JPH0577710B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a binder for printing ink.
For more details, please refer to plastic as printing material,
In particular, the present invention relates to a binder for printing ink that exhibits excellent adhesion and printability to polypropylene, polyester, and nylon films. [Prior Art] In recent years, various types of plastic films have been developed as packaging materials as packaging contents have become more complex and packaging technology has become more sophisticated.As a result, it has become necessary to appropriately select a film that is compatible with the contents. It is becoming more and more used. Conventionally, rosin-modified maleic acid resins, nitrified cotton, polyamide resins, chlorinated polypropylene, polyurethane resins, resins made of vinyl chloride-vinyl acetate copolymers, polyester resins, etc. have been used as binder components in plastic film printing ink compositions. Among these, polyurethane resins have been used in increasing amounts in recent years because they exhibit excellent adhesion to various plastic films. However, when polyurethane resin is used as a printing ink binder, it has poor printing suitability due to poor resolubility, and as a result, it has the disadvantage of causing so-called "plate jam" or "plate fog" phenomenon during printing. is blocking resistance,
There is a problem that pigment dispersibility is poor. On the other hand, printing inks using acrylic resins are generally used for paper coatings and paper printing inks, and although they are known to have good printability, it is difficult to use acrylic resins for plastic films. There is a problem in that the adhesion is insufficient in some cases, making it impractical. That is, at present, there is no excellent printing ink that has excellent adhesion to various plastic films as printing materials and does not cause any problems in terms of printability. Therefore, in view of the above-mentioned technical background, there is a strong need for a versatile printing ink binder that has excellent adhesion and printability on any plastic film. Therefore, considering the loss of interest between polyurethane resin and acrylic resin, it is expected that a mixture of polyurethane resin and acrylic resin will improve both adhesion and printability. However, simply adding and mixing an acrylic resin to a polyurethane resin results in poor compatibility, resulting in a decrease in the stability of the resulting ink, which not only tends to separate the ink but also tends to reduce its adhesion to the plastic film. This is not desirable. [Problems to be Solved by the Invention] The present inventors have solved the above-mentioned problems that could not be solved by the conventional techniques, namely, for polypropylene, polyester, and nylon films as printing substrates. As a result of intensive research to develop a printing ink binder with excellent adhesion and printability,
A completely new fact that all of the above problems can be solved if a resin mixture obtained by blending polyurethane resin with a specific proportion of acrylic resin containing special functional groups in the molecule is used as a binder. I found out. The present invention was completed based on this new knowledge. [Means for Solving the Problems] The present invention provides a polyurethane resin (A) obtained by reacting a polymer polyol, a diisocyanate compound, and a chain extender, and a group consisting of a pyridium base, a sulfonic acid group, and a sulfonic acid group. The present invention relates to a binder for ink, which is formed by mixing an acrylic resin (B) containing at least one functional group selected from the above in its molecule. In other words, the present invention combines various polyurethane resins with acrylic resins having special functional groups in the molecule in a specific proportion, and uses these as binders to create printing inks that use conventional polyurethane resins as the main binder. This can solve the above-mentioned problems that could not be solved at all. [Function and Examples] The binder for printing ink of the present invention is a group consisting of a polyurethane resin (A) obtained by reacting a polymer polyol, a diisocyanate compound, and a chain extender, and a pyridium base, a sulfonic acid group, and a sulfonic acid group. It can be obtained by mixing the acrylic resin (B) containing at least one functional group selected from the above in its molecule. The polymer polyol component which is a component of the polyurethane resin (A) includes polyether polyols such as polymers such as ethylene oxide, propylene oxide, and tetrahydrofuran, or copolymers thereof; ethylene glycol, 1,2-propane; diol, 1,3-propanediol, 1,3-
