JPH0243275A - Laminate ink composition for heat sterilization - Google Patents

Abstract

PURPOSE:To form an ink composition which has good storage stability and residence stability and does not undergo blocking during storage in a roll of a printing film before laminating by using a mixture of an organic solvent- soluble linear polyurethane resin with a specified blocked isocyanate compound as the principal binder. CONSTITUTION:This laminate ink composition comprises a mixture of an organic solvent-soluble linear polyurethane resin with an isocyanate compound blocked with an oxime or an active methylene compound as the principal binder. As the linear polyurethane resin, one having an MW in the range of 5000-150000 is desirable. Examples of a blocking agent of the blocked isocyanate compound include oximes such as acetone oxime, 2-butanone oxime and cyclohexanone oxime and active methylene compounds such as an acetoacetic ester, dimethyl malonate and acetylacetone. The amount of the blocked isocyanate compound added is about 0.1-50 pts.wt. per 100 pts.wt. linear polyurethane resin (in terms of solid matter).

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a laminating ink composition that is subjected to heat sterilization treatment such as low temperature boil sterilization, high temperature boil sterilization, retort sterilization, and high retort sterilization. .

(Conventional technology) Low temperature boil sterilization, high temperature boil sterilization, retort sterilization.

Heat sterilization treatment such as high-retort sterilization is performed.

Printing ink used in laminating films for packaging materials for food and beverages, pharmaceuticals, medical equipment, etc.

Excellent in lamination processability, boil/retort resistance, oil resistance, etc., low residual solvent, and good adhesion.

The main binder used is a mixture of a linear polyurethane resin soluble in an organic solvent and a polyisocyanate compound. However, since these printing inks have low storage stability, a polyisocyanate compound must be added to the component containing the linear polyurethane resin and mixed immediately before use, which is cumbersome. There are disadvantages such as lack of stability of the remaining meat, and reuse of the remaining meat may be difficult.

For this reason, the present inventors used a blocked isocyanate compound instead of a polyisocyanate compound mainly in the hope that the polyisocyanate compound of the blocked isocyanate compound would dissociate and react during heat sterilization, and improved storage stability and residual properties. We investigated ways to improve meat stability. However, when the blocking agent of the blocked isocyanate compound is phenol or lactam, although storage stability and remaining meat stability are improved, during heat sterilization,
This method has disadvantages in that floating, delamination, or blistering occurs between the films of the laminated film, and blocking occurs when the printed film before lamination is wound up and stored.

(Problem to be solved by the invention) The present invention has good storage stability and remaining meat stability.

A laminating ink composition for heat sterilization that does not cause blocking even when the printed film before lamination is rolled up and stored, and does not cause floating between the laminated films, delamination, or blisters during heat sterilization. It provides:

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a linear polyurethane resin soluble in an organic solvent,
This is a laminating ink composition for heat sterilization, which contains as a main binder a mixture with a blocked isocyanate compound blocked with an oxime or an active methylene compound.

In the present invention, the linear polyurethane resin soluble in an organic solvent is obtained by reacting a polyol, a diisocyanate compound, a chain extender, and/or a terminal blocking agent.

A polyurethane resin that is soluble in organic solvents commonly used in laminating inks, such as toluene, xylene, ketones, esters, and alcohols. Examples of polyols include polyether polyols such as polymers or copolymers such as methylene oxide, propylene oxide, and tetrahydrofuran; ethylene glycol, 1,2-propanediol,
1.3 propanediol, 1,3-butanediol, 1
゜4-Butanediol, neopentyl glycol, bentanediol, hexanediol, octanediol 1
．． Saturated or unsaturated low-molecular polyols such as 4-butylene diol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, sorbitol, pentaerythritol: these low-molecular polyols, adipic acid,
Phthalic acid, isophthalic acid, terephthalic acid, maleic acid,
Polyhydric carboxylic acids such as fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, di-speric acid, azelaic acid, sebacic acid, trimellitic acid, and pyromellitic acid, or their anhydrides, are dehydrated or condensed. Polyester polyols obtained by polymerization; polyester polyol necks obtained by ring-opening polymerization of cyclic ester compounds; polycarbonate polyols; polybutadiene glycols; glycols obtained by adding ethylene oxide or propylene oxide to bisphenol A and so on. Examples of diisocyanate compounds include aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, or mixtures thereof.1 For example, 1.5
- Naphthylene diisocyanate, 4.4'-diphenylmethane diisocyanate 4.4'-diphenyldimethylmethane diisocyanate, 4.4'-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1.3-phenylene diisocyanate, 1°4 -Phenyl diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate.

