JP5621195B2 - Method for producing offset printing ink - Google Patents

Description

  The present invention relates to a method for producing ink for offset printing used for offset printing on low density paper such as non-coated paper and finely coated paper. More specifically, using carbon black used for tires and rubber, for offset printing that has a bluish color and has suppressed dry-down compared to carbon black for color that has been used in printing ink applications. The present invention relates to an ink manufacturing method.

  In black ink of offset printing ink, carbon black is generally used as a pigment. As the carbon black, different from bead carbon black (for rubber) used for tires and rubber, color carbon black generally referred to as non-rubber is used (Non-Patent Document 1).

  In general, carbon black has a complex agglomeration form in which spherical carbon particles called primary (basic) particles are fused and branched into a chain or irregular chain shape. Is forming. This aggregate is called an aggregate, and the degree of fusion of the primary particles forming this aggregate is called a structure. When carbon black is dispersed in an ink vehicle, it is impossible to disperse finer than an aggregate (Non-Patent Documents 1 and 2).

  The three major characteristics of carbon black are (primary) particle size, structure, and chemical properties of the particle surface, and the size of the aggregate is determined by the particle size and structure.

  The particle diameter is a numerical value calculated from the average of the primary particle diameters of carbon black observed by an electron microscope, but is in an inversely proportional relationship with the surface area, so in recent years, the nitrogen adsorption specific surface area defined by JISK62171-2. Or it is often expressed by iodine adsorption amount. In the case of carbon black produced by the furnace method, which occupies most of the current carbon black production method, the nitrogen adsorption specific surface area and iodine adsorption amount show approximate values. . When the structure is the same, it can be said that the carbon black has a larger aggregate as the iodine adsorption amount is smaller (primary particle diameter is larger).

  The structure indicates the degree of chaining of carbon black particles, and is represented by DBP (dibutyl phthalate) oil absorption measured by JISK6217-4. A carbon black having a larger DBP oil absorption indicates a carbon black having a larger structure, and can be said to be a carbon black having a larger aggregate.

Japanese Patent Application Laid-Open No. 2004-269572 discloses a printing ink composition produced from carbon black and resin varnish having specific physical properties. However, the physical property of carbon black is that the DBP oil absorption is defined as ^{30 to} 65 (cm 3/100 g), and when the DBP oil absorption is low, it is dry when printed on uncoated paper or finely coated paper. There is a possibility that the print density cannot be maintained due to large down.

  In other words, high gloss is required for sheet-fed ink or heat-set-off wheel ink, which requires high quality even during offset printing, and it is necessary to increase the smoothness of the ink film surface even when the ink is thin. Carbon black with a small aggregate is selected. However, when printing on low-density paper such as non-coated paper and fine-coated paper, the surface of the paper is not smooth (has irregularities), so the requirement for gloss is low. Furthermore, since carbon black sinks into the inside of the paper together with the ink vehicle and the printing density cannot be maintained, it is necessary to select carbon black having a large aggregate.

Therefore, when comparing the characteristics of carbon black recommended for printing ink use and carbon black recommended for newspaper ink use in Non-Patent Document 1, carbon black recommended for newspaper ink use is the amount of iodine adsorbed. Is small (particle diameter is large) or DBP oil absorption is large, and the respective characteristics are substantially within the following ranges.
Nitrogen adsorption specific surface area: 45-95 m ² / g
DBP oil absorption: 60~115cm ³ / 100g

  HAF (N330), ISAF (N220), and FEF (N550), which are representative varieties of rubber-like bead-like carbon black, have large DBP oil absorption. Judging from the characteristic values, printing ink for low density paper It can be said that the carbon black is relatively suitable for the application. In particular, HAF has both nitrogen adsorption specific surface area and DBP oil absorption within the range of characteristic values of carbon black recommended for newspaper ink applications.

  However, on the other hand, since the ink film thickness on the paper after printing becomes thin in offset printing, in order to obtain a uniform ink film thickness, coloring power and stable printed matter, carbon black is sufficiently dispersed and carbon black It is necessary to remove impurities inside.

