JPH0322428B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a printing ink composition having excellent durability and suitable for printing on plastic film. Printing ink compositions using polyurethane solutions as vehicles have excellent adhesion to various plastic films such as polyester, nylon, and polypropylene, and are therefore used industrially. However, the printing ink compositions that have been used so far have a tendency to develop stickiness in the printed area if the printed film is treated in hot water or left under normal lighting for a long period of time. In addition, there were problems such as the printed portion peeling off due to strong friction, staining the surface of other objects, and adhering to dust, which deteriorated the appearance and reduced the commercial value. These problems are caused by deterioration, hydrolysis, etc. of the polyurethane resin used in the vehicle of printing ink compositions, and improving the hydrolysis resistance and oxidative deterioration resistance of the vehicle can solve the problem. It is necessary for the solution. When a polyurethane resin with a polyester-based polymer diol as a soft segment is used as a vehicle, there is no problem with oxidation resistance, but there is a problem with hydrolyzability. When a polyurethane resin is used as a vehicle, there is almost no problem in terms of hydrolysis resistance, but the oxidative deterioration resistance decreases. When these two types of polymer diols are used in combination, the drawbacks of each can be reduced, but the resulting printing ink composition has both drawbacks, resulting in insufficient durability. Adding an oxidative deterioration inhibitor is one method for preventing oxidative deterioration of the vehicle, but it is effective from the viewpoint of deterioration prevention. Considering that this method may be used in food packaging, problems remain in terms of safety, and this is not a preferred method of solving the problem. The present invention can address the above problems.
The present invention provides a durable printing ink composition for plastics. That is, the present invention provides a printing ink composition having as a main vehicle an organic solvent-soluble polyurethane resin obtained by reacting a high molecular weight diol, an organic diisocyanate, and a chain extender, wherein the high molecular weight diol component of the polyurethane resin is 700% A printing ink composition characterized in that it is a high molecular weight diol containing a polycarbonate diol having a number average molecular weight of ~3000. The high molecular weight diol component of the polyurethane resin used in the present invention may be entirely polycarbonate diol, but it is preferable to use other high molecular weight diols in combination, since this improves adhesion.
From the viewpoint of durability, the content of other high molecular weight diols is preferably 50% by weight or less, but if a high degree of durability is not required, 50% by weight or more of other high molecular weight diol components may be used in combination. good. Shishi 80%
Exceeding this is not preferable because the durability improvement effect decreases. Polycarbonate diols used in the invention include, for example, diols such as propane-1,3-diol, butane-1,4-diol and/or hexane-1,6-diol, diethylene glycol, triethylene glycol or tetraethylene glycol. Mention may be made, by way of example, of polycarbonate diols which are prepared by reacting diaryl carbonates such as, for example, diphenyl carbonate or with phosgene. If the number average molecular weight of the polycarbonate diol exceeds 3,000, the resulting polyurethane resin will be soft and sticky and will cause blocking when used as a printing ink composition, which is not preferable. On the other hand, when the number average molecular weight is less than 700, the resulting polyurethane resin is somewhat hard and not sticky, but when used in a printing ink composition, the adhesion decreases, and the viscosity of the ink composition also increases over time. Problems such as decreased printability occur. Therefore, the number average molecular weight of polycarbonate diol is
Preferably in the range 700-3000. The high molecular weight diols used together with the polycarbonate diol in the present invention include polyether polyols such as polymers or copolymers of ethylene oxide, propylene oxide, tetrahydrofuran, etc. ethylene glycol, propylene glycol, 1,3-butanediol, , 4-butanediol, neopentyl glycol, pentanediol, hexanediol, octanediol,
1,4-butynediol, 2-ethyl-1,3-
Polyester polyols and cyclic ester compounds obtained by dehydration condensation reaction from saturated and unsaturated low molecular weight glycols such as hexanediol, bisphenol A, diethylene glycol, triethylene glycol, and dipropylene glycol and dibasic acids. In addition to polyester polyols, polybutadiene glycols, etc. obtained by ring-opening polymerization, bisphenol A and ethylene oxide,
Glycols with propylene oxide added, etc.