Saturated or unsaturated low molecular weight glycols such as butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, hexanediol, octanediol, 1,4-butenediol, diethylene glycol, triethylene glycol, dipropylene glycol, etc. and dibasic acids such as adipic acid, phthalic anhydride, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid or Polyester polyols obtained by dehydration condensation of acid anhydrides corresponding to these; polyester polyols obtained by ring-opening polymerization of cyclic ester compounds; other polycarbonate polyols, polybutadiene glycols, bisphenol A with ethylene oxide or oxidation Examples include various known polymer polyols commonly used in the production of polyurethane, such as glycols obtained by adding propylene. Among the above polymer polyols, when a polymer polyol obtained from glycols and dibasic acids is used, up to 5 mol% of the glycol component can be replaced with the following various polyols. That is, for example, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,
It can be substituted with 2,4-butanetriol, pentaerythritol, sorbitol, etc. The molecular weights of the various polymer polyols mentioned above are determined appropriately by taking into account the solubility, drying properties, blocking resistance, etc. of the polyurethane resin obtained, and are usually
It is best to set it within the range of 500 to 3000. The molecular weight is
If it is less than 500, printability tends to be poor due to a decrease in solubility, and if it exceeds 3,000, drying properties and blocking resistance tend to decrease. Furthermore, within a range that does not deviate from the performance of the resulting polyurethane resin, a part of the above-mentioned high-molecular polyol component can be replaced with low-molecular polyols, and the amount used in the polyol component is usually 20% by weight. % or less, preferably 10% by weight or less. Examples of the low-molecular polyols include various low-molecular polyols used in the production of the polymer polyols. If the proportion of low-molecular polyols used exceeds 20% by weight, the adhesion of the resulting printing ink composition to plastic film and the solubility in diluting solvents tend to decrease. Examples of the diisocyanate compound that is a component of the polyurethane resin (A) include aromatic, aliphatic, and alicyclic diisocyanates.
For example, 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzylisocyanate,
dialkyldiphenylmethane diisocyanate,
Tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,
4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, 2,2,
4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dichlorohexylmethane-4,4'-diisocyanate, 1,3 -Bis(methyl isocyanate)
Representative examples include cyclohexane and methylcyclohexane diisocyanate. In addition, chain extenders include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine,
Isophoronediamine, dicyclohexylmethane
Examples include 4,4'-diamine. Also, diamines having a hydroxyl group in the molecule, such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxyethylethylenediamine, -Hydroxypropylethylenediamine and the like can be used similarly. Furthermore, if necessary, a dialkylamine such as di-n-butylamine can also be used as a polymerization terminator. As a method for producing the polyurethane resin of the present invention, first, a polymer polyol component and a diisocyanate compound are reacted under conditions with an excess of isocyanate groups to prepare a prepolymer having isocyanate groups at both ends of the polymer polyol. There is a two-step method in which this is reacted with a chain extender and/or polymerization terminator in an appropriate solvent, or a polymer polyol component, a diisocyanate compound, and a chain extender and/or polymerization terminator are reacted at once in an appropriate solvent. Although any one-step reaction method may be employed, the former method is preferred for the purpose of obtaining a uniform polymer solution. In these manufacturing methods, the solvents used are usually aromatic solvents such as benzene, toluene, and xylene, which are well known as solvents for printing inks; ethyl acetate,
Ester solvents such as butyl acetate; methanol,
Alcohol solvents such as ethanol, isopropanol, and n-butanol; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, and the like may be used alone or in a mixture of two or more. When producing the polyurethane resin (A) used in the present invention by a two-step process, it is preferable to mix a chain extender and/or a polymerization terminator with the prepolymer according to the following criteria. That is, the free isocyanate groups that the prepolymer has at both ends are
In terms of equivalents, the total equivalent of amino groups in the chain extender and/or polymerization terminator is preferably within the range of 0.9 to 1.30 equivalents. Amino group is 1.30