  Generally, carbon black contains impurities (foreign matter) such as iron rust coming from devices such as coke grains generated in carbon black generation called a grid, exfoliation pieces of a furnace, and a heat exchanger. Although it is removed using a micron separator as a foreign matter removal, the carbon black for rubber has a larger amount of grid than the carbon black for non-rubber (carbon black for color). When there are many grid components, the deterioration of the thickness at the time of printing and the problem of abrasion resistance that scrapes the image area of the plate occur, and it cannot be used for printing ink. For this reason, the carbon black for color used in printing inks increases the purity of the raw material oil for carbon generation and controls the amount of crude oil supplied to the generator to reduce coke grain generation in order to reduce the grid component as much as possible. Or using a finer foreign substance removal device. For this reason, the manufacturing cost is higher than that of carbon black for rubber. As described above, in order to use carbon black for rubber for printing ink, it is necessary to reduce the amount of this grid component. However, since the usage is different, there is no discussion about how much it should be reduced. Japanese Patent Application Laid-Open No. 2008-169309 defines the hardness of granulated particles (indicating the hardness of carbon black beads for rubber by a measurement method according to JISK6219) (3 to 20 cN). Even if it is produced using carbon black for printing, the printing durability cannot be solved.

  For this reason, non-rubber color carbon black has been used for offset printing. Non-rubber carbon black is flaky carbon black that is slightly compressed from powdered or powdered carbon black, and is different from rubber carbon black beaded. It is also a factor that worsens the manufacturing environment.

  Examples of low-paper printing inks other than offset printing and foreign newspaper inks use beaded carbon black for rubber as a pigment. As a dispersion method, a means of dispersing a low-viscosity dispersion base obtained by premixing 95% or more of the compounding prescription including carbon black with a sand mill is mainly used. However, the dispersion in the sand mill with a low viscosity base is weak in resilience, so that the carbon black solidified in the form of beads cannot be sufficiently dispersed, and mixing of elementary particles called short path is inevitable. For this reason, in offset printing, ink deposits on the plate when it is thinned, causing poor adhesion, or even if it is sufficiently dispersed, if the carbon black itself has a lot of grid components, the image area of the plate is scraped off. This is a cause of trouble with friction resistance, and is not a practical production method in Japan.

  Japanese Patent Application Laid-Open Nos. 2002-322407 and 2002-322408 disclose methods of producing carbon black and a resin varnish that is solid at room temperature in advance by dry pulverization and adding a solvent or the like to mix them. ing. Moreover, although it is described that specific carbon blacks are used, when these carbon blacks are used and this manufacturing method is used, the structure is destroyed and uncoated paper or finely coated paper, etc. For low-grade paper applications, the printing density cannot be maintained, which is not appropriate. In addition, there is a problem of printing durability, and offset printing cannot be performed.

  However, rubber-like bead-like carbon black has characteristics suitable for printing inks on low-density paper typified by newspaper ink, and there is a long-awaited production method that makes full use of it from the environmental aspect of production. Has been.

JP 2004-269572 A JP 2002-322407 A JP 2002-322408 A

“Carbon Black Yearbook No. 58 (2008)” edited by Carbon Black Association "Carbon Black Handbook" April 15, 1995, 3rd edition, Editorial publisher Carbon Black Association

  The present invention provides an ink capable of stable offset printing on low-density paper such as non-coated paper and fine-coated paper with ink using bead carbon black for rubber, and is unavoidable with conventional dispersion means. An object of the present invention is to provide a method for producing an offset printing ink in which undispersed elementary particles are suppressed as much as possible.

  As a result of diligent studies to solve the above problems, by mixing a specific rubber carbon black with varnish and solvent, premixing at 80 to 140 ° C. and dispersing and kneading the carbon black sufficiently, The present inventors have found a method for producing a black ink that has the same printing durability as carbon black for non-rubber and has a bluish color tone and suppresses dry-down, and has led to the present invention.

That is, the present invention is a method for producing an offset printing ink containing carbon black, a resin and a solvent.
Dibutyl phthalate (DBP) oil absorption 80~140 (cm ³ / 100g), iodine adsorption 30~100 (m ² / g) and sieve residue 0.003 wt% or less of the rubber bead carbon black, a varnish and a solvent And a premixing process at 80 to 140 ° C. for 20 to 300 minutes.