Further examples include known polyols commonly used in the production of polyurethane. Among these high molecular weight diols, combination use with polycaprolactone diol is particularly preferred since the adhesion to the plastic film is improved. When the ratio of polycarbonate diol and polycaprolactone diol is in the range of 80/20 to 20/80 on a weight basis, it is superior to printing ink compositions using conventional polyurethane resins in terms of durability and adhesion. It is preferable. Examples of organic diisocyanate compounds include aromatic, aliphatic, and alicyclic polyisocyanates, such as 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and 4,4'-diphenyldimethylmethane diisocyanate. , di- and tetraalkyldiphenylmethane diisocyanate, 4,4'-dibenzylisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, toluene diisocyanate, butane-1,4-diisocyanate, 2,2 , 4-trimethylhexamethylene diisocyanate, hexane-1,6-diisocyanate, lysine diisocyanate, cyclohexane-1,4-diisocyanate, xylene diisocyanate, isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4'-
Diisocyanate (H ₁₂ MDI) is a typical example. When yellowing of the vehicle due to light is a problem, alicyclic diisocyanates such as isophorone diisocyanate and dicyclohexylmethane-4,4'-diisocyanate are preferably used as the organic diisocyanate compound. These diisocyanate compounds may be used alone or in combination of two or more diisocyanate compounds. As a chain extender, ethylene glycol, 1,
aliphatic glycols such as 4-butanediol;
Glycols such as alicyclic glycols such as 1,4-cyclohexane glycol, xylene glycol, aromatic glycols such as 1,4-dihydroxyethyleneoxybenzene, aliphatic diamines such as ethylene diamine and propylene diamine,
Examples include diamines such as alicyclic diamines such as isophorone diamine, alkanolamines such as monoethanolamine and diethanolamine, hydrazines, and hydrazides. These chain extenders can be used alone or in combination. The physical properties of the polyurethane resin obtained vary depending on the type of chain extender, but particularly preferred extenders include 4,4'-diaminodicyclohexylmethane (H ₁₂ DAM) and isophorone diamine (IPDA).
Examples include alicyclic diamines such as. The polyurethane resin used in the present invention has a molar ratio of the hydroxyl group of the high molecular weight diol to the isocyanate group of the organic diisocyanate of 1:2 to 1:5.
It is preferable that it is in the range of . When the amount of isocyanate groups is less than the molar ratio of 1:2, the chain length of the hard segment becomes short, and unless a low molecular weight high molecular weight diol is used, tackiness occurs and blocking becomes a problem. On the other hand, if the molar ratio greatly exceeds 1:5, the chain length of the hard segments becomes long, the viscosity of the polyurethane solution changes and thickens over time, the fluidity decreases, and the resulting polyurethane resin is also hard. Therefore, it is not satisfactory as a vehicle for printing ink compositions. The proportion of hard segments in the resulting polyurethane resin varies depending on the molecular weight of the high molecular weight diol, and even if the molar ratio of hydroxyl groups to isocyanate groups is within the above range, it can range from extremely flexible to hard. However, the printing ink composition of the present invention has a stress of 20 Kg/cm ² to 110 Kg/cm 2 at 100% elongation.
Polyurethane resins in the cm ² range are particularly suitable. If the stress is less than 20Kg/ ^cm2 , there will be problems with adhesion resistance and solvent resistance, and if it exceeds 110Kg/ ^cm2 , the adhesion and solvent resistance will be affected.