Hexamethylene diisocyanate 2.2.4-Trimethylhexamethylene diisocyanate, lysine diisocyanate, cyclohexane-1,4-diisocyanate xylylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane 4,4'-diisocyanate, 1,3-bis(methyl isocyanate) Examples include cyclohexane and methylcyclohexane diisocyanate. Ethylene diamine and propylene diamine are used as chain extenders.

Hexamethylenediamine, diethylenetriamine.

In addition to triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, 2-
Amines having a hydroxyl group such as hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine can also be used. Further, as the terminal blocking agent, dialkylamine such as di-n-butylamine can be used.

The organic solvent-soluble linear polyurethane resin used in the present invention is prepared by: (i) reacting the above polyol with a diisocyanate compound in a proportion that the isocyanate groups are in excess to obtain a prepolymer with terminal isocyanate groups; in a suitable solvent.

That is, commonly used as a solvent for printing inks,
Aromatic solvents such as benzene, toluene, and xylene; Ester solvents such as ethyl acetate and butyl acetate; Alcohol solvents such as methanol, ethanol, isopropyl alcohol, and n-butanol; Ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone. ; or a two-step process in which the above polyol, diisocyanate compound 1M extender and/or end-blocker are reacted once in a suitable solvent with a chain extender and/or end-blocker; It is produced by a one-step reaction method. Among these methods, the two-stage method is preferred in order to obtain a uniform linear polyurethane resin. In addition, when producing a linear polyurethane resin by a two-step process, the chain extender and/or end-blocking agent are added to the prepolymer, and the isocyanate groups of the prepolymer/the amino acids of the chain extender and/or end-blocker are It is preferable to carry out the reaction so that the total (equivalence ratio) of the groups is 110.9 to 1.3.

The equivalent ratio of isocyanate groups to amino groups is 1/1.
When it is less than 3, the chain extender and/or terminal blocking agent remain unreacted, which may cause yellowing of the linear polyurethane resin or generation of odor after printing. The molecular weight of the linear polyurethane resin thus obtained is preferably within the range of 5,000 to 150,000. When the molecular weight of the linear polyurethane resin is less than 5,000, the drying properties of the resulting laminating ink composition, the strength and oil resistance of the printed film tend to be low, and
If it exceeds 000, the viscosity of the resulting laminating ink composition tends to be high and the gloss of the printed film tends to be low.

In the present invention, the blocked isocyanate compound is one obtained by reacting almost the entire amount of isocyanate groups of a polyisocyanate compound with a blocking agent.

Examples of the polyisocyanate compound include, in addition to the above diisocyanate compounds, adducts of terminal isocyanate groups obtained by reacting a diisocyanate compound with a polyol.

Further, in the present invention, an oxime or an active methylene compound is used as a blocking agent for the blocked isocyanate compound. As an oxime.

There are acetone oxime, 2-butanone oxime, 3-methyl-2-butanone oxime, 2-hebutanone oxime, cyclohexanone oxime, etc., and active methylene compounds include acetoacetate, malonic acid dimethyl ester, acetylacetone, etc. be. The block isocyanate compound is usually 0.1 to 5 parts by weight per 100 parts by weight of linear polyurethane resin (solid content) soluble in an organic solvent.
It is added and mixed in a proportion of 0 parts by weight, preferably 1 to 30 parts by weight. Addition amount of blocked isocyanate compound is 50
If the amount exceeds parts by weight, the drying properties of the resulting laminating ink composition tend to decrease.

In the present invention, the binder includes a main binder consisting of a mixture of a linear polyurethane resin soluble in an organic solvent and a blocked isocyanate compound blocked with an oxime or an active methylene compound, and, if necessary,
Nitrocellulose, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyamide, acrylic resin, etc. may be blended.

In addition to the above-mentioned binder, the laminating ink composition of the present invention may contain additives such as coloring agents such as pigments, solvents, surfactants for improving the fluidity of the ink and film condition, and waxes, if necessary. It is blended, printed onto various films using methods such as gravure printing and flexographic printing, and dried. The various films that can be printed include cellophane, moisture-proof cellophane, polyethylene, polypropylene, and other olefin resins.

Polyesters such as polyethylene terephthalate and polybutylene terephthalate, and vinyl chloride resins.

Consists of vinylidene chloride resin, styrene resin, vinyl acetate resin, vinyl alcohol resin, polyamide, etc. - Films with or without axial or bidirectional stretching, with or without surface treatments such as corona discharge treatment, low temperature plasma treatment. The drying temperature is usually about 40 to 60°C. On the printed surface of the film printed with the laminating ink composition of the present invention, another film or aluminum foil is attached with or without a urethane-based or modified polyolefin-based adhesive, or an anchor coating agent is applied. Extrusion lamination is carried out with or without intervening to form a laminated film. When an adhesive is used, the drying temperature and sticking temperature of the adhesive are usually around 70°C.

