JPH0336863B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to aqueous printing ink compositions. The basic properties required of printing inks, especially aqueous ink compositions for flexographic printing, are (1) excellent pigment dispersibility, (2) appropriate values of fluid properties such as viscosity and viscosity; 3) The ink does not scatter on the printing press, (4) It sets and dries quickly and has excellent blocking properties, (5) The printed surface is uniform and clear, (6) It does not contain organic solvents. and (7) excellent physical and chemical properties of the coating. Conventionally, the vehicle components of water-based printing inks generally include water-soluble resins such as polyvinyl alcohol, polyvinyl methyl ether, polyethylene oxide, and polyacrylates, and the water-soluble resins, surfactants, and protective colloids (polyvinyl alcohol,
Water-based resins are used in combination with emulsions obtained by emulsion polymerization of polymerizable monomers using hydroxyethyl cellulose, etc., as emulsifiers. However, the former ink composition using a water-soluble resin as a vehicle component generally has the disadvantage that the solid content is low and drying properties are insufficient, and the printed coating has poor physical and chemical properties. Furthermore, in an ink composition containing the latter aqueous resin as a vehicle component, the emulsion in the composition exhibits the effect of increasing the solid content and improving the drying properties of the water-soluble resin. However, since the addition of the emulsion impairs the film-forming properties of the printed coating, a large amount of organic solvent is generally added. In addition to the above, ink compositions containing emulsions have poor wettability with printing materials, especially metals, resulting in uneven and unclear printed surfaces, and also have poor physical and chemical properties of the printed film. There is. The present inventors used a mixture of a water-soluble resin and a specific vinyl polymer emulsion at a certain ratio as a vehicle component for water-based printing inks, and by adjusting the TI value (thixotropic index) of the ink composition, the above-mentioned results were obtained. The present invention has been completed by discovering that the above disadvantages can be overcome and the properties required of a water-based ink composition can be satisfied. That is, the present invention provides water-soluble resin 5 having a carboxyl group and an oxidatively polymerizable unsaturated bond as a solid content.
~60% by weight and 95% to 40% by weight of a vinyl polymer emulsion obtained by emulsion polymerization of a polymerizable vinyl monomer with a Q value of 0.1 or more as determined by Q and e theory using maleated polybutadiene as an emulsifier. The mixture is used as a base resin, and the viscosity at 20℃ is 100~
3000 centipoise, a TI value (thixotropic index) of 1.2 to 3.0, and an organic solvent content of less than 5% by weight. The water-soluble resin used in the present invention is a resin having a carboxyl group and an oxidatively polymerizable unsaturated bond in the resin, and is used after being neutralized with a neutralizing agent. As the resin, conventionally known resins can be used, such as fatty acid-modified alkyd resins, fatty acid-modified vinyl resins, fatty acid-modified vinyl alkyd resins, maleated polybutadiene, and the like. The water-soluble resin described above can be obtained as follows. First, the fatty acid-modified alkyd resin is made of (semi)drying oil and/or (semi)drying oil fatty acid (hereinafter referred to as "(semi)drying oil fatty acid"), polyhydric alcohol, polybasic acid and A mixture of monobasic acids is prepared according to a known synthesis method, for example, in an inert gas atmosphere at about 150 to 250°C for about 3 to 10 hours.
For dehydration condensation reaction, and for further maleation, add (anhydrous) maleic acid and heat at approximately 50 to 230℃.