  Furthermore, the present invention relates to the above method for producing an ink for offset printing, wherein the varnish contains one kind selected from rosin-modified phenolic resin, petroleum resin and alkyd resin.

  The present invention also relates to a method for producing the above offset printing ink, wherein the solvent is one kind selected from petroleum solvents and vegetable oils.

  Furthermore, this invention relates to the ink for offset printing manufactured by the manufacturing method of said ink for offset printing.

  The present invention also relates to the above-described offset printing ink, which is a permeation drying type.

  Furthermore, this invention relates to the printed matter formed by printing the said offset printing ink on a base material.

  By using the present invention, it has become possible to produce an ink for offset printing that has a bluish hue and suppresses dry-down as compared with conventional carbon black for rubber. Moreover, it becomes possible to reduce environmental loads, such as dust generated by using conventional powdery carbon black, and the industrial value of the present invention is enormous.

  The best mode for carrying out the present invention will be specifically described below.

  Carbon black, which is the first essential component according to the present invention, is a carbon black for rubber (Non-Patent Documents 2 and 3) generally used for tires and rubbers, and has the following physical properties. This is different from non-rubber carbon black (commonly referred to as color carbon black) that has been used for printing inks.

  The demand for carbon black (on a supply basis) is about 910,000 tons / year in 2007. Among them, carbon black for rubber is about 95%, 860,000 tons / year, and carbon black for non-rubber used for printing ink is about 5%, 50,000 tons / year. Large supply of black. Among the carbon blacks for rubber, the production method of the present invention makes it possible to use those having specific physical properties as inks for offset printing.

Physical properties required in the carbon black for rubber according to the present invention, DBP oil absorption amount to the first (in the present invention, be measured in accordance with ASTM D-2414.) In the range of 80~140 ^(cm 3 / 100g) It is necessary to be in More ^{preferably, 90~130 (cm 3 / 100g)} , more preferably it is necessary that 95~125 ^(cm 3 / 100g). When the ink for printing the low density of the sheet, DBP oil absorption amount is 80 (cm 3 ^/ 100g) be smaller than the paper quality deterioration due blackness shortage after dry down is large printing occurs. Further, DBP oil absorption amount ¹⁴⁰ (cm 3 / 100g) reduced larger than ink fluidity thereof significantly, not obtained good dispersibility.

Furthermore, as a further characteristic of the carbon black of the present invention, the iodine adsorption amount (measured in accordance with ASTM D-1510 in the present invention) is in the range of 30 to 100 (m ² / g). Necessary, preferably 40 to 95 (m ² / g), more preferably 45 to 90 (m ² / g). The physical property value of iodine adsorption is common in carbon black for rubber. As described above, the amount of adsorbed iodine is in an inversely proportional relationship with the primary particle size. When the numerical value is small, the particle size is increased, and further, the aggregate diameter is increased. In the case of ink for printing on low density paper, the larger the aggregate diameter, that is, the smaller the iodine adsorption amount, the more advantageous for dry-down, but the iodine adsorption amount is 30 (m ^2). / G), the aggregate diameter is too large, so that the dispersibility is deteriorated and the friction resistance is deteriorated. In addition, when the iodine adsorption amount is larger than 100 (m ² / g), the aggregate diameter is decreased, which causes a problem of dry-down.

  Further, as a further characteristic of the carbon black of the present invention, the sieve residue (in the present invention, measured in accordance with ASTM D-1514 [# 325 mesh]) must be 0.003 wt% or less. Yes, preferably 0.002 wt% or less, more preferably 0.001 wt% or less.

  The sieve residue is filtered through a 325 mesh (about 45 μm), and a mesh with a larger opening cannot capture the grid component deposits.

  Further, as described above, carbon black contains foreign matters such as iron rust coming from devices such as coke grains generated in the generation of carbon black called a grid, furnace peeling pieces, and heat exchangers. If there are many grid components, there will be a problem of wear resistance during printing and a problem of friction resistance that scrapes the image area of the plate, resulting in insufficient printed matter and damage to the printing press. Therefore, it cannot be used as a printing ink. The grid component is directly proportional to the sieve residue, and if it exceeds 0.003 wt%, a problem of friction resistance will occur.