Since problems arise in flexibility and dilutability, it is preferable to use a polyurethane resin in the range of 20 to 10 kg/cm ² as a vehicle unless it is particularly necessary. Solvents used in the present invention include alcohols such as ethanol and isopropanol; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; ethers such as dioxane and tetrahydrofuran; aromatic hydrocarbons such as toluene; , halogenated hydrocarbons such as percrene, esters such as ethyl acetate, butyl acetate, etc., and isopropanol, acetone, methyl ethyl ketone, ethyl acetate, toluene, etc. are preferable from the viewpoint of solubility and economy. There is no need to particularly limit the resin concentration and viscosity of the polyurethane resin solution of the present invention, but workability,
5 to 60% by weight, preferably 10 to 60% by weight from economical and physical properties
In the range of 50% by weight and the viscosity at 20℃ is 1000~
A range of 500,000 cps is preferred. In the present invention, the method for producing the polyurethane resin solution is not particularly limited, and any known method may be used. For example, a method in which a diisocyanate component and a diol component are reacted at a molar ratio with an excess of isocyanate groups to create a prepolymer with full isocyanate groups at both ends, and then extended with a chain extender; A two-step method such as a method of reacting with a diisocyanate component, a one-step method of reacting three components of a diol component, a diisocyanate component, and a chain extender in one step, etc. can be carried out. In the above method, polymerization is carried out in the presence or absence of a solvent. If polymerization is carried out in the absence of a solvent, a solvent is added afterwards or a solid resin is produced once and then dissolved in a solvent to form a resin solution. A method of manufacturing is used. In the above polyurethane solution, a coloring agent such as a pigment,
Solvent, surfactant for improving ink fluidity and surface film modification as necessary, and other additives are blended as appropriate and kneaded using normal ink manufacturing equipment such as ball mill, attritor, and sand mill. Printing ink can be manufactured by doing this. The printing ink composition of the present invention comprises polyethylene,
In addition to exhibiting excellent adhesion to films such as polypropylene, polyester, and nylon, it also exhibits better hydrolysis resistance and oxidative deterioration resistance than conventional printing ink compositions using polyurethane resin as a vehicle, and has excellent durability. are doing. Furthermore, although this is an unexpected effect and the reason is not clear, the printing ink composition of the present invention has good dispersion stability of the pigment, and even if left standing for a long period of time, the pigment remains at the bottom of the container. No deposits are formed, nor is the viscosity of the printing ink composition economically altered and thickened. For this reason, it has become possible to safely produce a printing ink composition using only a polyurethane resin as a vehicle, which conventionally had concerns about dispersion stability. In producing the printing ink composition, if necessary, polymers such as nitrocellulose, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyamide, and acrylic ester polymers may be mixed. Next, the present invention will be specifically explained with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Parts in Examples and Comparative Examples represent parts by weight unless otherwise specified. In addition, in the examples, adhesiveness among printability was evaluated by Sellotape adhesiveness. The ink compositions of Examples and Comparative Examples were printed on polyester film using a gravure proofing machine.
After leaving it for a day, paste sellotape on the printed part,
When this was rapidly peeled off, those that did not peel off at all were judged as good, and those that partially peeled off were judged as bad. Blocking resistance was determined by folding each printed material so that the printed side was inside, tightly tightening it in a vise, leaving it in an air bath kept at 40℃ overnight, then spreading it out again, and visually judging the resistance at that time. Those with no resistance were judged as good, those with very slight resistance were judged as very good, and those with obvious resistance or those in which peeling was difficult were judged as poor. Of durability, hydrolysis resistance is determined by immersing a printed plastic film in hot water at 100℃ and checking whether the printed part is sticky after 72 hours. It was evaluated as having poor hydrolysis