The reaction can be carried out for about 1 to 5 hours, and the content of (semi-)drying oil fatty acid residues in the resin is about 10 to 70
% by weight, especially about 20-60% by weight is preferred. The (semi-)drying oil fatty acid is a component that imparts oxidative hardening properties to the alkyd resin, and higher unsaturated aliphatic monocarboxylic acids having at least one carbon-carbon double bond in one molecule are preferably used, generally 6
It may contain up to 30 carbon atoms, preferably 17-20 carbon atoms. Such fatty acids include drying oil fatty acids with an iodine value greater than 130 and
80-130 semi-drying oil fatty acids are included, specifically, for example, tung oil, dehydrated castor oil, sesame oil, sunflower oil, walnut oil, rubber seed cob, linseed oil, safflower oil, soybean oil, corn oil, cottonseed oil , grape kernel oil, cornseed oil, eno oil, silica oil, sugarcane oil, rice bran oil, fatty acids thereof, tall oil fatty acids, high diene fatty acids, and the like. Also,
Examples of polyhydric alcohols include glycerin, trimethylolethane, trimethylolpropane,
Examples of polybasic acids include pentaerythritol, ethylene glycol, propylene glycol, neopentyl glycol, etc., and aromatic-allylic alcohol copolymers such as styrene-allylic alcohol copolymers, and examples of polybasic acids include (anhydrous) phthalic acid and isophthalic acid. , terephthalic acid, trimellitic acid (anhydride), glutaric acid, adipic acid, maleic acid (anhydride), itaconic acid, tetrahydrophthalic acid (anhydride), fumaric acid, etc., and monobasic acids include:
Examples include benzoic acid, p-tert-benzoic acid, coconut oil fatty acid, and the like. Fatty acid-modified vinyl resin is a fatty acid-modified vinyl monomer obtained by reacting a (semi-)drying oil fatty acid with a glycidyl group-containing unsaturated monomer, ethylenically unsaturated carboxylic acid, and other ethylenically unsaturated monomers. For example, the copolymer described in JP-A-50-126723 can be used. The fatty acid-modified vinyl alkyd resin is produced by synthesizing the above-mentioned fatty acid-modified alkyd resin with benzoyl peroxide, di-tert-butyl peroxide, azoisobutyronitrile, etc. in a carbon dioxide atmosphere using a synthesis method known per se. Utilizing free hydroxyl groups or carboxyl groups in fatty acid-modified alkyd resins and those obtained by copolymerizing ethylenically unsaturated monomers such as (meth)acrylic esters and styrene in the presence of a polymerization initiator. It is possible to use a resin which is reacted with a vinyl polymer containing functional groups (hydroxyl group, carboxyl group, glycidyl group, etc.). Maleated polybutadiene is an addition reaction product of polybutadiene or butadiene copolymer having a number average molecular weight of about 200 to 4000 and maleic acid (anhydride). Here, polybutadiene is 1,2-
It may have a vinyl structure, a 1,4-trans structure, or a 1,4-cis structure, and other monomers having a carbon number of 2 to 18 may be used as raw materials for the butadiene copolymer. Examples include olefins, dienes (eg, isoprene, chloroprene, cyclopentadiene), acrylic esters, methacrylic esters, styrene, vinyltoluene, acrylonitrile, and the like. As mentioned above, among the above-mentioned water-soluble resins, fatty acid-modified alkyd resins and fatty acid-modified vinyl resins containing an aromatic unsaturated monomer-allyl alcohol copolymer as the alcohol component have excellent initial drying properties and pigment dispersibility. This is preferable in this respect. The acid value of the water-soluble resin can be an amount necessary for the resin to dissolve in water, and is generally about 20 or more, preferably in the range of about 30 to 200. As a neutralizing agent for neutralizing water-soluble resin,
Animonia, amines, alkali metal compounds, etc. can be used. The amount of the neutralizing agent to be blended is generally about 0.1 to 2.0 equivalents, preferably about 0.3 to 1.0 equivalents, relative to the carboxyl groups in the resin. In the present invention, the polybutadiene or (semi-)drying oil fatty acid used for the water-soluble resin has excellent pigment dispersibility and can obtain a highly concentrated pigment paste even with a small amount, and also contains oxidation-hardening unsaturated groups. This gives the printed coating excellent physical and chemical properties. The vinyl polymer emulsion used in the present invention is obtained by emulsion polymerization of a polymerizable vinyl monomer having a Q value of about 0.1 or more as determined by Q and e theory using polybutadiene maleate as an emulsifier. The emulsion described in JP-A-48-73488 is used. Note that the Q, e theory in this specification refers to the theory that expresses the addition reaction rate constant of a monomer to a radical, which was first proposed by Alfrey and Price in 1947.