If the amount is in excess of the equivalent amount, the chain extender and/or polymerization terminator will remain unreacted, which will adversely affect printed matter in terms of odor. The molecular weight of the polyurethane resin (A) used in the present invention obtained as described above is preferably within the range of 5,000 to 10,000. If the molecular weight is less than 5,000, the drying properties, blocking resistance, film strength, and oil resistance of printing inks using it as a binder will be poor, and if it exceeds 100,000, the viscosity of the polyurethane resin solution will be poor. The gloss of printing ink tends to increase and the gloss of printing ink tends to decrease. The resin solid content concentration of the polyurethane resin solution obtained as described above is not particularly limited, and is determined as appropriate considering workability during printing, and is usually 15
~60% by weight, and the viscosity is 50~100000cP (25
℃) is practically suitable. The acrylic resin (B), which is another binder component used in the present invention, is a pyridium base,
Contains at least one functional group selected from the group consisting of a sulfonic acid group and a sulfonic acid group,
It is preferable that the functional group is contained in an amount of 5×10 ⁻⁶ to 5×10 ⁻⁴ gram equivalent per gram of solid content of the acrylic resin (B). Polyurethane resin (A) if the content of functional groups is less than 5×10 ^-6 gram equivalent
If the amount exceeds 5 x 10 ^-4 gram equivalent, the solubility in organic solvents decreases, resulting in ink separation and poor pigment dispersibility. Since it becomes stable, the effect of adding the acrylic resin (B) no longer appears. As the main component of the acrylic resin (B), it is possible to use acrylic esters and/or methacrylic esters, which generally exhibit excellent effects on printability. Hereinafter, acrylic acid and/or methacrylic acid will be referred to as (meth)acrylic acid. (Meth)acrylic acid ester monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate,
Butyl (meth)acrylate, (meth)acrylic acid 2
- (meth) such as ethylhexyl, stearyl (meth)acrylate, lauryl (meth)acrylate, etc.
Acrylic acid alkyl ester monomer or 2-hydroxyethyl (meth)acrylate, (meth)
Commonly commercially available monomers include (meth)acrylic acid hydroxyalkyl ester monomers such as 2-hydroxypropyl acrylate. In addition, all monomers of the acrylic resin (B) component
A styrene monomer may be added in a range of 0 to 50 parts to 100 parts (by weight, hereinafter the same) and copolymerized. The acrylic resin containing a pyridium base in the molecule includes the above (meth)acrylic acid ester monomer, a vinyl monomer containing a pyridium base,
For example, by copolymerizing 4-vinyl-N-propylpyridium salt, 2-vinyl-N-propylpyridium salt, etc., or by copolymerizing the above (meth)acrylic acid ester monomer with a vinyl monomer containing a pyridyl group, for example, 2-vinyl-N-propylpyridium salt, etc. -vinylpyridine, 4-
Copolymerize with vinylpyridine, etc., and then
It can be obtained by quaternizing with a grading agent. Examples of quaternizing agents include dimethyl sulfate,
Examples include dialkyl sulfates such as diethyl sulfate; halogenated hydrocarbons such as methyl chloride, benzyl chloride, methyl iodide, and ethyl bromide. The acrylic resin containing a sulfonic acid group or a sulfonic acid group in the molecule is composed of the above-mentioned (meth)acrylic ester monomer and a monomer containing a sulfonic acid group or a sulfonic acid group, such as 2-acryloylamino-2-methyl-1. - Obtained by copolymerizing propanesulfonic acid or its salt, p-styrenesulfonic acid or its salt, etc. The acrylic resin (B) is prepared by combining the (meth)acrylic acid ester monomer and at least one member selected from the group consisting of the pyridium base, sulfonic acid group, and sulfonic acid group in a suitable solvent with benzoyl peroxide, azo 50-150℃ in the presence of a polymerization initiator such as bisisobutyronitrile
It is prepared by carrying out a reaction at The solvent used in the preparation of the acrylic resin (B) may be the same as that used in the production of the polyurethane resin. The molecular weight of the acrylic resin (B) used in the present invention obtained as described above is preferably in the range of 3,000 to 200,000. If the molecular weight is less than 3000, if this is used as a binder,
Printing ink film strength, drying properties, blocking resistance, etc. are poor, and when it exceeds 200,000, the effect of improving resolubility decreases. In addition, the glass transition point (hereinafter referred to as Tg) is -
If the temperature is lower than 20°C, blocking resistance tends to decrease. The viscosity and concentration are not particularly limited, and are determined appropriately taking into consideration workability during printing, and usually have a concentration of 20 to 70% by weight and a viscosity of 50 to 50%.
