JP3446477B2 - Polyurethane resin for printing ink and printing ink using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polypropylene (hereinafter abbreviated as PP) film, a polyester (hereinafter
The present invention relates to a polyurethane resin for printing ink, which shows good adhesion to both a PET film and a nylon (hereinafter abbreviated as NY) film, and a printing ink using the same as a binder.

[0002]

2. Description of the Related Art Generally, oriented polypropylene (hereinafter referred to as O
In the case of printing on a film (abbreviated as PP), an amorphous resin having a polar group such as chlorinated polypropylene resin, vinyl chloride resin, and cyclized rubber is anchor-coated as an adhesiveness-imparting agent, and then a polyurethane resin is used. Print surface printing ink with acrylic resin as binder. Alternatively, using a polyamide resin having adhesiveness but releasability and nitrification cotton having crystallinity as a binder, a surface printing ink having both adhesiveness and winding blocking resistance is directly printed on an OPP film. . In order to improve the durability of the coating film and deal with the suitability for post-processing, the surface printing ink using a polyamide resin and a nitrified cotton as a binder may be further combined with an acrylic resin or a vinyl chloride / vinyl chloride resin.

On the other hand, as the back-printing ink, an ink in which a resin such as a chlorinated polypropylene resin, vinyl chloride resin, and cyclized rubber is used together is used. However, the above-mentioned front-side printing ink and back-side printing ink have insufficient adhesion to the PET film and NY film. Especially, regarding the back-side printing ink, the adhesive and the back-side printing ink are used during boiling at high temperature or during retort processing. There is a problem that peeling occurs at the interface. The adhesiveness to the PET film can be easily improved by using a polyester resin together, but there is a drawback that the heat resistance is inferior.

In addition, if the adhesiveness to PET film and NY film is improved by increasing the amount of adhesive components such as chlorinated polypropylene resin, vinyl chloride resin, cyclized rubber, etc., heat resistance and chemical resistance The sex becomes worse. Chemical resistance is improved by using a cross-linking system that utilizes the reaction between isocyanate groups and hydroxyl groups or the reaction between epoxy groups and amino groups, but there is the drawback that the adhesiveness is limited by curing strain. From this point of view, polyurethane resins with a flexible molecular main chain and good chemical resistance are drawing attention, but conventional printing inks using polyurethane resins as binders are used for boiling and retorting at high temperatures. There was a problem that it turned yellow during processing and bleeding with the adhesive when laminating with a non-solvent type adhesive.

[0005]

The object of the present invention is to provide an OP
Polyurethane resin for printing ink, which has excellent adhesiveness to any of P film, PET film and NY film and has excellent heat resistance, and polyethylene by extrusion using polyethyleneimine adhesive on printed matter. When the laminate is used, the strength of the laminate is stable, there is no bleeding when laminating with a non-solvent type adhesive, it has excellent re-dissolvability, and it has good printability for various plastic films. To provide ink.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have made a polyester adipate having a number average molecular weight of about 2000, a polyester polyol such as 3-methylpentylene adipate, a tertiary amine having two or more hydroxyl groups, an organic diisocyanate and an amine-based compound. When a chain extender is reacted to synthesize a polyurethane resin, a low molecular weight glycol or polyester polyol is used in combination to produce OPP.
It was found that a polyurethane resin having excellent adhesiveness to films, PET films and NY films can be obtained,
The present invention has been completed.

Since the printing ink using the above-mentioned polyurethane resin as a binder does not cause distortion of the ink film, the inventors of the present invention have made a laminate when polyethylene is extruded and laminated on a printed matter by using a polyethyleneimine-based adhesive. It has been found that the strength of the product is stable and bleeding does not occur during laminating with a non-solvent type adhesive. Further, it has been found that the polyurethane resin having an amine value in the range of 0.2 to 7.0 has excellent heat resistance because the content of unreacted tertiary amine is small. Furthermore, the present inventors have found that the dispersibility of the pigment is improved by introducing a tertiary nitrogen into the main chain of the polyurethane resin and introducing a hydroxyl group into the molecular side chain.

That is, the present invention provides (A) a polyester polyol having a number average molecular weight of 1500 to 3400, which comprises a dibasic acid or acid anhydride and an alkanediol having a carbon number of 3 to 10, and (B) a number average molecular weight of 50 to 500. Of the glycol or polyester polyol, (C) a tertiary amine having two or more hydroxyl groups, (D) an organic diisocyanate, and (E) an amine chain extender. The present invention also relates to the above-mentioned polyurethane resin for printing ink, which has an amine value in the range of 0.2 to 7.0.

