JPH07113099B2 - Laminate ink composition for heat sterilization - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a laminate ink composition which is subjected to heat sterilization treatment such as low temperature boil sterilization, high temperature boil sterilization, retort sterilization, and high retort sterilization. .

(Conventional technology) Food and drink products that are subjected to heat sterilization treatment such as low temperature boil sterilization, high temperature boil sterilization, retort sterilization, and high retort sterilization,
As a printing ink used for laminating films for packaging materials such as pharmaceuticals and medical equipment, it has excellent laminating processability, resistance to boil / retort, oil resistance, etc., little residual solvent, and good adhesion to organic solvents. A mixture containing a soluble linear polyurethane resin and a polyisocyanate compound as a main binder is used. However, since these printing inks have low storage stability, they must be mixed with a polyisocyanate compound to a component containing a linear polyurethane resin immediately before use, which is complicated. There was a defect that it was difficult to reuse.

Therefore, the inventors of the present invention mainly use the blocked isocyanate compound instead of the polyisocyanate compound in the expectation that the polyisocyanate compound of the blocked isocyanate compound will dissociate and react during heat sterilization. Considered to improve meat stability. However, when the blocking agent of the blocked isocyanate compound is phenol or lactam, the storage stability and the residual meat stability are improved, but during heat sterilization, floating of the laminate film between films, delamination, blister, etc. may occur. As it happens
There is a drawback that blocking occurs when the printed film before lamination is wound and stored.

(Problems to be Solved by the Invention) The present invention has good storage stability and residual thickness stability, does not cause blocking even when the printed film before laminating is wound and stored, and is a laminated film during heat sterilization. The present invention provides a laminate ink composition for heat sterilization treatment which does not cause floating between films, delamination or blisters.

[Structure of Invention]

(Means for Solving the Problem) The present invention relates to a linear polyurethane resin soluble in an organic solvent,
A laminate ink composition for heat sterilization treatment, which comprises a mixture with an oxime or a blocked isocyanate compound blocked with an active methylene compound as a main binder.

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,
It is a polyurethane resin that is soluble in organic solvents such as toluene, xylene, ketones, esters, and alcohols that are commonly used in laminating inks. As the polyol, polyether polyols of polymers or copolymers of methylene oxide, propylene oxide, tetrahydrofuran, etc .; ethylene glycol, 1,2-propanediol, 1,3
-Propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, hexanediol, octanediol 1,4-butylenediol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerin, tri Saturated or unsaturated low molecular weight polyols such as methylolpropane, sorbitol, pentaerythritol; these low molecular weight polyholes and adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid Polyester polyols obtained by dehydration condensation or polymerization of polycarboxylic acids such as carboxylic acid, malonic acid, glutaric acid, pimelic acid, speric acid, azelaic acid, sebacic acid, trimellitic acid and pyromellitic acid or their anhydrides Polyester polyols obtained by ring-opening polymerization of cyclic ester compounds; polycarbonate polyols; polybutadiene glycols;
Examples include glycols obtained by adding ethylene oxide or propylene oxide to bisphenol A. Examples of the diisocyanate compound include aromatic diisocyanate, aliphatic diisocyanate, alicyclic diisocyanate, and a mixture thereof, such as 1,5-naphthylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethyl. Methane diisocyanate, 4,4'-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexa Methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, a Diisocyanate,
Dicyclohexylmethane-4,4'-diisocyanate, 1,
Examples include 3-bis (isocyanatomethyl) cyclohexane and methylcyclohexane diisocyanate. As chain extenders, ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine,
In addition to triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylenediamine, di-2-hydroxypropylethylenediamine, di- Amines having a hydroxyl group such as 2-hydroxypropylethylenediamine can also be used. Further, a dialkylamine such as di-n-butylamine can be used as the terminal blocking agent.