A temperature of 100000cP (25°C) is practically suitable. Polyurethane resin (A) obtained as described above
and acrylic resin (B) at a weight ratio (A)/(B) of 1/1~
It is preferable to mix them in a ratio of 20/1, and use them as is or further diluted to make a binder for printing ink. If the weight ratio is less than 1/1, the adhesion will decrease, and if it exceeds 20/1, no effect on printability will be observed, which is not preferable. This binder is appropriately mixed with a colorant, a solvent, a surfactant for improving ink fluidity and a surface film, wax, and other additives as needed, and is then used in a conventional ink mill such as a ball mill, attritor, or sand mill. Printing ink is obtained by kneading using manufacturing equipment. The printing ink prepared in this way has excellent adhesion to various plastic films, has excellent re-dissolution properties during printing, and does not cause problems such as so-called "plate clogging" and "plate fogging." A clear print finish can be obtained. Furthermore, it exhibits excellent properties such as blocking resistance and pigment dispersibility. Production example 1 100 parts of poly(butylene adipate) glycol with a molecular weight of 2000 and 22.2 parts of isophorone diisocyanate were placed in a polymerization container and heated at 100°C under a nitrogen stream.
The free isocyanate value was 3.36%.
A homogeneous solution of urethane prepolymer was prepared by adding 81.5 parts of methyl ethyl ketone to this prepolymer. Then, 8.87 parts of isophoronediamine,
adding 203.7 parts of the urethane prepolymer solution in the presence of a mixture consisting of 122.4 parts of methyl ethyl ketone and 101.9 parts of isopropyl alcohol;
Then, the mixture was reacted at 50°C for 3 hours. The polyurethane resin solution thus obtained has a resin solid content concentration of 30
The weight percent and viscosity were 3800 cP (25°C). Production Example 2 A polyurethane resin was obtained in the same manner as in Production Example 1, using polyoxytetramethylene glycol having a molecular weight of 2000 instead of poly(butylene adipate) glycol. The resin solution thus obtained has a resin solid concentration of 30% by weight and a viscosity of 1000cP.
(25℃). Production Example 3 Consists of 75 parts of methyl ethyl ketone, 16 parts of isopropyl alcohol, 99 parts of methyl acrylate, 10 parts of a 10% by weight aqueous solution of 2-acryloylamino-2-methyl-1-propanesulfonic acid, and 1 part of aazobisisobutyronitrile. The mixed solution was placed in a polymerization container, heated while stirring, and reacted at 70° C. for 5 hours.
The acrylic resin solution thus obtained has a resin solid content concentration of 50% by weight, a viscosity of 1100cP (25℃), and a Tg.
The temperature was 8°C. Production example 4 75 parts of methyl ethyl ketone, 25 parts of isopropyl alcohol, 60 parts of methyl acrylate, 38 parts of styrene
1 part of 4-vinylpyridine and 1 part of azobisisobutyronitrile was placed in a polymerization vessel, heated with stirring, and reacted at 70°C for 5 hours.
Thereafter, 2.4 parts of benzyl chloride was added and the mixture was refluxed for 2 hours. The acrylic resin solution thus obtained has a resin solid content concentration of 50% by weight and a viscosity of 50% by weight.