The present invention also relates to the above polyurethane resin for printing ink, wherein the (E) amine chain extender has a hydroxyl group and the hydroxyl value is in the range of 0.1 to 1.0. The present invention also relates to printing ink using the polyurethane resin as a binder. Further, the present invention is
The printing ink further comprises a polyisocyanate crosslinking agent.

[0010]

DETAILED DESCRIPTION OF THE INVENTION

(A) Number average molecular weight of 1500 to 3400 composed of dibasic acid or acid anhydride and alkanediol having 3 to 10 carbon atoms
Examples of the polyester polyol include propylene adipate, propylene sebacate, methylpentylene adipate, hexamethylene diethyl carbonate, and 3-methylcaprolactam adipate. Examples of the (B) glycol or polyester polyol having a number average molecular weight of 50 to 500 include tetrapropylene glycol, propylene oxide-added 3-methylpentyl alcohol, dipropylene adipate, and dipropylene sebacate.

The (B) glycol or polyester polyol having a number average molecular weight of 50 to 500 is a polyester polyol having a number average molecular weight of 1500 to 3400, which comprises (A) a dibasic acid or acid anhydride and an alkanediol having 3 to 10 carbon atoms. 0.5 to 5% by weight, and even 0.5
It is preferably used in the range of 1 to 1% by weight. When the amount of (B) used is less than 0.5% by weight of (A), the heat resistance of the resulting polyurethane resin is insufficient. On the other hand, when it exceeds 5% by weight, the water resistance and hot water resistance of the resulting polyurethane resin are deteriorated.

The (C) tertiary amine having two or more hydroxyl groups improves the adhesiveness of the polyurethane resin obtained by introducing tertiary nitrogen into the main chain to the OPP film, and the molecular weight of the obtained polyurethane resin. Used to increase. Examples of the tertiary amine (C) having two or more hydroxyl groups include methyldiethanolamine, phenyldiisopropanolamine, phenyldiethanolamine and phenyldimethanolamine.

Examples of the organic diisocyanate (D) include tolylene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate, tetramethylene xylene diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate.

(E) Among amine chain extenders, amine chain extenders having no hydroxyl group include isophoronediamine, N, N-diaminopropylamine, ethylenediamine,
Examples include triethylenediamine. In addition, examples of the amine chain extender having a hydroxyl group include aminoethylethanolamine. It is preferable to use an amine chain extender having a hydroxyl group because the resulting polyurethane resin has improved adhesiveness and increased adhesive strength. The amount of the amine-based chain extender having a hydroxyl group used is preferably adjusted so that the resulting polyurethane resin has a hydroxyl value in the range of 0.1 to 1.0. A polyurethane resin having a hydroxyl value of more than 1.0 has poor water resistance and hot water adhesiveness. Also,
A polyurethane resin having a hydroxyl value of less than 0.1 has insufficient adhesive strength.

In the polyurethane resin for printing ink of the present invention, (A), (B), (C) and (D) are reacted to synthesize a prepolymer, and then (E) and, if necessary, a terminal terminating agent. It is synthesized by reacting. Examples of the terminal terminator include dibutylamine, diethylamine, dimethylamine and the like. When (D) having high reactivity is used, if (A), (B), (C) and (D) are reacted at once, insoluble butts are produced,
It is preferable to add (C) after reacting (A), (B) and (D). When (C) is added in the second step in the prepolymer synthesis process, it acts as a chain extender for the prepolymer synthesized in the first step, and the molecular weight of the prepolymer increases, so that the molecular weight of the resulting polyurethane resin increases. The desired molecular weight can be adjusted.

When synthesizing the polyurethane resin for printing ink of the present invention, the ratio of isocyanate group / hydroxyl group is 1.
It is preferably 6 to 1.8. Isocyanate group /
When the ratio of the hydroxyl groups exceeds 1.8, the resulting polyurethane resin has increased urea bonds, and thus the solubility in the non-aromatic organic solvent decreases, and the binder of the printing ink using the non-aromatic organic solvent as the solvent. When used as turbidity, turbidity and spots occur. The lump of printing ink causes clogging of the gravure plate, which causes a problem in image reproducibility. On the other hand, when it is less than 1.6, the molecular weight of the obtained polyurethane resin becomes low, and therefore, when polyethylene is extruded and laminated on the printed matter by using a polyethyleneimine-based adhesive, the strength of the laminated matter is decreased. Ink bleeds easily when laminating with a non-solvent type adhesive.

