tetramethyl xylene diisocyanate, hexamethylene diisocyanate, aliphatic isocyanate represented by trimethylhexamethylene diisocyanate, Isophorone diisocyanate,
There are alicyclic isocyanates represented by methylenebis-4-cyclohexyl isocyanate and the like, but aromatic isocyanates are preferable from the viewpoint of dryness and scratch resistance. The addition amount is preferably 1 to 10 parts by weight based on 100 parts by weight of the total of nitrocellulose and urethane resin. If it is less than 1 part by weight, the effect of addition is poor and the adhesion to the support cannot be obtained. Further, if it exceeds 10 parts by weight, it works in the direction of inhibiting the intaglio processing. The part by weight of nitrocellulose in the coating is preferably in the range of 30 to 200 parts by weight with respect to 100 parts by weight of the urethane resin. If the amount exceeds 200 parts by weight, the amount of nitrocellulose becomes excessive and the adhesion to the support is impaired, or the flexibility is insufficient and cracking easily occurs. On the other hand, if it is less than 30 parts by weight, the urethane resin becomes excessive and the intaglio processability becomes poor.

The nitrification degree of nitrocellulose is 10.7%.
It is preferably in the range of -12.2%. Nitrification degree is 1
If it exceeds 2.2%, there is a risk of ignition during handling. On the other hand, if it is less than 10.7%, the effect of promoting the intaglio processability becomes small. Solution viscosity of nitrocellulose is 1/3
If the viscosity is in the range of 2 seconds to 1/4 seconds and exceeds 1/4 seconds, the intaglio processability is not improved as expected because of high molecular weight, and the viscosity is high, so that handling is difficult. On the other hand, if the viscosity is less than 1/32 seconds, the viscosity is too low, which makes the handling difficult during the coating process. The coating is composed of 10 to 40 parts by weight of carbon black and 100 parts by weight of urethane resin, and 2 to 20 parts by weight of isocyanate curing agent to 100 parts by weight of urethane resin, with nitrocellulose and urethane resin having the above mixing ratio. The solvent solution is applied and dried by a conventionally known coating method such as a roll method, a gravure method, a knife edge method or the like to form a film having a thickness of 1 to 30 μm, preferably about 20 to 25 μm.

[0010]

EXAMPLES Examples of the present invention will be specifically described below. << Example 1 >> The coating composition used in Example 1 is prepared by the following formulation.・ Urethane resin 100 parts by weight (Bernock KL-492: Arakawa Chemical Co., Ltd., ester type, weight average molecular weight 30000) ・ Nitrocellulose 100 parts by weight (RSNC1 / 16: Asahi Kasei, nitrification degree 11.8%, solution viscosity 1 / 16 seconds) ・ Carbon black (# 3950: Mitsubishi Chemical) 20 parts by weight ・ Isocyanate curing agent 10 parts by weight (Colone L: Nippon Polyurethane Aromatic Isocyanate) ・ Methyl isobutyl ketone 200 parts by weight ・ Toluene 200 Parts by weight Apply the coating composition adjusted by the above composition by the roll method,
Dry and deposit a film with a thickness of 25 μm on PET of 0.188 mm
Formed on film. This is the plate for printing,
An intaglio process was performed with a semiconductor laser having an output of 1.53 W, and the depth of the recess was measured. Further, using a Taber abrasion tester (manufactured by Toyo Seiki Co., Ltd.), the rate of change in surface gloss was measured after a wear test was conducted 1000 times with a wear wheel CS-10F under a load of 500 g. Table 1 shows the results.

Example 2 A sample was prepared in the same manner as in Example 1 except that the content of nitrocellulose was 200 parts by weight based on 100 parts by weight of the urethane resin.
The same items as above were tested. Table 1 shows the results. <Example 3> Example 1 except that the blending amount of nitrocellulose was 30 parts by weight with respect to 100 parts by weight of the urethane resin.
A sample was prepared by the same method as described above, and the same items as in Example 1 were tested. Table 1 shows the results. Example 4 A sample was prepared in the same manner as in Example 1 except that urethane resin (Bernock KL-560: Arakawa Chemical Co., Ltd., ester type, weight average molecular weight 150,000) was used. Tested on similar items. Table 1 shows the results. Example 5 A sample was prepared by the same formulation and method as in Example 1 except that a urethane resin (Bernock KL-422: ether type manufactured by Arakawa Chemical Co., Ltd., weight average molecular weight 30,000) was used. The same items as 1 were tested. Table 1 shows the results.

Comparative Example 1 A sample was prepared in the same manner as in Example 1 except that the blending amount of nitrocellulose was 25 parts by weight with respect to 100 parts by weight of the urethane resin. Tested. Table 1 shows the results. Comparative Example 2 A sample was prepared in the same manner as in Example 1 except that the blending amount of nitrocellulose was 230 parts by weight with respect to 100 parts by weight of the urethane resin, and the same items as in Example 1 were tested. Table 1 shows the results. << Comparative Example 3 >> Urethane resin (Mytec HE6720: Mitsubishi Chemical
A sample was prepared by the same composition and method as in Example 1 except that the ester type, weight average molecular weight of 8000) was used, and the same items as in Example 1 were tested. Table 1 shows the results. Comparative Example 4 A sample was prepared in the same manner as in Example 1 except that a urethane resin (Bernock KL-840: Arakawa Chemical Co., Ltd., ester type, weight average molecular weight 210000) was used. Tested on similar items. Table 1 shows the results.

[0013]

[Table 1]

[0014]

EFFECT OF THE INVENTION The plate-making sheet for printing of the present invention has a low film-forming rate because at least a surface layer of a plastic sheet made of a thermoplastic resin is coated with a coating layer made of nitrocellulose, urethane resin, carbon black and an isocyanate curing agent. Excellent intaglio processability with energy semiconductor laser, desired plate material can be created in a short time, good scratch resistance to doctor blade during printing, and inexpensive plate-making sheet for printing that does not impair printing quality can do.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a coating film that can be easily perforated according to the present invention.

[Explanation of symbols]

 1. Film 2. Support

Claims (4)

[Claims] 1. A coating film for irradiating a laser beam from a semiconductor laser source, and performing a concave perforation process according to an irradiation time, wherein the coating film comprises:
An easily pierceable coating film, comprising a thermoplastic resin support and a film comprising at least nitrocellulose, urethane resin, carbon black and an isocyanate curing agent formed on the support. 2. The easily perforable coating film according to claim 1, wherein the weight ratio of nitrocellulose in the film is in the range of 30 to 200 weight parts relative to 100 weight parts of the urethane resin. 3. The urethane resin is a polymer containing an ester polyol as a main component.
Alternatively, the easily perforated coating film according to item 2. 4. The weight average molecular weight of the urethane resin is 10.
It is 000-200000, The easily perforatable coating film of Claim 1, 2 or 3 characterized by the above-mentioned.