JPH03138196A - Preparation of improved plate material for planographic printing - Google Patents

Abstract

PURPOSE:To enhance the printing durability and image reproducibility by preliminarily pretreating the surface of a film or sheet with plasma. CONSTITUTION:In preparing a plate material for planographic printing by sulfonating a film or sheet composed of a polymer of an ethylenic monomer, the surface of the film or sheet is preliminarily pretreated with plasma. In this case, non-equilibrium plasma said to be low temp. plasma or low pressure plasma in general can be used. A printing plate is prepared using the plate material for planographic printing by treating the film or sheet with plasma and subsequently sulfonating the same to make it possible to enhance not only the image reproducibility of printed matter when planographic printing is performed but also printing durability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improved method for producing a lithographic plate material made of a sulfonated film or sheet of an ethylene monomer polymer.

[Conventional technology]

The present inventors previously provided a novel lithographic plate material having a sulfonic acid group on the surface of a film or sheet of a polymer compound in JP-A No. 63-249895. This method forms a suitable amount of hydrophilic sulfonic acid groups that are sensitive to light and heat by sulfonating a film or sheet made of a polymer of ethylene monomer using a strongly oxidizing sulfonating agent such as sulfuric anhydride. This is a lithographic plate material that is characterized by the ability to These plates are made directly from digital signals using general-purpose thermal printers such as laser printers and thermal printers, without the need for negative film or thermal transfer sheets, and without going through processes such as fixing and development. This is a new plate material that can be used for printing.

[Problem to be solved by the invention]

However, when lithographic printing is performed using these printing plates, it has been difficult to produce a plate material that fully satisfies both image reproducibility and printing durability. That is, in general, plate materials with excellent image reproducibility of printed matter tend to have low printing durability, while printing materials with excellent printing durability tend to have low image reproducibility. The aim is to improve these problems.

[Means to solve the problem]

That is, the present invention provides a method for producing a lithographic plate material by sulfonating a film or sheet made of a polymer of ethylene monomer, which is characterized in that the surface of the film or sheet is pretreated with plasma. This relates to a method for producing a lithographic plate material, which is formed into a printing plate by forming an image using a predetermined method, and when printing is performed, the plate material has excellent both image reproducibility and printing durability of the printed matter. It provides:

In the present invention, non-equilibrium plasma, generally referred to as low temperature plasma or low pressure plasma, can be used. Plasma generated by a microwave method is preferable for the pretreatment effect of the present invention, but plasma generated by other methods such as a direct current plasma method or a high frequency method can also be used. Although an inert gas such as Ar or He can be used as the gas to be turned into plasma, it is preferable to use a chemically active gas such as O, N, or NH8. The conditions for plasma processing, such as the type of gas to be turned into plasma, the partial pressure of the gas in the processing equipment, and when generating plasma using a microwave method, the microwave output and processing time, etc., each depend on the film or sheet being processed. Appropriate processing conditions can be selected depending on the type, surface characteristics, etc. In general, the surface of a film or sheet treated with plasma undergoes various changes in properties due to wettability, degree of roughness, introduction of chemically active groups, etc., and the contact angle of water droplets on the surface changes depending on the treatment conditions. It can be used as a guideline. That is, it is necessary that the change in the contact angle due to the plasma treatment is at least 20 degrees, and if the change is less than 20 degrees, the treatment effect will be small.

The contact angle used in the present invention means the contact angle of the water drop method, and approximately 20 μg
The angle between the surface and the water droplet after 30 seconds have passed since the droplet was dropped.

The polymer of ethylene monomer used in the present invention is, for example, a homopolymer of olefin such as ethylene, propylene, butene-1,4-methylpentene-1, hexene-1, octene-1, or/and the above monomer. It is a copolymer of two different molecules and has a molecular weight of at least 10,000 or more. In addition, one or more monomers selected from vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinyl bromide may be polymerized, or other monomers such as ethylene, propylene, Examples include those obtained by copolymerizing with at least one of butene-1, hexene-1, and the like.

In the present invention, fillers such as clay, calcium carbonate, aluminum oxide, dispersants, heat stabilizers, coupling agents, etc., which are generally known as molding resin compositions, are added to the polymer of the ethylene monomer as necessary. can include those that are Further, the film or sheet may be manufactured by a known method such as a T-die method, an inflation method, or a calendar method.

In the present invention, there are no particular limitations on the method of sulfonation, and the film or sheet may be immersed in an oxidizing sulfonating agent such as fuming sulfuric acid or an anhydrous sulfuric acid gas atmosphere. A solution diluted with an organic solvent having relatively little activity against sulfuric anhydride such as carbon, chloroform, and ethylene dichloride may be used.

The preferred degree of sulfonation is between 1X10' and 10-1 m/m ffl/c- of sulfonation. The amount of sulfonation is 1 x 10-6 m/c [I
If it is less than Y, the hydrophilic effect of the sulfonic acid group is small, so it is insufficient as a non-image area of the printing plate, and scumming is likely to occur. The amount of sulfonation is 1 x 10-1 millifil
/ cJ or more, the degree of oxidative deterioration as a side reaction increases, so the amount is not appropriate, and is preferably 5 x 10 -3 milliequivalents/cJ or less.

The amount of sulfonation can be determined as follows. That is, a film with a sulfonated surface (surface area Mc-) is immersed in a 1N aqueous calcium chloride solution to reach an equilibrium state, and the amount of hydrogen chloride generated in the aqueous solution is immersed in a 0.1N aqueous sodium hydroxide solution ( The neutralization value (X cc) with the indicator phenolphthalein is determined by titration using the titer f) and calculated using the following formula.