The polyurethane resin for printing inks of the present invention is presumed to be a mixture of a low molecular weight polyurethane resin having a weight average molecular weight of 2000 to 4000 and a high molecular weight polyurethane resin having a weight average molecular weight of 60,000 to 75,000. The low molecular weight polyurethane resin acts as a plasticizer for the high molecular weight polyurethane resin, imparts flexibility to the ink film, promotes the wetting of the pigment and also acts as a pigment dispersant, and has the effect of eliminating the distortion of the ink film. is there.

The amine value of the polyurethane resin for printing ink of the present invention is preferably in the range of 0.2 to 7.0. Polyurethane resin with amine value over 7.0 is
Since it contains unreacted amine, it has poor heat resistance, causing yellowing and deterioration of physical properties. Yellowing is noticeable when the polyurethane resin is used as a binder for white printing ink.

The polyurethane resin for printing inks of the present invention has excellent adhesiveness to various plastic films and is therefore suitable as a binder for printing inks. Further, the polyurethane resin for printing ink of the present invention,
Since it also dissolves in a non-aromatic organic solvent, it is also suitable as a binder for a printing ink using a non-aromatic organic solvent as a solvent. Boil which requires heat treatment for printing ink using the polyurethane resin for printing ink of the present invention as a binder,
When used for retort printing, it is preferable to use a polyisocyanate crosslinking agent together.

[0020]

EXAMPLES The present invention will be described in detail below based on examples. In the examples, parts and% represent parts by weight and% by weight, respectively.

Example 1 A propylene adipate having a number average molecular weight of 1873 was placed in a separate type flask equipped with a stirrer, a thermometer, a cooling tube, a dropping funnel, and a nitrogen introducing tube.
Charge 9.70 parts, 6.29 parts of propylene adipate having a number average molecular weight of 300 to 500 and 51.95 parts of diphenylmethane diisocyanate (NCO / OH = 1.8),
Heated at 80 ° C. for 1 hour. Then, 1.04 parts of methyldiethanolamine was added, and the mixture was stirred at 80 ° C. for 1.5 hours and then diluted with 215 parts of ethyl acetate,
A prepolymer A solution was obtained. Next, in a separate type flask equipped with a stirrer, a thermometer, a condenser, a dropping funnel, 11.77 parts of isophoronediamine, 0.80 part of aminoethylethanolamine, 2.16 parts of dibutylamine, 210 parts of isopropyl alcohol, acetic acid. 150 parts of ethyl was precisely weighed and mixed. The temperature of the flask was set to 30 ° C., and 483.98 parts of the prepolymer A solution was added dropwise over 30 minutes. After completion of the dropping, the temperature of the flask was kept at 75 ° C. and stirring was continued for 2 hours to complete the reaction. After that, ethyl acetate 1
Add 10 parts, solid content 30%, viscosity 1700 cps, amine value 3.06, hydroxyl value 0.4, weight average molecular weight 68
000 polyurethane resin solutions were obtained.

(Example 2) In a flask similar to that of Example 1, 219.62 parts of 3-methylpentylene adipate having a number average molecular weight of 2000 and 10.98 of diethylene glycol were placed.
And 46.17 parts of diphenylmethane diisocyanate were charged (NCO / OH = 1.6) and heated at 80 ° C. for 1 hour. Then phenyldiisopropanolamine 1.
After adding 82 parts and stirring at 80 degreeC for 1.5 hours, 210 parts of ethyl acetate was added and diluted, and the prepolymer B solution was obtained. Next, in a separate flask equipped with a stirrer, a thermometer, a cooling tube, and a dropping funnel, 7.84 parts of isophoronediamine, 0.80 part of aminoethylethanolamine, 2.16 parts of dibutylamine, 210 parts of isopropyl alcohol, acetic acid. 150 parts of ethyl was precisely weighed and mixed. The temperature of the flask was set to 30 ° C., and 488.59 parts of the prepolymer B solution was added dropwise over 30 minutes. After completion of the dropping, the temperature of the flask was kept at 75 ° C. and stirring was continued for 2 hours to complete the reaction. Thereafter, 125 parts of ethyl acetate was added to the mixture to give a solid content of 29%, a viscosity of 440 cps and an amine value of 2.7.
6, a polyurethane resin solution having a hydroxyl value of 0.5 and a weight average molecular weight of 66,000 was obtained.