resistance. Heat deterioration resistance is determined by placing a printed plastic film in an air bath at 120°C for 96 hours and checking for stickiness in the printed area, and if it is sticky, it is evaluated as having poor heat deterioration resistance. did. If no stickiness was observed even after one week or more had passed, it was judged as good. Those exhibiting intermediate durability were rated as good. Example 1 300 parts of 1,6-hexanediol polycarbonate (PC) with an average molecular weight of 2000 and 66.7 parts of isophorone diisocyanate (IPDI) were placed in a four-necked flask equipped with a stirrer, thermometer, Dimroth, and _N2 gas inlet tube. were mixed and reacted at 95°C for 10 hours to obtain a urethane prepolymer with a free NCO% of 3.44%. Next, methyl ethyl ketone (MEK)
After adding 244.5 parts to make a homogeneous solution, add the above to a solution in which 23.3 parts of isophoronediamine (IPDA) and 2.36 parts of di-n-butylamine as a reaction terminator were dissolved in a mixed solvent of 226.3 parts of MEK and 117.7 parts of isopropanol. MEK solution of urethane prepolymer
611.2 parts were added dropwise at room temperature. After dropping, increase the temperature to 50℃
The mixture was allowed to react for 3 hours. This polyurethane resin solution had a viscosity of 12,500 cps/20°C/40%. 100%
The stress during elongation was 50 Kg/cm ² . Next, titanium oxide (Ishihara Sangyo Co., Ltd., Taipei R
-820), 37.5 parts of the polyurethane solution (polymer concentration 40%), and 23.0 parts of methyl ethyl ketone (first grade reagent) were kneaded in a ball mill for 24 hours, and then 29 parts of ethyl acetate was added to prepare the printing ink composition. Obtained. This ink composition was used to print on nylon film and polyester film using a gravure printing machine. The printing results were as shown in Table 1. This printing ink composition showed no change in viscosity even after long-term storage and had good dispersibility. Example 2 150 parts of 1,6-hexanediol polycarbonate with an average molecular weight of 2000, 150 parts of polycaprolactone (PCL) with an average molecular weight of 2000, and 66.7 parts of isophorone diisocyanate were mixed and reacted at 95°C for 10 hours until the free NCO% was 3.44. % of urethane prepolymer was obtained. Next, 244.5 parts of methyl ethyl ketone was added to make a homogeneous solution, and then 23.3 parts of isophoronediamine and 2.36 parts of di-n-butylamine were added.
To a solution dissolved in a mixed solvent of 226.3 parts of MEK and 117.7 parts of isopropanol, 611.2 parts of the homogeneous solution of the urethane prepolymer was added dropwise at room temperature. After the dropwise addition, the temperature was raised to 50°C for 3 hours. The resulting polyurethane resin solution had a viscosity of 136P/20°C/40%. The stress at 100% elongation was 45 Kg/cm ² . A printing ink composition was prepared in the same manner as in Example 1, and the printability and durability were examined. Table 1 shows the results. There was almost no increase in the viscosity of the printing ink composition over time. Example 3 200 parts of 1,6-hexanediol polycarbonate with a number average molecular weight of 2000, 50 parts of polycaprolactone with an average molecular weight of 2000, and 50 parts of polytetramethyl glycol (PTG) with an average molecular weight of 2000 were mixed with 66.7 parts of isophorone diisocyanate. The reaction was carried out at 95°C for 10 hours to obtain a urethane prepolymer with a free NCO% of 3.44%. Then methyl ethyl ketone
After adding 252.4 parts of isophorone diamine and making a homogeneous solution, 23.3 parts of isophoronediamine and di-n-butylamine were added.
611 parts of the MEK solution of the urethane prepolymer was added dropwise to a solution of 2.36 parts dissolved in a mixed solvent of 232.7 parts MEK and 121.3 parts isopropanol at room temperature and stirred.
After dropping, the mixture was reacted at 50°C for 3 hours. This polyurethane resin solution had a viscosity of 150P/20°C/40wt%. The stress at 100% elongation was 47 Kg/cm ² . A printing ink composition was prepared using the same formulation as in Example 1, and its printability and durability were examined. Results first
Shown in the table. The viscosity of the printing ink composition remained constant during storage, and the dispersion stability was good. Examples 4 to 10 Various polyurethane solutions were prepared in the same manner as the method for preparing the polyurethane resin solution described in Example 1, and printing ink compositions were prepared therefrom to examine printability and durability. Table 1 summarizes the results.

【table】

[Table] * The number of moles of chain extender includes the reaction terminator.