For retort sterilization applications, polyester film/
Laminated films with compositions such as polypropylene film, polyamide film/polypropylene film, polyester film/aluminum foil/polypropylene film are suitable, and for applications that are sterilized by boiling, laminate films with compositions such as polyester film/polyethylene film, polyamide film/polyethylene film, etc. is suitable.

Anchor coating agents include organic titanium, polyisocyanate, polyethyleneimine, and polybutadiene, and extrusion laminated resins include low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene. , ethylene-vinyl acetate copolymers or their saponified products, ethylene-ethyl acrylate copolymers, ethylene-acrylic acid copolymers, polyethylene terephthalate, polyamides, polymethylpentene-1, iomers, and the like.

Extrusion lamination is carried out by extrusion coating the printed surface of the film with the above-mentioned resin which has been heated to 120 to 310 DEG C. and melted, and then immediately cooled by a cooling means such as a cooling roll.

The laminated film obtained in this way.

It is formed into the shape of a bag or other container, filled with food, drinks, medicine, medical equipment, etc., and then heat sterilized. The conditions for heat sterilization are 1.
Usually, 85℃ for 30 minutes for low-temperature boil sterilization, 100℃ for 30 minutes for high-temperature boil sterilization, and 1 for retort sterilization.
20-130℃ for 30 minutes, 14 for high retort sterilization
The temperature is 0 to 145°C for about 10 minutes.

(Example) The present invention will be explained below with reference to Examples. In the examples, 2 parts means parts by weight, and 9% means % by weight.

Synthesis Example 1 228 parts of polyester diol with an average molecular weight of 2000 obtained by reacting adipic acid and 1,4-butanediol, 51 parts of isophorone diisocyanate, and 194 parts of methyl ethyl ketone were reacted at 75°C for 6 hours to form a terminal isocyanate prepolymer. 473 parts of solvent solution were obtained.

18 parts of isophoronediamine, 3. di-n-butylamine.
0 parts of methyl ethyl ketone and 220 parts of isopropyl alcohol were gradually added at room temperature to a mixture of 286 parts of methyl ethyl ketone and 220 parts of isopropyl alcohol.
A linear polyurethane resin solution A of 0% and a viscosity of 6P at 25° C. was obtained.

Synthesis examples 2 to 4 1 In the same manner as in Synthesis Example 1 using the raw materials shown in Table 1.

A linear polyurethane resin solution BD was obtained.

Table 1 * Polyester diol with an average molecular weight of 2000 obtained by reacting adipic acid and 1,4-butadiol.

This polyester diol has an average molecular weight of 2000 and is obtained by reacting adipic acid with 1,2-propylene glycol.

Hon Hon Umbrella Polycaprolactone polyol with an average molecular weight of 2000.

Polyoxypropylene glycol with an average molecular weight of 2000.

Viscosity: Measured at 25°C.

Example 1 Titanium white 30 parts Linear polyurethane resin solution A 50 parts Toluene 7 parts Methyl ethyl ketone 7 parts Isopropyl alcohol 6 parts Trimethylolpropane 3 parts Hexamethylene diisocyanate per mole
After blocking the triisocyanate adduct obtained by reacting the molar ratio with diethyl malonate,
2.3 parts After kneading the mixture with the above composition in a ball mill for 20 hours, 30% methyl ethyl ketone,
A mixed solvent consisting of 40% toluene and 30% isopropyl alcohol was added, and the Zahn Kafpoule was heated at 25°C.
The viscosity measured in step 3 was adjusted to 18 seconds. The returned laminating ink was printed on the corona discharge treated surface of a 15 μm thick corona discharge treated nylon film "Emblem" (manufactured by Unitika, trade name) using a 9-plate gravure plate with a depth of 35 μm and dried.

A mixed solvent consisting of 30% methyl ethyl ketone, 40% toluene and 30% isopropyl alcohol was added to the remaining thickness of the laminating ink after printing, and the viscosity was readjusted to 18 seconds as measured with a Zahn cup 3 at 25°C. Table 2 shows the results of evaluating the viscosity change rate and fading stability of the viscosity readjusted product of the laminate ink residue before and after storage when stored at 40°C for one week. The rate of change in viscosity of the viscosity readjusted product was calculated according to the 9th equation: The calculation result was less than 080.5.

x: Displayed as 1.0 or more. To evaluate the fading stability of the viscosity-adjusted product of the remaining laminating ink before and after storage, the viscosity-adjusted product of the remaining laminate ink before storage was coated onto a film using a bar coater - Ma 6 and dried. As a standard sample, the viscosity of the viscosity of the remaining laminated ink after storage was adjusted again so that the measured viscosity with Zahn Cup Magnetic 3 was 18 seconds, and a sample was prepared in the same manner as the standard sample. The difference between the color of the sample and the color of the sample was visually observed. What are the evaluation results?