(Example 3) A propylene sebacate 3 having a number average molecular weight of 3000 was placed in the same flask as in Example 1.
Charged 29.46 parts, diethylene glycol 16.47 parts and isophorone diisocyanate 40.95 parts (NC
O / OH = 1.6), heated at 80 ° C. for 1 hour. Then, 1.04 parts of methyldiethanolamine was added, and 8
After stirring at 0 ° C. for 1.5 hours, 210 parts of ethyl acetate was added for dilution to obtain a prepolymer C solution.
Next, in a separate flask equipped with a stirrer, a thermometer, a cooling tube, and a dropping funnel, 8.46 parts of isophoronediamine was added.
Parts, aminoethylethanolamine 0.80 parts, dibutylamine 2.16 parts, isopropyl alcohol 210
And 150 parts of ethyl acetate were precisely weighed and mixed. The temperature of the flask was set to 30 ° C., and the prepolymer C solution 597.9 was added.
Two parts were added dropwise over 30 minutes. After completion of the dropping, the temperature of the flask was kept at 75 ° C. and stirring was continued for 2 hours to complete the reaction. Then, 120 parts of ethyl acetate was added to give a solid content of 29.
A polyurethane resin solution having a viscosity of 5%, a viscosity of 800 cps, an amine value of 3.43, a hydroxyl value of 0.8, and a weight average molecular weight of 59000 was obtained.

(Example 4) A propylene adipate 32 having a number average molecular weight of 3000 was placed in the same flask as in Example 1.
9.43 parts, diethylene glycol 16.47 parts and tetramethylene xylene diisocyanate 50.65 parts were charged (NCO / OH = 1.8) and heated at 80 ° C. for 1 hour. Then phenyldiisopropanolamine 1.8
After adding 2 parts and stirring at 80 degreeC for 2 hours, 210 parts of ethyl acetate was added and diluted, and the prepolymer D solution was obtained. Next, in a separate type flask equipped with a stirrer, a thermometer, a cooling tube, and a dropping funnel, 12.63 parts of isophoronediamine, aminoethylethanolamine1.
60 parts, dibutylamine 2.16 parts, isopropyl alcohol 210 parts, and ethyl acetate 150 parts were precisely weighed and mixed. The temperature of the flask was set to 30 ° C., and 608.37 parts of the prepolymer D solution was added dropwise over 30 minutes. After completion of the dropping, the temperature of the flask was kept at 75 ° C. and stirring was continued for 2 hours to complete the reaction. Thereafter, 125 parts of ethyl acetate was added to the mixture, solid content 29.0%, viscosity 1800 cps, amine value 3.03, hydroxyl value 0.8, weight average molecular weight 62000.
A polyurethane resin solution of

Comparative Example 1 A propylene adipate 23 having a number average molecular weight of 2000 was placed in the same flask as in Example 1.
0.70 parts and diphenylmethane diisocyanate 51.
Charge 95 parts (NCO / OH = 1.9), 1 at 80 ° C
Heated for hours. Then methyldiethanolamine 1.
After adding 04 parts and stirring at 80 ° C. for 2 hours, 210 parts of ethyl acetate was added to dilute, but the obtained prepolymer solution contained fine insoluble matter, which caused chain length reaction. Was not suitable.

(Comparative Example 2) A propylene adipate 21 having a number average molecular weight of 2000 was placed in the same flask as in Example 1.
5.99 parts and diphenylmethane diisocyanate 49.
Charge 11 parts (NCO / OH = 1.7), 1 at 80 ° C
Heated for hours. Then methyldiethanolamine 1.
After adding 04 parts and stirring at 80 degreeC over 30 minutes, 210 parts ethyl acetate was added and diluted, and the prepolymer E solution was obtained. Next, in a separate type flask equipped with a stirrer, a thermometer, a cooling tube, and a dropping funnel, 11.77 parts of isophoronediamine, and aminoethylethanolamine.
80 parts, dibutylamine 2.16 parts, isopropyl alcohol 210 parts, and ethyl acetate 150 parts were precisely weighed and mixed. The temperature of the flask was set to 30 ° C., and 476.14 parts of the prepolymer E solution was added dropwise over 30 minutes. After completion of the dropping, the temperature of the flask was kept at 75 ° C. and stirring was continued for 2 hours to complete the reaction. Then, 110 parts of ethyl acetate was added to the mixture to obtain a solid content of 29.8%, a viscosity of 1080 cps, an amine value of 8.65, a hydroxyl value of 0.5, and a weight average molecular weight of 42,000.
A polyurethane resin solution of