The linear polyurethane resin soluble in the organic solvent used in the present invention is obtained by reacting the above-mentioned polyol and diisocyanate compound at a ratio such that the isocyanate group becomes excessive to obtain a prepolymer of a terminal isocyanate group, Aromatic solvents such as benzene, toluene, xylene, etc., which are usually used as solvents for printing inks; ester solvents such as ethyl acetate, butyl acetate; methanol, ethanol, isopropyl alcohol, n-butanol, etc. Alcohol-based solvent; ketone-based solvent such as acetone, methyl ethyl ketone, methyl isobutyl ketone; or a two-step method of reacting with a chain extender and / or a terminal blocking agent in a mixture thereof, or the above polyol, diisocyanate compound, Chain extender Manufactured by beauty (or) one-step method of reacting once the terminal blocking agent in a suitable solvent. Among these methods, the two-step method is preferable to obtain a uniform linear polyurethane resin. Also,
When a linear polyurethane resin is produced by a two-step method, the chain extender and / or the end-capping agent is added to the prepolymer, and the isocyanate group / chain extender of the prepolymer and / or the amino group of the end-capping agent is added to the prepolymer. The total (equivalent ratio) is 1 /
It is preferable to react so that the ratio becomes 0.9 to 1.3. When the equivalent ratio of the isocyanate group and the amino group is less than 1 / 1.3, the chain extender and / or the terminal blocking agent remain unreacted, the linear polyurethane resin turns yellow, and the odor after printing It may occur. The molecular weight of the linear polyurethane resin thus obtained is 5000
It is preferably within the range of ˜150,000. When the molecular weight of the linear polyurethane resin is less than 5,000, the drying properties of the resulting laminated ink composition, the strength of the printed film and the oil resistance tend to be low, and when it exceeds 150,000,
The viscosity of the resulting laminated 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 obtained by reacting almost all the isocyanate groups of the polyisocyanate compound with a blocking agent, and as the polyisocyanate compound, other than the diisocyanate compound,
Examples thereof include an adduct of a terminal isocyanate group obtained by reacting a diisocyanate compound with a polyol.

Further, in the present invention, an oxime or an active methylene compound is used as the blocking agent for the blocked isocyanate compound. The oximes include acetone oxime, 2-butanone oxime, 3-methyl-2-butanone oxime, 2-heptanone oxime, and cyclohexanone oxime. Active methylene compounds include acetoacetic acid ester, malonic acid dimethyl ester, and acetylacetone. There is. The blocked isocyanate compound is usually 0.1 to 50 parts by weight, preferably 1 to 30 parts by weight with respect to 100 parts by weight of a linear polyurethane resin (solid content) soluble in an organic solvent.
It is added and mixed in a ratio of parts by weight. If the amount of the blocked isocyanate compound added exceeds 50 parts by weight, the drying property of the obtained laminated ink composition tends to be low.

In the present invention, the binder is a main binder comprising 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 and the like may be blended.

In the laminated ink composition of the present invention, in addition to the above-mentioned binder, if necessary, a colorant such as a pigment, a solvent, a surfactant for improving the fluidity of the ink or a film state, an additive such as a wax are appropriately added. It is mixed, printed on various films by methods such as gravure printing and flexographic printing, and dried. The various printed films include cellophane,
It consists of moisture-proof cellophane, olefin resin such as polyethylene and polypropylene, polyester such as polyethylene terephthalate and polybutylene terephthalate, vinyl chloride resin, vinylidene chloride resin, styrene resin, vinyl acetate resin, vinyl alcohol resin and polyamide. , Uniaxially or biaxially stretched or unstretched film, and film which has or has not been subjected to surface treatment such as corona discharge treatment or low temperature plasma treatment. The drying temperature is usually about 40-60 ° C. On the printing surface of the film printed with the laminate ink composition of the present invention, another film or an aluminum foil is attached with or without a urethane-based or modified polyolefin-based adhesive, or an anchor coating agent is applied. Extrusion is laminated 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 applications that require retort sterilization, use polyester film /
A laminated film composed of polypropylene film, polyamide film / polypropylene film, polyester film / aluminum foil / polypropylene film, etc. is suitable, and in the case of boiling sterilization, laminated film composed of polyester film / polyethylene film, polyamide film / polyethylene film, etc. Is suitable. Anchor coat agents include organotitanium-based, polyisocyanate-based, polyethyleneimine-based, polybutadiene-based, etc., and resin to be extrusion laminated is low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene. , Ethylene-vinyl acetate copolymers or saponified products thereof, ethylene-ethyl acrylate copolymers,
Examples include ethylene-acrylic acid copolymer, polyethylene terephthalate, polyamide, polymethylpentene-1, and ionomer. Extrusion laminate is 120 to 3
It is carried out by applying an extrusion coating to the printed surface of the film by heating the resin melted by heating to 10 ° C. and immediately cooling it with a cooling means such as a cooling roll.

