JPH02194075A - Production of varnish for lithographic ink - Google Patents

Abstract

PURPOSE:To prepare a varnish useful for a lithographic ink both requiring and not requiring damping water by thermally polymerizing a specific polybutadiene in a resin soln. obtd. by thermally dissolving a resin such as a rosin-modified phenol resin in a mineral oil. CONSTITUTION:A polybutadiene with a number-average MW of 100-10000 or pref. a modified polybutadiene selected from the group consisting of maleinized, epoxidized, and acrylated polybutadienes is thermally polymerized in a resin soln. obtd. by thermally dissolving at least one resin selected from the group consisting of a rosin-modified phenol resin, rosin ester resin, rosin-modified maleic acid resin, alkyd resin and petroleum resin in a mineral oil.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for producing a lithographic printing ink varnish,
In particular, we provide a method for producing a lithographic printing ink varnish that exhibits particularly excellent properties as a varnish not only for lithographic printing inks that use normal dampening water, but also for so-called waterless lithographic printing inks that do not use dampening water. That is.

<Prior art> Lithographic printing takes advantage of the repulsive nature of oil-based ink and water, and applies oil-based ink and dampening water to a printing plate consisting of a grease-sensitive image area and a non-oil-sensitive non-image area. The oil-based ink was selectively applied only to the oil-sensitive image area, and then the oil-based ink was transferred to the printing material to obtain printed matter.

However, in such lithographic printing methods, it is extremely difficult to adjust the supply amounts of oil-based ink and dampening water, and requires skill. If the adjustment is not done properly, stains may occur due to the emulsification phenomenon. In addition, problems such as poor halftone dot reproduction, decreased gloss, and piling of paper dust due to deterioration of the water resistance of the paper occur.

In order to improve the above-mentioned problems, a printing method using a waterless planographic printing plate that allows planographic printing without using dampening water has been proposed. In this type of printing plate, the non-image areas are formed of an ink-repellent material such as a silicone compound.

As described above, at present, two types of planographic printing are used: normal planographic printing that uses dampening water, and waterless planographic printing that does not use dampening water.

Now, the printing ink varnish used in ordinary planographic printing is made by dissolving resins such as rosin-modified phenol resin, rosin ester resin, rosin-modified maleic acid resin, alkyd resin, petroleum resin, etc. in vegetable oil or mineral oil in an appropriate ratio. Generally, varnishes were used with the addition of metal soap or the like, if necessary. However, due to the problem of regulating dampening water, techniques have been proposed to improve the underwater suitability of printing inks, such as adding glycols such as hexylene glycol to the ink. .

On the other hand, when regular lithographic ink is used to print for a long time in waterless lithographic printing, which is another printing method, the temperature of the plate surface rises, and the ink adheres to non-image areas, causing background smudges. This required inks specifically designed for waterless lithographic printing.

Therefore, high molecular weight resins are used as the varnish component of waterless lithographic printing inks.

11 Methods of improving the collection force and increasing the ink tack (for example, Japanese Patent Publication No. 49-32962), or adding a silicone compound to the ink or using a silicone-modified resin to prevent ink from adhering to non-image areas. (for example, Japanese Patent Publication No. 50-11287,
10124, JP-A No. 51-22405, etc.) have been proposed.

In addition, an ink whose varnish component is a modified resin obtained by heating and polymerizing a phenol resin and a resin obtained by acid-modifying a copolymer of dicyclopentadiene and a drying oil (Japanese Patent Laid-Open No. 59-1175
No. 68) has also been proposed.

<Problems to be solved by the invention> However, printing inks used in conventional lithographic printing methods that use dampening water do not have sufficient underwater suitability and require skill to adjust the dampening water. For those to which glycol or the like was added, it was difficult to adjust the amount added. Furthermore, printing inks are required to simultaneously satisfy the contradictory properties of gloss and drying properties (set).
It has been difficult to satisfy both properties at the same time.

Furthermore, these printing inks do not have printing suitability for waterless lithographic printing and are used separately.

On the other hand, inks specially designed for waterless lithographic printing, which have increased cohesive strength through the use of high molecular weight resins, do not have sufficient fluidity, and as a result, the flow of the ink from between the rollers, from the blanket to the printing surface Less metastatic to the body,
This reduced leveling, gloss, etc.

On the other hand, when silicone compounds or silicone-modified resins are used, they also reduce the surface energy of the ink film printed on the printing material, resulting in poor trapping properties in multicolor overprinting, and overprinting. The suitability for coating with various coating agents including print varnish was also deteriorated.