The premixing method (pre-dispersion) in the present invention may be a commonly used machine such as a rotor / stator type pre-dispersing machine or PSI in addition to a tank with a stirring blade conventionally used in ink for offset printing. It is even better to have a heating device such as a steam or hot water jacket. The temperature during pre-dispersion needs to be 80 to 140 degrees, preferably 100 to 120 degrees. If the temperature is lower than 80 degrees, the dispersion is insufficient and the printing durability is deteriorated. If the temperature is higher than 140 ° C., the dispersion becomes excessive, the bonds between the aggregates are decomposed, and the dry-down suppressing effect is reduced. The mixing / pre-dispersing time needs to be 20 to 300 minutes, preferably 30 to 240 minutes. If the time is shorter than 20 minutes, the dispersion is insufficient and the printing durability is deteriorated. If the time is longer than 300 minutes, the dispersion becomes excessive, the bonds between aggregates are decomposed, and the effect of suppressing the dry-down is reduced. End up.
Furthermore, the addition amount of the carbon black of the present invention is preferably 10 to 30% by weight in the printing ink.

  As the resin used in the present invention, in addition to the rosin-modified phenolic resin, rosin-modified maleic acid resin, alkyd resin, petroleum resin and the like can be used alone or in combination of two or more. The weight average molecular weight of the resin is preferably 20,000 to 300,000. If the weight average molecular weight is less than 20,000, the ink has insufficient viscoelasticity, and if it exceeds 300,000, the fluidity of the ink becomes insufficient.

  The resin (rosin-modified phenolic resin, rosin-modified maleic resin, alkyd, petroleum resin, etc.) is a solvent that is at least one selected from petroleum solvents and vegetable oils, and in some cases a gelling agent such as an aluminum chelate compound. It is added and used as a varnish formed by melting at about 190 degrees. The addition amount of the resin is 20% to 50% by weight with respect to the total amount of the printing ink composition.

  The vegetable oils in the present invention are vegetable oils and compounds derived from vegetable oils. Among the triglycerides of glycerin and fatty acids, at least one fatty acid is a fatty acid having at least one carbon-carbon unsaturated bond, and triglycerides thereof. Examples include fatty acid monoesters obtained by ester reaction with saturated or unsaturated alcohols.

Typical vegetable oils are: Asa seed oil, flaxseed oil, eno oil, psyllium oil, olive oil, cacao oil, kapok oil, kaya oil, mustard oil, kyounin oil, kiri oil, kukui oil, walnut oil, poppy oil, sesame oil , Safflower oil, radish seed oil, soybean oil, daikon oil, camellia oil, corn oil, rapeseed oil, niger oil, nuka oil, palm oil, castor oil, sunflower oil, grape seed oil, gentian oil, pine seed oil Cottonseed oil, palm oil, peanut oil, dehydrated castor oil, and the like. Especially soybean oil, coconut oil, linseed oil and rapeseed oil are preferable.
In the present invention, the vegetable oil esters used include fatty acid esters derived from vegetable oils such as soybean oil, cottonseed oil, linseed oil, safflower oil, tall oil, dehydrated castor oil, canola oil, and rapeseed oil. Examples of the fatty acid ester include monoalkyl ester compounds, and the fatty acid constituting the monoester is preferably a saturated or unsaturated fatty acid having 16 to 20 carbon atoms, stearic acid, isostearic acid, hydroxystearic acid, oleic acid, linol. Examples include acids, linolenic acid, eleostearic acid and the like. The alcohol-derived alkyl group constituting the fatty acid monoester preferably has 1 to 10 carbon atoms, and examples thereof include methyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and 2-ethylhexyl. These fatty acid monoesters can be used alone or in combination of two or more. In the present invention, vegetable oils and fatty acid esters may be used alone or in combination as vegetable oil components. The amount of the solvent added is preferably 10 to 50% by weight in the ink.

