JP2506404B2 - LAMINATE PRINTING INK COMPOSITION, LAMINATE PROCESSING METHOD USING THE SAME, AND LAMINATE PROCESSED PRODUCT - Google Patents

Description

TECHNICAL FIELD The present invention relates to a printing ink composition for laminating a plastic film or sheet, a laminating method using the same, and a laminating product.

[Prior Art] With the diversification of packaging containers and the higher functionality of synthetic resin products, printing inks used for decoration of plastic films or for surface protection have been required to have high performance and quality. Is starting to appear.

In particular, regarding printing inks used for packaging containers, a wide range of adhesiveness to various composite films for cosmetics and high quality packaging containers, as well as various post-processing suitability such as various laminating suitability, boil suitability, retort suitability. It is becoming necessary to deal with such issues.

Generally, methods such as gravure printing and flexographic printing are used for printing plastic films, but in the case of film printing as a packaging material, most of them are winding methods, so printing ink requires fast drying. To be done. When used as food packaging, it is required that the residual solvent content be low.

In addition, in order to improve the performance of packaging materials, dry lamination and extrusion lamination are often performed after printing. In particular, polyester (PET) and nylon (NY) films are laminated with polyethylene, polypropylene, etc., taking advantage of their strength and airtightness superior to other films. In this case, urethane is used for dry lamination. An adhesive such as the above is used, and an anchor coating agent is used in the case of extrusion lamination processing. Further, an aluminum foil may be interposed in the middle so that the packaging material can be boiled or retort processed. Although the strength up to retort processing is not required, in the field of packaging materials based on transparent base materials, a laminate in which stretched polypropylene (OPP) is used as the base material film and directly coated with molten polypropylene without using an anchor coating agent. The processing method (usually called PP direct laminating) is also used.

In order to perform the post-processing as described above, it is required that the printing ink used at all stages has not only the adhesiveness to various substrate films and printability, but also the suitability for each post-processing. In addition, such various suitability is mainly determined by the binder resin used in the printing ink or the like.

Conventionally, as a printing ink used for a polyester film, one using a thermoplastic polyester resin as a binder has been used, and for a nylon film and a polyester film, a two-component type reactive ink of a polyester resin having a hydroxyl group and an isocyanate compound. Is used. Further, recently, printing inks having a polyurethane resin as a binder have been widely used as those having wide suitability for base films such as nylon, polyester and the like.

On the other hand, printing inks using a chlorinated polyolefin with a relatively low degree of chlorination, such as chlorinated polypropylene, as a binder are used for polyolefins that are subjected to PP direct lamination.

[Problems to be Solved by the Invention] However, in the case of using a thermoplastic polyester resin as a binder, not only the substrate film is limited, but also the drying property is not sufficient and there is a problem in workability such as occurrence of blocking, Since the two-component ink is a reactive type, it has a short pot life, various restrictions are imposed on workability, and there is an economic loss such as discarding unused ink. In addition, printing inks using polyurethane resin as a binder show sufficient adhesiveness to nylon films, polyester films, etc., but still sufficient adhesiveness to general-purpose films such as polyethylene films and polypropylene films. In addition, there is a problem that the suitability for laminating, especially the suitability for PP direct laminating is insufficient.

On the other hand, printing inks using chlorinated polyolefin as a binder show good adhesiveness to polyolefin films in the low chlorination range, but at high chlorination degrees they do not adhere to polyolefin films. It is inferior. In addition, since it does not have sufficient adhesiveness to nylon films and polyester films, the base film is greatly limited, and although it is suitable for PP direct lamination, it is not suitable for boil and retort, and its use is limited.

Further, since a large amount of toluene has to be used as a solvent in this ink, the residual solvent poses a serious problem in food packaging applications.

As described above, in the conventional printing ink, the described film is limited, or the adhesiveness is insufficient even if it has general versatility with respect to the base film, and the problem of residual solvent in the food field, various It was not suitable for laminating, boiling, or retorting.