The temperature was 700cP (25℃) and Tg was 39℃. Production Example 5 0.7 part of triethanolamine was added to the solution synthesized in Production Example 3, and the mixture was refluxed for 2 hours. The acrylic resin solution thus obtained has a resin solid content concentration of
50% by weight, viscosity was 1100cP (25°C), and Tg was 8°C. Production Example 6 A mixed solution consisting of 75 parts of methyl ethyl ketone, 25 parts of isopropyl alcohol, 100 parts of methyl methacrylate, and 1 part of azobisisobutyronitrile was placed in a polymerization vessel, heated with stirring, and reacted at 70°C for 5 hours. The acrylic resin solution thus obtained has a resin solid content concentration of 50% by weight and a viscosity of 50% by weight.
The temperature was 4300cP (25℃) and the Tg was 100℃. Production Example 7 A mixed solution consisting of 75 parts of methyl ethyl ketone, 25 parts of isopropyl alcohol, 100 parts of methyl acrylate, and 1 part of azobisisobutyronitrile was placed in a polymerization vessel, heated with stirring, and reacted at 70°C for 5 hours. The acrylic resin solution thus obtained has a resin solid content concentration of 50% by weight and a viscosity of 1300cP.
(25°C), Tg was 8°C. Each mixture having the composition shown in Table 1 was milled in a ball mill to prepare eight white printing inks. To 100 parts of each of the resulting printing inks, 35 parts of methyl ethyl ketone and 15 parts of isopropyl alcohol were further added to adjust the viscosity. The prepared white ink was tested and evaluated based on the following items. (Stability of Ink) The sedimentation property of the white pigment in the white ink whose viscosity was adjusted was observed and evaluated. (Adhesion) The above adjusted ink was printed on corona discharge stretched polypropylene film (hereinafter referred to as OPP), polyethylene terephthalate film (hereinafter referred to as PET), and nylon film (hereinafter referred to as NY) using a rotogravure printing machine. . Paste cellophane adhesive tape on the printed surface,
One end of this cellophane adhesive tape was rapidly peeled off in a direction perpendicular to the printed surface, and the condition of the printed surface was observed and evaluated. (Blocking resistance) Apply the above adjustment ink on a rotogravure printing machine.
Print each in NY. The printed surfaces were placed on top of each other and held at a temperature of 40° C., a humidity of 80%, and a pressure of 1 Kg/cm ² for 3 hours, and then peeled off to observe and evaluate the degree of ink peeling. (Re-soluble) Apply the above adjustment ink on a rotogravure printing machine.
After printing on NY for 1 minute at a printing speed of 100 m/min, the presence or absence of clogging of the roll plate was observed and evaluated. (Pigment dispersibility) Apply the above adjusted ink on a rotogravure printing machine.
Each was printed on NY and the gloss of the printed surface was evaluated by observation.

[Table] (2): Methyl ethyl ketone was used as the dilution solvent.

[Table] From the above results, it can be seen that when the binder of the present invention is used, excellent adhesion and printability are exhibited for various plastic films. [Effects of the Invention] The printing ink binder of the present invention has excellent adhesion and printability to various plastic films, so it can be applied to various uses as a highly versatile printing ink binder. .

Claims (1)

[Scope of Claims] 1. A polyurethane resin (A) obtained by reacting a polymeric polyol, a diisocyanate compound, and a chain extender, and at least one member selected from the group consisting of a pyridium base, a sulfonic acid group, and a sulfonic acid group. A binder for printing ink made by mixing an acrylic resin (B) containing a functional group in the molecule. 2. The printing ink according to claim 1, wherein the polyurethane resin (A) and the acrylic resin (B) have a weight ratio ((A)/(B)) of 1/1 to 20/1. binder. 3 The acrylic resin (B) is the acrylic resin
The above functional group is added to 1 g of solid content of (B) in an amount of 5×10 ^-6 to 5×
10 ^-4 gram equivalent binder for printing ink according to claim 1. 4 The glass transition point of the acrylic resin (B) is -
The binder for printing ink according to claim 1, which has a temperature of 20°C or higher.