The Q value is a constant representing the general reactivity of the monomers that constitute this theory, and generally, the higher the radical reactivity of the monomer, the larger the Q value. (Q,
Regarding the theory e, please refer to [Introduction to Polymer Chemistry, Osaka City University Polymer Chemistry Research Group], pages 81 to 88 (published by Kobunshi Publishing Co., Ltd. on April 30, 1968). ) The emulsion will be explained below. The butadiene polymer, which is the raw material for maleated polybutadiene, has a number average molecular weight of about 200 to about
4,000, preferably from about 500 to about 10,000 polybutadiene or 10% or more as butadiene units;
Preferably, a butadiene copolymer having the above number average molecular weight containing 40% or more is included. If the number average molecular weight of the butadiene-based polymer does not reach about 200, the maleated polybutadiene obtained will hardly function as a polymeric emulsifier and will only serve as a low-molecular emulsifier. In addition, a butadiene polymer having a number average molecular weight of more than about 40,000 is undesirable because its viscosity becomes too high, making the maleation reaction difficult. In the present invention, to maleate the above-mentioned butadiene-based polymer, the polymer is subjected to an addition reaction with maleic acid or maleic anhydride. This reaction may be carried out by placing the polymer in a reaction vessel together with maleic acid or maleic anhydride and, if necessary, a solvent, thoroughly purging with nitrogen, and heating to 150°C to 250°C with high-speed stirring. When maleic acid is used in the maleation reaction, the maleated polybutadiene thus obtained is subjected to emulsion polymerization after neutralizing the carboxylic acid groups. On the other hand, when maleic anhydride is used, it is ring-opened with water, alcohol, amine, etc. to form dicarboxylic oxides, half-esterified products, and half-amidated products, which are then subjected to emulsion polymerization in the same manner after neutralizing the carboxylic acid groups. . The degree of maleation, ring opening and neutralization described above is such that the acid value of the maleated polybutadiene after final neutralization is approximately 20.
The range is from about 350 to about 350, preferably from about 40 to about 200. If the acid value is lower than about 20, it will not be effective as an emulsifier and the desired polymer emulsion cannot be produced. Neutralizing agents used for neutralizing carboxylic acid groups include ammonia, amines, and alkali metal hydroxides, oxides, carbonates, and bicarbonates. Primary, secondary, or tertiary amines commonly used as agents, as well as polyvalent amines such as diamines, triamines, and tetramines, can be used. The amount of maleated polybutadiene used (when used during emulsion polymerization of polymerizable vinyl monomers) is such that the acid value based on the total solid content generated by emulsion polymerization is approximately 10-150. The maleated polymer is blended into the mixture. Next, examples of polymerizable vinyl monomers with a Q value of about 0.1 or more as determined by the Q, e theory include, for example, the general formula

Acrylic ester or methacrylic ester, glycidyl methacrylate, glycidyl acrylate, methoxybutyl acrylate, methacrylate represented by the formula (where R ₁ represents hydrogen or a methyl group, and R ₂ represents an alkyl group having 1 to 18 carbon atoms) Methoxybutyl acrylate, ethoxybutyl acrylate, ethoxyethyl methacrylate, ethoxybutyl acrylate, ethoxybutyl methacrylate, allyl acrylate, allyl methacrylate, styrene, α-methylstyrene, vinyltoluene, butadiene, isoprene, acrylonitrile, methacrylonitrile, etc. can be mentioned. These polymerizable vinyl monomers may be used alone or in combination of two or more. As the polymerization conditions for emulsion polymerization of the polymerizable vinyl monomer, generally known polymerization conditions can be effectively applied as they are. In the vinyl polymer emulsion used in the present invention, the maleated polybutadiene used as an emulsifier has excellent wettability to printing materials, especially metals, and can provide a uniform and clear printed film. Furthermore, since the maleated polybutadiene has excellent compatibility with the water-soluble resin described above, the resulting ink composition has good storage stability and can be printed uniformly. Furthermore, the maleated polybutadiene is oxidatively cured to give the printed film excellent properties such as blocking resistance, adhesion, impact resistance, and water resistance. In addition, since the maleated polybutadiene itself has excellent film-forming properties, it is possible to form a uniform printed film without cracking or peeling. The blending amount of the resin component in the aqueous printing ink composition of the present invention is 5 to 60% by weight of the water-soluble resin, preferably 20 to 50% by weight in terms of solid content, and 95 to 40% by weight of the vinyl polymer emulsion in terms of solid content. % by weight, preferably 80-50% by weight. The amount of water-soluble resin blended is less than 5% by weight (vinyl polymer emulsion is 95% by weight)