Comparative Example 3 A propylene adipate 20 having a number average molecular weight of 2000 was placed in the same flask as in Example 1.
Charge 9.70 parts, 6.29 parts of propylene adipate having a number average molecular weight of 300 to 500 and 51.95 parts of diphenylmethane diisocyanate (NCO / OH = 1.8),
Heated at 80 ° C. for 1.5 hours. Then ethyl acetate 21
0 part was added and diluted to obtain a prepolymer F solution. Next, in a separate type flask equipped with a stirrer, a thermometer, a cooling tube, and a dropping funnel, 7.84 parts of isophoronediamine,
Aminoethylethanolamine 0.80 parts, dibutylamine 2.16 parts, isopropyl alcohol 210 parts, and ethyl acetate 150 parts were precisely weighed and mixed. The temperature of the flask was set to 30 ° C., and 477.94 parts of the prepolymer F solution was added dropwise over 30 minutes. After completion of the dropping, the temperature of the flask was kept at 75 ° C. and stirring was continued for 2 hours to complete the reaction. Then, 125 parts of ethyl acetate was added to the solid content 29.0%,
Viscosity 1800 cps, amine value 0.8, hydroxyl value 0.
A polyurethane resin solution having a weight average molecular weight of 38,000 was obtained.

An ink was prepared by the following method using the polyurethane resin solutions obtained in Examples 1 to 4 and Comparative Examples 2 and 3, and the obtained ink was printed on an OPP film under the following printing conditions. [Preparation of White Laminate Ink] Titanium White 30.0 parts Polyurethane resin solution 20.0 parts Methyl ethyl ketone 15.0 parts The mixture of the above composition was dispersed and then diluted with the following formulation. The above mixture 65.0 parts Polyurethane resin solution 14.5 parts Dispersant 1.5 parts Methyl ethyl ketone 18.8 parts Wax 0.2 parts [Printing conditions] Printing machine; Gravure monochromatic printing machine Printing viscosity; 15-16 with Zahn cup # 3 Adjusted with methyl ethyl ketone per second Printing speed: 40m / min

After applying a polyethyleneimine-based anchor coating agent to the ink surface of the obtained printed matter, a polyethylene film was attached using molten polyethylene as an adhesive, and the laminate strength was measured 5 times by the following method. I calculated the average. Further, a non-solvent type adhesive consisting of polyester polyol and isocyanate was applied to the ink surface of the obtained printed matter, and the presence or absence of bleeding of the ink was visually evaluated. In addition, the obtained printed matter is 100
After heating at 0 ° C for 30 minutes, the presence or absence of yellowing was visually evaluated. The results are shown in Table 1. [Laminate strength measurement conditions] Measuring instrument; "Tensilon" manufactured by Toyo Seiki Co., Ltd. Pulling speed; 30 cm / min Peeling angle; 90 degrees (T-type peeling)

[0030]

[Table 1]

Two parts of a polyisocyanate crosslinking agent was added to 100 parts of the obtained ink to prepare a two-component printing ink, and the obtained ink was printed on a NY film and a PET film under the above printing conditions. . After printing a polyurethane adhesive on the ink surface of the obtained printed matter and drying it, a medium-density polyethylene film having a thickness of 80 mm is dry-laminated on the printed surface, and the lamination strength is measured 5 times by the above method, and the average. I asked. In addition, 5 bags were prepared by heat-sealing the obtained laminated film with the polyethylene film side being the inside, and the obtained bag body had salad oil / vinegar / water = 1/1/1 (weight ratio). After the mixture was filled and boiled at 100 ° C. for 30 minutes, the appearance of the bag was visually evaluated (∘: no abnormality was observed in all five bags. Δ:
Delamination was observed in a few bags and blisters occurred.
X: Delamination was observed in all 5 bags, and blisters occurred. ), A boil test was performed. The results are shown in Table 2.

[0032]

[Table 2]

[0033]

EFFECTS OF THE INVENTION According to the present invention, the adhesiveness to various plastic films is good, and the strength of the laminate is stable when polyethylene is extruded and laminated on the printed matter by using a polyethyleneimine adhesive. Printing inks that do not cause bleeding during lamination using a non-solvent type adhesive have become available.

Claims (5)

(57) [Claims] 1. A dibasic acid or acid anhydride (A) and a carbon number of 3 to 3.
Number average molecular weight of 150 consisting of 10 alkanediols
0-3400 polyester polyol, (B) glycol or polyester polyol having a number average molecular weight of 50-500, (C) tertiary amine having two or more hydroxyl groups,
A polyurethane resin for printing ink, which is obtained by reacting (D) an organic diisocyanate and (E) an amine chain extender. 2. The polyurethane resin for printing ink according to claim 1, wherein the amine value is in the range of 0.2 to 7.0. 3. The amine chain extender (E) has a hydroxyl group,
The hydroxyl value is in the range of 0.1 to 1.0, and the polyurethane resin for printing ink according to claim 1 or 2. 4. A printing ink containing the polyurethane resin according to any one of claims 1 to 3 as a binder. 5. The printing ink according to claim 4, further comprising a polyisocyanate crosslinking agent.