○: No difference in color, △: Slight fading, but no practical problem. ×: Displayed as a faded layer.

On the other hand, overlap the two printed films obtained.

After applying a load of 500 g/aa and leaving it at 40° C. for 24 hours, the peeling resistance when the printed film was peeled off and the presence or absence of peeling of the laminating ink were evaluated as blocking resistance. The evaluation results are shown in Table 2. In addition.

The evaluation results were as follows: ◯: Peeling was possible with low resistance, and there was no peeling of the laminating ink. Δ: There was some resistance during peeling, but the laminating ink did not peel off and there was no practical problem. ×
: The resistance during peeling was large and the laminating ink peeled off.

In addition, two-component polyurethane adhesives "Atocoat AD900J and "Atocoat RT-5J" were applied to the resulting printed surface.
(all manufactured by Toyo Morton, trade name), dried, and a medium density polyethylene film rNB-IJ (manufactured by Tamabori ■) with a thickness of 60 μm was applied to the coated surface.

(trade name) was laminated together and aged at 40° C. for 2 days to obtain a laminate film. The two obtained laminate films were stacked so that the medium-density polyethylene film surfaces overlapped, and the periphery of the two films was heat-sealed to form a bag shape.
Changes in appearance when filled with a mixture of salad oil/vinegar/water = 1/1/1 (weight ratio) and boil sterilized at 100°C for 30 minutes and retort sterilized at 120°C for 30 minutes Changes in appearance over time were visually evaluated. The evaluation results are shown in Table 2.

The evaluation results were expressed as ◯: no change, ×: blistering occurred on the entire surface, or delamination occurred on the entire surface.

Examples 2 to 4 Instead of linear polyurethane resin solution A, linear polyurethane resin solution B was used in Example 2, linear polyurethane resin solution C was used in Example 3, and linear polyurethane resin was used in Example 4. Laminating inks were obtained in the same manner as in Example 1 except that the respective solutions were used, and the evaluation results are shown in Table 2.

Example 5 Instead of 2.3 parts of the blocked isocyanate compound used in Example 2, the triisocyanate adduct used as the raw material for the blocked isocyanate compound in Example 1 was blocked with methyl ethyl ketone oxime to obtain a blocked isocyanate compound 2. Same as Example 2 except that 4 parts were used.

Table 2 shows the results of obtaining and evaluating laminating inks.

Examples 6 to 10 Instead of 2.3 parts of the blocked isocyanate compound used in Example 2, a triisocyanate adduct obtained by reacting 1 mol of trimethylolpropane with 3 mol of isophorone diisocyanate was reacted with methyl ethyl ketone oxime. The blocked isocyanate compound was added to 0.02 parts in Example 6, 0.06 parts in Example 7, 0.6 parts in Example 8, 3.0 parts in Example 9, and 3.0 parts in Example 10. In addition, 0 parts of dibutyltin dilaurate were used per 100 parts of the blocked isocyanate compound.
．． A laminating ink was obtained in the same manner as in Example 2 except that 5 parts were added.

Table 2 shows the results of the evaluation.

Comparative Example 1 A laminating ink was obtained in the same manner as in Example 2 except that the blocked isocyanate compound was not added.

The evaluation results are shown in Table 2.

Comparative Example 2 Example 2 except that the triisocyanate adduct used as the raw material for the blocked isocyanate compound in Example 1 was used instead of the blocked isocyanate compound.
A laminating ink was obtained in the same manner as above, and the evaluation results are shown in Table 2.

Comparative Example 3 Instead of 2.3 parts of the blocked isocyanate compound used in Example 2, 2.4 parts of the blocked isocyanate compound obtained by blocking the triisocyanate adduct used as a raw material for the blocked isocyanate compound in Example 1 with caprolactam. A laminating ink was obtained in the same manner as in Example 2, except that the sample was used, and the evaluation results are shown in Table 2.

Comparative Example 4 Instead of 2.3 parts of the blocked isocyanate compound used in Example 2, 3.0 parts of the blocked isocyanate compound obtained by blocking the triisocyanate adduct used as a raw material for the blocked isocyanate compound in Example 1 with phenol. Example 2 except that part was used.
A laminating ink was obtained in the same manner as above, and the evaluation results are shown in Table 2.

(Hereinafter, blank space) [Effects of the invention] According to the present invention, storage stability and remaining meat stability are good,
A laminating ink composition for heat sterilization that does not cause blocking even when the printing film before lamination is rolled up and stored, and does not cause floating between the films of the laminate, delamination, or blistering during heat sterilization. Now you can get it.

Claims (1)

[Claims] 1. A laminating ink composition for heat sterilization, which contains as a main binder a mixture of a linear polyurethane resin soluble in an organic solvent and an isocyanate compound blocked with an oxime or an active methylene compound.