The laminated film thus obtained is formed into a container shape such as a bag shape, filled with foods and drinks, pharmaceuticals, medical instruments and the like, and heat-sterilized. The conditions for heat sterilization are usually
Low temperature boiling sterilization is 85 ℃ for 30 minutes, high temperature boiling sterilization is 100 ℃ for 30 minutes, retort sterilization is 120 to 130 ℃ for 30 minutes, and high retort sterilization is 140 to 145 ℃ for 10 minutes.

(Examples) Hereinafter, the present invention will be described with reference to Examples. In the examples, “part” means “part by weight” and “%” means “% by weight”.

Synthesis Example 1 228 parts of polyester diol having an average molecular weight of 2000 obtained by reacting adipic acid and 1,4-butanediol, 51 parts of isophorone diisocyanate and 19 methyl ethyl ketone
4 parts were reacted at 75 ° C. for 6 hours to obtain 473 parts of a solvent solution of a terminal isocyanate prepolymer.

Isophorone diamine 18 parts, di-n-butylamine 3.0
Parts, 286 parts of methyl ethyl ketone and 220 parts of isopropyl alcohol were mixed, and 473 parts of the obtained solvent solution of the terminal isocyanate prepolymer was gradually added at room temperature and then reacted at 50 ° C for 1 hour to give a solid content of 30%. Thus, a linear polyurethane resin solution A having a viscosity of 6P at 25 ° C. was obtained.

Synthesis Examples 2 to 4 Linear polyurethane resin solutions B to D were obtained in the same manner as in Synthesis Example 1 using the raw materials shown in Table 1.

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 Triisocyanate adduct obtained by reacting 1 mol of trimethylolpropane with 3 mol of hexamethylene diisocyanate Body blocked with diethyl malonate 2.3 parts After kneading the mixture with the above composition for 20 hours in a ball mill, add a mixed solvent consisting of 30% methyl ethyl ketone, 40% toluene and 30% isopropyl alcohol, and at Zern Cup No. 25 at 25 ° C. The viscosity measured in 3 was adjusted to 18 seconds. Using a gravure plate with a plate depth of 35 μm, the resulting laminated ink was coated with a corona discharge treated nylon film “Emblem” with a thickness of 15 μm (manufactured by Unitika Ltd.,
The product was printed on the corona discharge treated surface of the product name) and dried.

Methyl ethyl ketone was added to the residual ink of the laminated ink after printing.
30%, toluene 40% and isopropyl alcohol 30%
Add a mixed solvent consisting of
After readjusting the viscosity measured in 3 to 18 seconds, 40 ℃
Table 2 shows the results of evaluation of the rate of change in viscosity and the fading stability of the viscosity re-adjusted product of the residual thickness of the laminated ink before and after storage for 1 week. The rate of change in viscosity of the reconstituted viscosity of the residual ink of the laminated ink before and after storage was calculated using the following formula; The calculation result is ○: less than 0.5, ×: 1.0
Displayed above. For the evaluation of the fading stability of the viscosity re-adjusted product of the laminated ink residue before and after storage, the viscosity re-adjusted product of the laminated ink residue before storage was bar-coated on a film.
After applying and drying No.6 as a standard sample, the viscosity of the laminated ink residual after storage was re-adjusted so that the viscosity measured by Zahn cup No.3 was 18 seconds. A sample was prepared in the same manner as the standard sample, and the difference between the color of the standard sample and the color of the sample was visually observed. The evaluation results are indicated by ○: no color difference, Δ: slightly discolored, but no problem in practical use, ×: markedly discolored.