Amount of sulfonation = (0, lx f x A material having a ratio of absorbance of a band attributed to a sulfonic acid group to at least 0.6 is used as the lithographic plate material of the present invention. At this time, it is possible to create the aforementioned negative or positive film and omit troublesome steps such as exposure and development. That is, since a lipophilic image area can be formed by scanning the hydrophilic surface layer using a modulated laser beam or a thermal head, it can be used as a printing plate as it is.

〔Effect of the invention〕

Using the lithographic plate material produced by performing plasma treatment and sulfonation in this manner, a printing plate is prepared,
When lithographic printing is performed, not only the image reproducibility of the printed matter is improved, but also the printing durability is excellent, so that the practical value can be significantly improved.

〔Example〕

The present invention will be described in detail below with reference to Examples, but the present invention is not limited thereto.

Example 1 The surface of a polypropylene film with a thickness of about 150 μm was treated with a microwave plasma treatment device (Toshiba: TMZ-9602).
C), the oxygen partial pressure was set to 0.2 Torr, the microwave output was set to 1.2 kW, and the processing time was set to 15 seconds.

The contact angle of the resulting film was 69 degrees and that of the untreated film was 106 degrees. These films were set in a dry glass container, cooled from the outside so that the internal temperature was below 0℃, and the S03 gas/nitrogen gas (volume ratio 1/2) was adjusted to 1 liter per minute. The sulfonation reaction was carried out for 2 minutes while introducing the mixture into the reaction vessel. After the reaction was completed, these films were taken out and thoroughly washed with water.
Dry. The contact angles of the films thus obtained were 23 and 27 degrees, respectively, and the amount of sulfonation was 2.5 x 10-
5 and 2.8X10 meq/cJ, the infrared absorption spectra absorbance ratios were 0.8 and 0.7.

Paste these films on a rotating plate-making roll and roll for 2 m.
/see while rotating the semiconductor laser (Sharp:
An image was formed by condensing light (LT 027MD/MF, output 10 mW) with an optical lens and scanning the surface of the film. Next, when these were attached to a lithographic printing machine as printing plates and printed, the former reproduced clear images without blurring and had a printing durability of 3,000 copies without any problems. - On the other hand, the latter was excellent in image reproducibility, but had a problem with printing durability because slight dotted background stains became noticeable after 3,000 copies were printed.

Example 2 A high-density polyethylene film having a thickness of approximately 150 μm was surface-treated in the same manner as in Example 1 using a microwave plasma treatment apparatus. The processing conditions were as follows: air was used as the plasma gas at 0.2 torr, microwave output was set at 1.2 kW, and processing time was set at 60 seconds. The contact angle of the obtained film was 51
The temperature of the untreated film was 104 degrees.

These films were set in a reaction container and Example 1
The sulfonation reaction was carried out for 15 minutes under the same conditions as above. After the reaction was completed, these films were taken out, thoroughly washed with water, and then dried. The contact angles on the film surface were 16 and 17 degrees, respectively, and the amount of sulfonation was 3.2XIO-4 and 3.
．． 3 x to -4 meq/cJ, and the absorbance ratio of the infrared absorption spectrum was 1.0 and 0.9, respectively.

After forming an image on the film thus obtained by printing using the thermal head of a word processor (Sharp = "Shoin", model WD-300F), a lithographic printing machine was used as in Example 1. I installed it and printed. The former gave printed matter with excellent image reproducibility and had no problem in durability even after printing 3,000 copies. On the other hand, the latter had printing durability of 3,000 copies without any problem, but the reproducibility of characters was slightly inferior and some blurring occurred in solid areas.

Example 3 Copolymer of ethylene and ethyl acrylate containing 45% by weight of magnesium hydroxide (ethyl acrylate content at the start of polymerization: 6.5 mol%, number average molecular mouth: approximately 30,000, crystallinity: 65%) ) was subjected to surface treatment in the same manner as in Example 1. The processing conditions were a hydrogen gas partial pressure of 0.2 torr as the plasma gas, and a microwave output of 1.2 kW.

The processing time was set to 200 seconds. The contact angle of the obtained film was 53 degrees, while the contact angle of the film without the treatment was 88 degrees. Next, these films were immersed in fuming sulfuric acid containing 35% S03 to perform a sulfonation reaction for 60 minutes. After the reaction was completed, the film was taken out, washed with water, treated with 1N strength soda water, thoroughly washed with water, and then dried. The contact angle of each film is 1
At 8 and 21 degrees, the amount of sulfonation was 5.2X10 and 4.8XlO-66 mm/ffi/cJ, and the absorbance ratio of the infrared absorption spectrum was 0.8 and 0.7.

This film was pasted on a rotating roll, and a helium-containing neon laser (NEC: GLG5400, output 10mW)
An image was formed by scanning the surface of each film with a focused beam, and then lithographic printing was performed in the same manner as in Example 1. As a result, the former had no problem in printing the s and ooo parts in terms of stiffness. Image reproducibility was also excellent. The latter had no problems in printing durability after printing 3,000 copies, but the image reproducibility was somewhat poor and blurring was observed in some places.

patent distributor Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] 1. A method for producing a lithographic printing plate material by sulfonating a film or sheet made of a polymer of ethylene monomer, characterized in that the surface of the film or sheet is pretreated with plasma. Manufacturing method for printing plates.