  The petroleum solvent used in the present invention is a paraffinic or naphthenic solvent, and is a mixed solvent thereof. The content of the aromatic hydrocarbon in the solvent is preferably 1% by weight or less. The aniline point of the solvent is preferably 65 ° to 110 °. When a solvent having an aniline point higher than 110 degrees is used, the solubility of the resin in the ink composition is poor, so that the fluidity of the ink is insufficient, and only a glossy printed matter can be obtained due to poor leveling. In addition, in an ink using a solvent having an aniline point lower than 65 degrees, the detachment of the solvent from the ink film at the time of drying may be poor and may cause drying deterioration.

In the present invention, when carbon black is dispersed in the varnish, pigments other than carbon black such as organic bentonite, calcium carbonate, barium sulfate, clay, and silica can be added. can get.
As other auxiliaries used in the present invention, additives such as dispersants, gelling agents, drying inhibitors, antioxidants, antifriction agents (waxes) can be used as appropriate.

The compounding ratio of carbon black for rubber and varnish in the present invention is preferably set at 100 to 150 parts by weight of varnish with respect to 100 parts by weight of carbon black.
In the present invention, the substrate to be printed may be anything as long as it meets the purpose of the offset printing ink of the present invention, which is a osmotic dry type (a substrate into which a solvent penetrates), but paper, particularly uncoated paper or Substrates that are osmotically dried, such as finely coated paper or re-paper, are suitable as the substrate for printing of the present invention.

  Next, the present invention will be described based on examples. However, the scope of the present invention is not limited to the following examples. In the present invention, “part” and “%” mean “part by weight” and “% by weight”, respectively, unless otherwise specified.

[Production example of rosin-modified phenolic resin varnish]
38.5 parts of rosin-modified phenolic resin (Arakawa Chemical Industries, Ltd.) having an average molecular weight of 80,000, an acid value of 20, and a softening point of 165 degrees, 30 parts of soybean oil, AF solvent No. 5 (new) 30 parts (aniline point, 88.2 degrees, manufactured by Nippon Oil Co., Ltd.), heated to 180 degrees, stirred at the same temperature for 30 minutes, allowed to cool, and ethyl acetoacetate aluminum diisopropoxide 1 as a gelling agent 0.0 part (ALCH manufactured by Kawaken Fine Chemical Co., Ltd.) was charged and stirred at 180 degrees for 30 minutes to obtain a rosin-modified phenolic resin varnish.

[Production example of gilsonite resin varnish]
Charge 42 parts of aliphatic hydrocarbon resin (ER-125 made by AMERICANGILSONITE COMPANY) and 58 parts of soybean oil extracted from gilsonite, and heat and stir at 140 degrees for 1 hour to obtain gilsonite resin varnish. It was.

[Ink production example]
The obtained resin varnish, carbon black and solvent (AF Solvent No. 6 (manufactured by Shin Nippon Oil Co., Ltd., aniline point 93.6 degrees)) were mixed in Table 1 and pre-dispersion temperature / hour for rotor / stator type pre-dispersion. After pre-dispersing with a machine (peripheral speed: 20 m / s), kneading and mixing were performed using a three-roll and a mixer, and inks of Examples and Comparative Examples were produced.The inks had a tack value of Toyo Seiki Co., Ltd. It adjusted with the digital incometer so that it might become 3.5-4.0 on the conditions of 30 degree | times, ink 1.32cc, and 400 rpm.

Table 2 shows a property comparison table of carbon black (CB) used in the present invention.

* Sieve residue: 325 mesh CB1 to CB5 are carbon black for rubber. CB6 is a color carbon black for ink.

[Printing evaluation test]
About the ink of the said Example and the comparative example, the monochrome printing and the halftone dot (1 to 100% of 10% increments) printing and normal character printing were performed on the following printing conditions.