In addition, in the case of a modified resin obtained from an acid-modified copolymer of dicyclopetadiene and drying oil and a phenol resin, it is difficult to resist unless the cohesive force is increased using a metal chelate or metal soap. The scumming resistance is not sufficient, and if the cohesive force is increased, the above-mentioned problems are unavoidable.

Therefore, the present invention provides waterless lithographic printing that can solve the drawbacks of conventional waterless lithographic inks, such as scumming and poor trapping, without increasing the cohesive force of the ink or adding silicone compounds. The present invention aims to provide a method for producing a varnish that is particularly suitable for ink. Also,
The present invention provides an ink varnish that can be applied to lithographic printing methods that use dampening water, and also provides a varnish that improves the problems of conventional printing inks, particularly its suitability for water.

The applicant of the present invention has published Japanese Patent Application No. 62-181327 on waterless lithographic printing containing a polybutadiene-modified resin obtained by subjecting a rosin-modified phenolic resin to a heating polymerization reaction of polybutadiene or modified polybutadiene. The present invention relates to the above-mentioned application and is characterized by a method for producing a varnish for lithographic printing ink.

Means for Solving the Problem> That is, the present invention provides a method for dissolving at least one resin selected from rosin-modified phenol resin, rosin ester resin, rosin-modified maleic acid resin, alkyd resin, and petroleum resin in mineral oil by heating. In the resin solution, the number average molecule is 1
The object of the present invention is to provide a method for producing a lithographic printing ink varnish (claim 1), which comprises heating and polymerizing polybutadiene or modified polybutadiene in the range of 0.00 to 10,000.

The present invention also provides a method for producing a lithographic printing ink varnish (Claim 2), wherein the modified polybutadiene is a modified polybutadiene selected from maleated polybutadiene, epoxidized polybutadiene, or acrylated polybutadiene (claim 2); The object of the present invention is to provide a method for producing a lithographic printing ink varnish (claim 3), in which 5 to 541 parts of the polybutadiene or modified polybutadiene is polymerized per 100 parts by weight.

The present invention will be explained in detail below.

First, the polybutadiene used in the production method of the present invention has a number average molecular weight of 100 to 10,000 and a viscosity of 3.
Liquid polybutadiene with a void size of 2 to 60,000 at 0°C can be used. For example, liquid polybutadiene rich in vinyl bonds (1,2-bonds) obtained using an alkali metal compound as a catalyst is effective. However, liquid polybutadiene rich in cis and trans 1,4-bonds or mixtures thereof can also be used.

In addition, when the molecular weight of polybutadiene is 100 or less in number average molecular weight, there is a problem that a sufficient polymer cannot be obtained and the soiling temperature does not rise, and the product also has the disadvantage of having a strong odor. .

On the other hand, when the number average molecular weight is 10.000 or more, the viscosity of the polymerized product becomes too high, and when it is formed into an ink, its transferability tends to be poor, which is not desirable.

Modified polybutadiene can also be used in the same way, and examples of modified polybutadiene include maleated polybutadiene obtained by adding α/β unsaturated dicarboxylic acid such as maleic acid or its anhydride to polybutadiene, or its esterified product. can be given. The degree of modification of maleic anhydride is preferably such that about 0.3 to 3.5 mol of maleic anhydride is added to 1 mol of polybutadiene.

In addition, acrylated polybutadiene to which α/β unsaturated monocarboxylic acid such as acrylic acid is added is also mentioned, and the degree of modification thereof is about 1% per mole of polybutadiene.
．． It is preferable to add 0 to 2.0 moles.

Furthermore, epoxidized polybutadiene obtained by acting an organic peracid on polybutadiene can also be used, and a degree of modification of 20 to 9.5 moles per mole of polybutadiene is suitable.

Other modified polybutadienes having a polybutadiene skeleton and polymerizable unsaturated bonds can also be used.

Furthermore, in the varnish production according to the present invention, (A rosin-modified phenol resin, rosin ester resin, rosin-modified maleic acid resin, alkyd resin, and petroleum resin used as the fat solution are usually used as varnish components for lithographic printing inks. However, all of them are subject to
A weight average molecular weight of 1100°OOO or less is preferable from the viewpoint of gloss.

Next, a method for manufacturing a varnish according to the present invention will be explained.

First, at least one resin selected from the group consisting of rosin-modified phenol resin, rosin ester resin, rosin-modified maleic acid resin, alkyd resin, and petroleum resin is dissolved in mineral oil used as an ink solvent under heating. Create a resin solution consisting of: At this time, vegetable oil or various ester compounds described later may be mixed in, if necessary.