If the amount of water-soluble resin is greater than
% by weight (vinyl polymer emulsion
40), the solid content is low and the printed film dries slowly, making it unsuitable for high-speed printing on industrial lines, and the physical properties of the film are poor, causing it to peel off due to the impact of the printing material. There are drawbacks such as poor chemical properties and poor chemical properties, so it is necessary to fall within the above-mentioned range. The aqueous printing ink composition of the present invention can be prepared according to methods known in the field of paint or ink production, such as all or part of a water-soluble resin or its neutralized product. A pigment paste obtained by dispersing the pigment using a pigment paste, and the remainder if a portion of the water-soluble resin is used,
The vinyl polymer emulsion and the dryer can be mixed together, and if necessary, conventional additives such as antifoaming agents, viscosity modifiers, plasticizers, and fungicides can be added. Examples of pigments that can be used include coloring pigments such as titanium white, carbon black, cyanine blue, cyanine green, red iron oxide, fast-stretched red, sintered red, and chrome green, and extender pigments such as talc, mica, clay, silica, and calcium carbonate. The pigment can be dispersed by using a dispersing machine such as a ball mill, sand mill, super mill, roll, etc. to a particle size of about 40 μm or less. The amount of pigment blended varies depending on the type of pigment, but is generally about 30 to 80% by weight based on the weight of the resin component of the ink composition. As a dryer, Co, Pb, Mn, Ca, Zn, Fe,
Salts of metals such as Zr and Cu and acids such as naphthenic acid, linseed oil fatty acid, tall oil fatty acid, rosin, and diethylhexaninic acid can be used. The amount of the dryer is generally about 0.01 to 2.0% by weight of the metal content based on the (semi-)drying oil fatty acid component. of the aqueous printing ink composition prepared as above.
The TI value ranges from 1.2 to 3.0, preferably from 1.5 to 2.0. If the TI value is less than 1.2, the thixotropy becomes low and the desired wall thickness cannot be obtained, while if it is greater than 3.0, fluidity is lost and the printing of characters becomes unclear. The above-mentioned TI value represents the degree of thixotropy, and the larger the value, the greater the thixotropy. The TI value is a value determined by the following formula using a Bismetron viscometer manufactured by Precision Equipment Research Institute (measurement temperature: 20°C). TI value = Viscosity measured at 6 rpm / Viscosity measured at 60 rpm In addition, the viscosity of the water-based printing ink composition can be used within the range of several 100 to 3000 cps (centipoise), preferably 500 to 1000 cps, up to a measurement temperature of 20°C. can. If the viscosity is outside this range, printing will not be possible. The aqueous printing ink composition of the present invention is also characterized by a low concentration of organic solvent, about 5% by weight or less. The aqueous printing ink composition of the present invention can be printed using a conventional printing press, such as an offset printing press, a relief printing press, or a concave printing press. Also,
Examples of printing materials include metal, wood, slate, cardboard, and plastic, but it is particularly preferred to use metals such as tin, aluminum, steel, and zinc. The printed coating generally ranges from about 1 to 25 .mu.m, preferably from about 5 to 15 .mu.m, as a dry printed coating. The printed film dries in about 10 seconds or less at room temperature. Since the water-based printing ink composition of the present invention is the above-mentioned composition and has a TI value within a specific range, it overcomes the drawbacks of conventional water-based printing ink compositions, that is, the organic solvent content is 5%. Because of the above, it gives off an unpleasant odor to workers and cannot be used safely because it is regulated by the Industrial Safety and Health Act.