[Printing conditions]
Printing machine: LITHOPIA BT2-800 NEO (Mitsubishi Heavy Industries, Ltd.)
Paper: Newspaper renewal: Super lightweight paper (43 g / m ² ) (Nippon Paper Industries Co., Ltd.)
(Colorimetric value: L ^* : 83, a ^* : -0.25, b ^* : 5.5)
Dampening water: NEWSKING ALKY (Toyo Ink Manufacturing Co., Ltd.) 0.5% tap water solution Printing speed: 100,000 copies / hour Plate: CTP plate (Fuji Film Co., Ltd.)
Number of copies: 100,000 copies

[Dry-down evaluation method]
The density values immediately after printing and after 24 hours were measured using a spectrophotometer SpectroEye manufactured by Gretag Macbeth Co., and the difference was calculated by the following formula and evaluated. The larger the value, the greater the decrease in print density due to drydown.

Formula (1)

[Printed material measurement conditions]
Concentration: spectrophotometer SpectroEye manufactured by Gretag Macbeth
45/0, D50, 2 degree field of view, Status T

[Method of evaluating hue]
Color measurement was performed with the above spectrophotometer using a printed matter that had passed 24 hours after printing, and L ^* a ^* b ^* was measured. The hue was evaluated based on the measured b ^* value. b ^* represents a yellowish hue as the value is large, and a blue hue as the value is small.

[Method for evaluating printing durability]
The printed matter is sampled every 5,000 minutes, and the degree of the solid print portion and the Japanese character portion is evaluated, and the damage degree of the image portion of the CTP plate after printing 100,000 copies is based on the following evaluation criteria. Evaluation was performed.
(Evaluation criteria)
A: No damage on the CTP print line part: No deterioration of the printed material up to 100,000 parts.
○: Slight damage to the CTP printing line area: Slightly deteriorated in the printed material up to 100,000 copies.
○ △: Damaged CTP print line part: Confirmed deterioration of printed material up to 100,000 parts.
Δ: Damaged CTP print line part: Confirmed deterioration of printed matter by 70,000 copies.
X: Damage of CTP printing line part severely: Confirmed deterioration of printed matter by 50,000 parts.

[Evaluation results]
Table 3 shows the evaluation results.

As a result, when compared with Examples 1 and 2, Comparative Examples 1 and 2 have substantially the same dry-down amount and b ^* value indicating bluishness, but the printing durability required for printability is very poor. It has become. This is due to the fact that the carbon black of Comparative Examples 1 and 2 has a large amount of grid components, that is, the amount of sieve residue is large. Comparative Example 3 also has the same tendency, with a small dry-down amount and a bluish hue, but poor printing durability. Comparative Examples 4 and 5 are carbon blacks commonly used in inks, but there is no problem with printing durability, but the dry-down amount is large. Moreover, the bluish hue is equivalent. In Comparative Examples 6 and 7, the dry-down amount is small and the hue is bluish, but the printing durability is poor. In Comparative Example 6, the pre-dispersion temperature is low, and in Comparative Example 7, the pre-dispersion time is short. Comparative Example 8 has good printing durability but a large amount of dry-down. This is because Comparative Example 8 has a long pre-dispersion time.

  As described above, by using the carbon black for specific rubber of the present invention, the printability such as printing durability is maintained at the same level as the conventional powdery carbon black, and it has a bluish color and is dry-down. Thus, an ink for offset printing and a printed matter in which is suppressed can be obtained, which can contribute to improvement and stabilization of the paper surface quality.

Claims (6)

In the manufacturing method of offset printing ink containing carbon black, resin and solvent,
Dibutyl phthalate (DBP) oil absorption 80~140 (cm ³ / 100g), iodine adsorption 30~100 (m ² / g) and sieve residue 0.003 wt% or less of the rubber bead carbon black, a varnish and a solvent A method for producing ink for offset printing, comprising a step of premixing at 80 to 140 ° C. for 20 to 300 minutes. The method for producing an ink for offset printing according to claim 1, wherein the varnish contains one kind selected from rosin-modified phenolic resin, petroleum resin and alkyd resin. The method for producing an ink for offset printing according to claim 1, wherein the solvent is one kind selected from petroleum solvents and vegetable oils. The ink for offset printing manufactured by the manufacturing method of the ink for offset printing in any one of Claims 1-3. The ink for offset printing according to claim 4, which is a permeation drying type. A printed matter obtained by printing the offset printing ink according to claim 4 on a substrate.