Example 11 1,6-Hexanediol For 1 mole of high molecular weight diol prepared by mixing polycarbonate (number average molecular weight 2000) and polycaprolactone diol (number average molecular weight 2000) at a weight ratio of 30/70, isophorone diisocyanate and 4 , 4'-dicyclohexylmethane diisocyanate (molar ratio 1:1) was added at a ratio of 2.2 moles, and the mixture was reacted at 100° C. for 9 hours to obtain a urethane prepolymer. After adding methyl ethyl ketone to this to make a prepolymer solution with a concentration of 60% by weight, isophorone diamine was added at a rate of 1.1 mol per mol of polymer diol.
A prepolymer solution in which an extender solution is prepared by dissolving an amine mixed with n-butylamine at a ratio of 0.1 mole in a mixed solvent of methyl ethyl ketone and isopropyl alcohol at a weight ratio of 2:1, and this extender solution is vigorously stirred. Polyurethane solution concentration: 40%, viscosity: 150P
A polyurethane resin solution (40%, 20°C) was obtained. Example 1 Using this polyurethane resin solution
A printing ink composition was prepared in the same manner as above. This printing ink composition was superior to conventional products in terms of dispersibility, adhesion, and durability. Comparative Example 1 300 parts of polytetramethylene glycol with a number average molecular weight of 2000 and 66.7 parts of isophorone diisocyanate were mixed and reacted at 95°C for 10 hours to reduce free NCO%.
obtained 3.44% urethane prepolymer. After adding 244.5 parts of methyl ethyl ketone (MEK) to make a homogeneous solution, the urethane was added to a solution of 23.3 parts of isophoronediamine and 2.36 parts of di-n-butylamine dissolved in a mixed solvent of 226.3 parts of MEK and 117.7 parts of isopropanol. MEK solution of prepolymer
611.2 parts were added dropwise at room temperature. After dropping, raise the temperature to 50℃
The mixture was allowed to react for 3 hours. The viscosity of this polyurethane resin solution was 12,500 cps/20°C/40%. A printing ink composition was prepared in the same manner as in Example 1 using the above polyurethane resin, and the printability and durability were examined and the results are shown in Table 1. Comparative Example 2 300 parts of polybutylene adipate diol with a number average molecular weight of 2000 and 78.6 parts of 4,4'-dicyclohexylmethane diisocyanate were mixed and reacted at 95°C for 10 hours to obtain a urethane prepolymer with a free NCO% of 3.32%. Ta. Next, 244.5 parts of MEK was added to obtain a urethane prepolymer solution with a concentration of 60%, and then 23.3 parts of isophoronediamine and 2.36 parts of di-n-butylamine were dissolved in a mixed solution of 226.3 parts of MEK and 117.7 parts of isopropanol. 631 g of MEK solution of urethane prepolymer was added dropwise to the solution at room temperature. After the dropwise addition, the temperature was raised to 50°C and the mixture was reacted for 3 hours.
The viscosity of this polyurethane resin solution is 13000cps/20
It was ℃/40%. A printing ink composition was prepared using the above polyurethane resin in the same manner as in Example 1, and the printability and durability were examined and the results are summarized in Table 1.

Claims (1)

[Scope of Claims] 1. In a printing ink composition having as a main binder an organic solvent-soluble polyurethane resin obtained by reacting a high molecular weight diol, an organic diisocyanate, and a chain extender, the high molecular weight diol component of the polyurethane resin is a high molecular weight diol containing a polycarbonate diol having a number average molecular weight of 700 to 3000. 2. The printing ink composition according to claim 1, wherein the organic diisocyanate is an alicyclic diisocyanate. 3. The printing ink composition according to claim 1 or 2, wherein the chain extender is an alicyclic diamine. 4. The printing ink composition according to claim 2 or 3, wherein the molar ratio of the hydroxyl group of the high molecular weight diol to the isocyanate group of the organic diisocyanate is in the range of 1:2 to 1:5. 5. The printing ink composition according to claim 4, wherein the polyurethane resin film has a modulus of 20 to 110 kg/cm ² at 100% elongation.