Poor wettability with printing materials, especially metal surfaces, resulting in uneven and unclear printed surfaces, and poor physical and chemical properties of printed films such as blocking resistance, adhesion, impact resistance, and water resistance. etc., and
Moreover, it satisfies the above-mentioned requirements for a water-based ink composition for flexographic printing. Examples All parts and % in the examples indicate parts by weight and % by weight. Production example of water-soluble resin (A) The following ingredients were added to the reaction vessel: RJ-101 (manufactured by Monsanto, trade name, styrene,
Allyl alcohol copolymer) 585 parts linseed oil fatty acid 708 parts 0.5 part dibutyltin oxide was added, heated to 240°C in the presence of nitrogen gas atmosphere, and a dehydration condensation reaction was performed for 10 hours to obtain a reaction product with an acid value of 3.9. . Next, the temperature was lowered to 200°C, 73 parts of maleic anhydride was added, and a maleation reaction was carried out for 3 hours to obtain a water-soluble resin (Gardna viscosity W to X, acid value 65). Next, 50 parts of xylene, butyl cellosolve 480
1 part and then 72 parts of deionized water to obtain a dissolved varnish. Next, it was neutralized with 24 parts of aqueous ammonia and 85 parts of triethylamine to obtain a fatty acid-modified vinyl resin varnish with a solid content of 65%. Production example of water-soluble resin (B) Linseed oil fatty acid 236 parts Glycidyl methacrylate 119 parts Hydroquinone 0.4 parts Tetraethylammonium bromide 0.2 parts were placed in a reaction vessel. While stirring the reaction,
It was carried out at a temperature of 140-150°C. The addition reaction between epoxy groups and carboxyl groups was monitored while measuring the amount of remaining carboxyl groups. It took about 4 hours for the reaction to complete. Next, 50 parts of n-butyl cellosolve was placed in a reaction vessel and heated to 120°C. A mixture in the proportions shown below was then added dropwise to this solution over a period of about 2 hours. The reaction was carried out under nitrogen injection. The above addition reaction product: 60 parts n-butyl methacrylate 30 parts Acrylic acid 10 parts Azobisisobutyronitrile 4 parts The reaction temperature was maintained at 120°C, and the above mixture was added dropwise while stirring the reaction solution. One hour after the completion of the dropwise addition, 1 part of azobisisobutyronitrile was added to the reaction solution, and after another 2 hours, 1 part of azobisisobutyronitrile was added to the reaction solution, and then for 3 hours.
The reaction was carried out while maintaining the temperature at 120°C. Polymerization rate 99.7
%, and a polymer with an acid value of 75 was obtained. 13.5 parts of triethylamine (neutralization equivalent: 1.0) and deionized water were added to the above polymer to obtain a fatty acid-modified vinyl resin varnish with a solid content of 65%. Production example of vinyl polymer emulsion (A) Polybutadiene (number average molecular weight 3000, 1,4-
8% cis type, and 92% 1,2-vinyl type) 200
1, 80 parts of maleic anhydride, 100 parts of methyl isobutyl ketone and 150 parts of xylene were sealed in an autoclave, and after thorough nitrogen gas purging, the autoclave was heated at 185-195° C. for 5 hours with high speed stirring to react.
After the reaction, after removing the solvent and excess maleic anhydride, 60 parts of ethyl acetate, 64 parts of methanol, and 16 parts of water were added.