The heating temperature for dissolution is in the range of 60 to 280° C., and by heating for 5 to 60 minutes, the resin solution can be easily subjected to AM. After that, the above-mentioned polybutadiene or modified polybutadiene is added to the resin solution, and if necessary, a polymerization initiator is added, and the polybutadiene and/or modified polybutadiene is heated and polymerized to obtain the desired polymer. It is.

In heating polymerization of polybutadiene and/or modified polybutadiene, the desired polymer can be obtained by carrying out a heating reaction at a temperature of 60 to 280°C for 10 to 120 minutes. In addition, when using a polymerization initiator, it is necessary to carry out the reaction at a temperature of 60 to 180°C under a nitrogen atmosphere, and when carrying out the reaction without using a polymerization initiator, it is necessary to carry out the reaction at a temperature of 220 to 280°C. , the reaction can be carried out without being limited by the nitrogen atmosphere.

It is also possible to prepare polybutadiene and the like at the same time as preparing the resin solution described above, and after obtaining a sufficient solution state, add a polymerization initiator to polymerize the polybutadiene.

The amount of polybutadiene in the polymer is 10% of the coexisting resin.
It is preferable that the amount is 5 parts by weight or more and less than 50 parts by weight relative to 0 parts by weight. If it is less than 5 parts by weight, the desired effect cannot be obtained, and if it is more than 50 parts by weight, the transferability and gloss will be poor. do not have.

In addition, for the polymerization of polybutadiene, it is essential to perform a heating reaction in a resin solution as described above, and in ink using a varnish made by simply mixing polybutadiene and other resins, the desired It is not effective. In addition, the varnish of the present invention can obtain sufficient suitability for waterless lithographic printing without special gelling to increase coagulation force using metal chelate, metal soap, etc.; It is also possible to use these materials to form a gel within a range that does not impair properties.

As the polymerization initiator, those used as radical polymerization initiators can be used, and are not particularly limited.

In addition, esters that can be added during the polymerization reaction include alkyl esters of fatty acids such as lactic acid, valeric acid, caproic acid, peptylic acid, caprylic acid, capric acid, and oleic acid, oxalic acid, malonic acid, succinic acid, Examples include dialkyl esters of aliphatic dibasic acids such as azelaic acid, sebacic acid, maleic acid, and fumaric acid, and trialkyl esters of phosphoric acid.

When producing ink using the polymer thus obtained, the desired effect cannot be obtained if the amount used in the form of the polymer in the ink is less than 2% by weight, and if the amount used is 40% by weight or more. In this case, the fluidity of the ink will be poor or the tack will be high, which is unfavorable in terms of printability.

Further, even if the polymer according to the present invention is used in combination with other resin varnishes, no effect will be lost, and it is also possible to use the polymers in combination with other resin varnishes.

When producing ink, the polymer of the present invention is diluted with a solvent and used as a varnish, and other components mixed therewith are known components conventionally used for lithographic printing inks. can.

For example, drying oils and semi-drying oils that are one of these ingredients include linseed oil, tung oil, soybean oil, safflower oil, and castor oil. As such, it may be used after being rolled up during the varnish manufacturing process. Mineral oil as a solvent has a boiling point of 200
Petroleum-based solvents at ~350°C can be used, especially when used as a varnish for waterless lithography, aromatic components should be 5% by volume.
Using a solvent that does not contain the above is effective in improving heat resistance against increases in plate surface temperature.

Furthermore, as the coloring agent for the ink, those commonly used in conventional ink compositions, such as inorganic or organic pigments, can be used.

Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto.

In addition, Carry out polymerization.

<Example> 40 parts by weight of a rosin ester resin (Pentaline, manufactured by Vercules) is mixed with 15 parts by weight of a petroleum solvent (No. 6 Solvent, manufactured by Nippon Oil Co., Ltd.), and the mixture is heated and dissolved at 230° C. for 30 minutes. Then, polybutadiene (B-3000
, manufactured by Nippon Petrochemical Co., Ltd., number average molecular weight 3.000) 8
parts by weight and 0.5 parts by weight of ditertiary butyl peroxide were added, and the mixture was reacted at 160°C for about 1 hour in a nitrogen atmosphere.
Obtain the desired polymer. After that, add 3 liters of No. 6 solvent.
Add 0 parts by weight to make varnish 1.

1"LL" - In the same manner as in Example 1 above, polymers were obtained in the same manner according to Table 1, and Solvent No. 6 was added in the same manner to obtain varnishes 1 to 8.

In addition, in Example 8, in addition to the materials shown in Table 1, 2 parts by weight of butyl oleate was added to the resin solution. Similarly, comparative varnish 1 (when using a gelling agent), comparative varnish 2
and 3, respectively.