On the other hand, the two printing films obtained were overlaid, 500 g / cm
^After applying a load of ² and leaving it at 40 ° C for 24 hours, the peeling resistance when the printing film was peeled off and the presence or absence of peeling of the laminated ink were evaluated as blocking resistance. The evaluation results are shown in Table 2. The evaluation results are as follows: ○: peeling was possible without resistance, and there was no peeling of the laminating ink. △: There was some resistance during peeling, but there was no peeling of the laminating ink, and there was no practical problem. ×: During peeling It was displayed because the resistance was high and the peeling of the laminating ink occurred.

Also, apply the two-component polyurethane adhesives "Adcoat AD900" and "Adcoat RT-5" (both manufactured by Toyo Morton Co., Ltd., trade name) on the obtained printed surface, dry, and apply the thickness to the applied surface. 60 μm medium density polyethylene film “NB-
1 "(trade name, manufactured by Tama Poly Co., Ltd.) was pasted and aged at 40 ° C for 2 days to obtain a laminated film. The two laminated films obtained were stacked so that the surfaces of the medium-density polyethylene films overlap, and the periphery was heat-sealed to form a bag, and salad oil / vinegar / water = 1/1/1
The mixture was mixed (weight ratio), and the appearance change after boil sterilization treatment at 100 ° C for 30 minutes and the appearance change after retort sterilization treatment at 120 ° C for 30 minutes were visually evaluated.
The evaluation results are shown in Table 2. The evaluation results are shown by ○: no change, ×: blister occurred on the entire surface, or delaminated on the entire surface.

Examples 2 to 4 Instead of the linear polyurethane resin solution A, the linear polyurethane resin solution B was used in Example 2, the linear polyurethane resin solution C was used in Example 3, and the linear polyurethane resin solution was used in Example 4. A laminated ink was obtained and evaluated in the same manner as in Example 1 except that the solution D was used.

Example 5 Blocked isocyanate compound used in Example 2
A laminate was prepared in the same manner as in Example 2 except that 2.4 parts of the blocked isocyanate compound obtained by blocking the triisocyanate adduct used as the raw material of the blocked isocyanate compound in Example 1 with methyl ethyl ketone oxy was used in place of 2.3 parts. Table 2 shows the results of the ink obtained and evaluated.

Examples 6 to 10 Blocked isocyanate compound used in Example 2
Instead of 2.3 parts, a blocked isocyanate compound in which a triisocyanate adduct obtained by reacting 3 mol of isophorone diisocyanate with 1 mol of trimethylolpropane was blocked with methyl ethyl ketone oxime was used. 0.07 parts in Example 7, 0.6 parts in Example 8, 3.0 parts in Example 9, 6.0 parts in Example 10, respectively, and 0.5 part of dibutyltin dilaurate was added to 100 parts of the blocked isocyanate compound. Laminated inks were obtained and evaluated in the same manner as in Example 2 except for the above, and the results are shown in Table 2.

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

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 in place of the blocked isocyanate compound.
Table 2 shows the evaluation results obtained by obtaining a laminated ink in the same manner as in.

Comparative Example 3 Blocked isocyanate compound used in Example 2
Example 2 except that 2.4 parts of the blocked isocyanate compound obtained by blocking the triisocyanate adduct used as the raw material of the blocked isocyanate compound in Example 1 with caprolactam was used in place of 2.3 parts
Table 2 shows the evaluation results obtained by obtaining a laminated ink in the same manner as in.

Comparative Example 4 Blocked isocyanate compound used in Example 2
A laminated ink was prepared in the same manner as in Example 2 except that 3.0 parts of the blocked isocyanate compound obtained by blocking the triisocyanate adduct used as the raw material of the blocked isocyanate compound in Example 1 with phenol was used in place of 2.3 parts. Obtained and evaluated results are shown in Table 2.
Shown in.

[Advantages of the Invention] According to the present invention, storage stability and residual meat stability are good,
A laminated ink composition for heat sterilization treatment, which does not cause blocking even when the printed film before laminating is wound up and stored, and does not cause delamination or blistering between laminate films during heat sterilization Has come to be obtained.

Claims (1)

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