After stirring at 60°C for 6 hours, 60 parts of n-butyl cellosolve was added, and methanol, water, and ethyl acetate were removed using an evaporator. Product acid value 74,
The solution concentration was 77%. Next, 332 parts of clean water, 5.7 parts of 28% aqueous ammonia, 2.8 parts of n-butyl cellosolve, and 88 parts of the above product and 0.4 parts of ammonium persulfate were placed in a reaction vessel and dissolved well. Then, 172 parts of n-butyl methacrylate was added, and under nitrogen injection. 70℃
The mixture was stirred for 3 hours to obtain an emulsion with a solid content of 40%. Production example of vinyl polymer emulsion (B) Polybutadiene (molecular weight 1900, 1,4-cis type
70%, 1,4-trans type, 27% and 1,2-vinyl type 1%), 45 parts of maleic anhydride, and 75 parts of xylene were sealed in an autoclave, thoroughly replaced with nitrogen gas, and then heated to 190% while stirring at high speed. −200℃
The mixture was heated for 5 hours to react. After thorough washing with reaction water, 60 parts of butyrocellosolve was added and water was removed using an evaporator to obtain a maleated polybutadiene solution. The maleated polybutadiene had an acid value of 116 and a concentration of 76.4%. Next, 100 parts of clean water, 10 parts of 28% aqueous ammonia, and 40 parts of the above product and 0.2 parts of ammonium persulfate were placed in a reaction vessel and dissolved. 67.2 parts of butyl methacrylate and 5 parts of acrylamide were added, and under nitrogen injection, 50 parts of ammonium persulfate was added. The mixture was stirred at 56° C. for 2 hours to obtain an emulsion with a solid content of 43% and an acid value of 20.2. Example 1 After pre-kneading, pigments were dispersed in a pebble ball mill using the following formulation. Dispersion time is 16~
The particle size after dispersion for 18 hours was less than 40 μm. Water-soluble resin (A) 40 parts Titanium oxide 360 parts Hydrous magnesium silicate 100 parts Polyalkylsiloxane 2 parts Methanol 5 parts Cellosolve 3 parts Water 90 parts Next, the following raw materials were sequentially added to the above pigment paste while stirring. Water-soluble resin (A) 54 parts Lead naphthenate 2 parts Cobalt naphthenate 0.5 parts Vinyl polymer emulsion (A) 307 parts Water 36.5 parts The resulting water-based ink composition has a solid content of 65% and a viscosity of
It showed 440cps. Examples 2 to 11 Water-based printing ink compositions of Examples 2 to 11 were obtained using the same manufacturing method as in Example 1 using the formulations shown in Table 1. Properties of the aqueous printing ink compositions of Examples 1 to 11,
The results of printability and film performance are shown in Table 2. Comparative Example 1 Water-soluble resin C (methyl methacrylate, styrene,
Ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, acrylic resin solution neutralized with 1.0 equivalent of ammonia in a 65% solution of isopropyl alcohol with an acid value of 200 and a softening point of 100°C obtained by copolymerizing acrylic acid) and Roplex B-15 (Rohm and Haas Co., Ltd., copolymer latex of ethyl acrylate, methyl methacrylate, and acrylic acid, solid content 46%) and vinyl polymer emulsion C were used with the formulation shown in Table 1. The production was carried out analogously to Example 1. The properties of this composition,
Printability and performance results are shown in Table 2. Comparative Examples 2 to 5 Water-based printing ink compositions were obtained in the same manner as in Example 1 using the formulations shown in Table 1. The properties, printability, and performance results of these compositions are shown in Table 2.

【table】

Claims (1)

[Claims] 1 Polymerizable vinyl monomer whose solid content is 5 to 60% by weight of a water-soluble resin having carboxyl groups and oxidation-polymerizable unsaturated bonds and maleated polybutadiene as an emulsifier, and whose Q value determined by Q and e theory is 0.1 or more. The base resin is a mixture of 95% to 40% by weight of a vinyl polymer emulsion obtained by emulsion polymerization of the polymer, and the viscosity at 20°C is 100 to 3000 centipoise, and the TI value (thixotropic index) is 1.2.
~3.0 and an organic solvent content of less than 5% by weight.