Table 2 Indigo and yellow inks A to H (Ink Production Examples 1 to 8) and inkjet (
Comparative Ink Production Example 1) is produced by a conventional method.

Indigo ink Yellow ink 20 parts by weight Pigment 11 parts by weight Varnish No. 6 Solvent 18.6 Dryer Of these,
Ink is made using a mixed varnish in which 5 parts by weight of Varnish 1 is used and the rest is Comparative Varnish 2.

In addition, for ink K (comparative ink production example 2), a mixed varnish (50150) of comparative varnishes 1 and 2 was used,
Then, 2.0 parts by weight of silicone oil (KF-96, manufactured by Shin-Etsu Silicone Co., Ltd.) is externally added to form an ink.

Regarding Comparative Ink Production Example 3), the mixed varnish used in the ink was used as the varnish, and polybutadiene B-3000 was added externally, and the ink was formed in the same manner.

Mark "U left" - Using the blue ink A-L and yellow ink A-L obtained in Ink Production Examples 1 to 9 and Comparative Ink Production Examples 1 to 3, a sheet heater was installed on the 0 plate cylinder for the printing test. A waterless lithographic plate (manufactured by Toshisha Co., Ltd.) was attached to a specially installed printing machine that made it easy to raise the temperature of the plate surface, and the temperature of the plate surface was raised without supplying dampening water. Print on coated paper.

Then, a certain solid density (indigo 1.
In 55), the plate surface temperature when scumming occurs in the non-image area of the printed material is evaluated as the scumming temperature.

On the other hand, gloss is measured using a gloss meter and the results are displayed.

Further, after a blue ink print is left for one day and night, overprinting is performed using yellow ink, and the degree of dry trapping and ink transferability are evaluated from the print.

The results are shown in Table-3.

Table 3 As is clear from the above results, the ink composition using the varnish according to the present invention has higher gloss, transferability, Conventional ink (Ink K
It can be seen that while it has the same scumming suitability as (equivalent to), it is also superior in terms of transferability and trapping.

Further, the varnish according to the present invention was added at 5% in the ink (2.5% in the resin).
4%) The effect of using the varnish specified in the present invention can also be seen in the ink J used, which is superior to the conventional inks ① and K.

Moreover, in the case of Ink L in which polybutadiene was not polymerized but simply mixed into a resin solution, it was insufficient in each evaluation item.

Ordinary lithographic plate using dampening water using ink A and ink H1 obtained in 1.8 from printing ink production example and ink K and L obtained in comparative ink production example 2.3. The printing plate used for printing is Konica Corporation's 28th edition (SM
P) Using ordinary acidic dampening water as dampening water, printability is evaluated in terms of suitability in water, gloss, transferability, and dry trapping property.

For further comparison, with the same formulation as ink production example 1,
Ink M was produced in the same manner except that Comparative Varnish 3 obtained in Comparative Example 3 was used, and Printing Test 2 was conducted in the same manner. The evaluation results are shown in Table-4.

Table 4 As is clear from the above evaluation results, the ink using the varnish according to the present invention has excellent printability even in the conventional lithographic printing method using conventional dampening water. I understand.

On the other hand, it can be seen that conventional waterless lithographic inks (added with silicone) have insufficient underwater suitability and transferability.

Effect> As described above, the waterless lithographic printing ink composition using the varnish according to the present invention has excellent gloss, transferability, and trapping suitability while maintaining the background smudge temperature at a high value. I understand that.

Furthermore, an ink composition using the varnish according to the present invention,
It can be applied to conventional lithographic printing methods that use dampening water, and is equivalent to or has better underwater suitability than conventional lithographic inks, making it extremely useful for ink left bank management at printing companies and prevention of usage errors. It is valid.

Claims (1)

[Claims] 1) Rosin-modified phenolic resin, rosin ester resin,
In a resin solution in which at least one resin selected from rosin-modified maleic acid resin, alkyd resin, and petroleum resin is heated and dissolved in mineral oil, the number average molecular weight is 100 to 10.0.
1. A method for producing a lithographic printing ink varnish, which comprises heating and polymerizing polybutadiene or modified polybutadiene in the range of 0.00. 2) The method for producing a lithographic printing ink varnish according to claim 1, wherein the modified polybutadiene is a modified polybutadiene selected from maleated polybutadiene, epoxidized polybutadiene, or acrylated polybutadiene. 3) The method for producing a lithographic printing ink varnish according to claim 1, wherein 5 to 50 parts by weight of the polybutadiene or modified polybutadiene is polymerized with respect to 100 parts by weight of the resin.