Therefore, in reality, printing inks containing binders suitable for each base film, various laminating processes or retort processes were manufactured each time. However, there is a big problem in the printing process or inventory control of materials and inks for these processes.

Therefore, it is an object of the present invention to provide a printing ink composition for laminating, which has a wide range of adhesiveness to various substrate films, various laminating suitability, and further boil and retort suitability.

In addition, the present invention significantly reduces residual solvent, which was a major problem of conventional PP direct laminating ink.
An object is to provide a printing ink composition for processing for direct lamination.

Still another object of the present invention is to provide a laminating method and a laminated product using the above printing ink for laminating.

[Means for Solving the Problems] That is, the present invention is a printing ink composition for laminating, which comprises a pigment, a resin and an organic solvent as essential components, wherein the resin is a polyurethane resin having a molecular weight in the range of 5,000 to 200,000. 50-90 parts by weight, and molecular weight 5,000
~ 300,000, chlorinated degree 35 ~ 60 chlorinated polypropylene 10
A printing ink composition for laminating, characterized in that it contains a mixture with 50 to 50 parts by weight as a main component and further has a toluene content of 70% by weight or less based on the total amount of organic solvent components in the ink ( Claim 1.).

Still further, the present invention relates to a laminating method using the printing ink composition for laminating, and a laminated product.

 Each of the present inventions will be described below.

The polyurethane resin used in the present invention has a molecular weight of 5,
000 to 200,000 can be used, 10,000 to 150,
000 is preferable. If the molecular weight is less than 5,000, blocking tends to occur and the suitability for lamination tends to be insufficient. On the other hand, when it exceeds 200,000, the pigment dispersibility tends to decrease.

In order to obtain the polyurethane resin, a high molecular weight diol compound (molecular weight of 400 to 4,000) such as a polyether type and / or polyester type diol, an organic diisocyanate compound, a chain extender, a reaction terminator, etc., if necessary, various conventionally known compounds. It can be manufactured using additives.

Typical polyether type diols include polyoxyalkylene glycols such as polyethylene glycol, polypropylene glycol and polyoxytetramethylene glycol, and alkylene oxide adducts of bisphenol A such as ethylene oxide, propylene oxide and ethylene propylene oxide. It is illustrated.

Representative polyester type diols include dibasic acids such as adipic acid, phthalic anhydride, isophthalic acid, maleic acid, fumaric acid and succinic acid, and ethylene glycol, diethylene glycol, propylene glycol, 1,4 butanediol, neo Pentyl glycol, 1,6
Examples thereof include those obtained by condensation reaction with glycols such as hexanediol.

Alternatively, polycaprolactone diol, polycarbonate diol, polybutanediene diol and the like can be mentioned as the diol component.

A typical organic diisocyanate component is
Tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, methylene diisocyanate, isopropylene diisocyanate, hexamethylene diisocyanate, 2,2,4- or 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, hydrogenated xylylene diisocyanate, 1,4
-Cyclohexane diisocyanate, isophorone diisocyanate and the like can be mentioned.

Alicyclic diisocyanates such as isophorone diisocyanate and 4,4-dichlorohexylmethane diisocyanate are preferable from the viewpoint that a resin having excellent solubility can be obtained.

Typical diamines as chain extenders and the like include ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclophoronehexylmethanediamine and the like, and typical diols include ethylene glycol. , Propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,4-cyclohexyl glycol and the like.

As typical examples of the reaction terminator, monoamines such as n-butylamine and monoethanolamine, and monoalcohols such as methanol, ethanol and propylene alcohol can be used.

As the polyurethane resin used in the present invention,
The above diol component, diisocyanate component and a chain extender used as necessary, a reaction terminator or by adjusting the reaction ratio, or by using a special chain extender, a reaction terminator, a free hydroxyl group, an amino group, A polyurethane resin having an imino group, an amino alcoholic hydroxyl group or the like introduced therein can be synthesized.

The solvent used in the above reaction is usually
Aromatic solvents such as benzene, toluene and xylene which are often used as solvents for printing inks, ester solvents such as ethyl acetate, propyl acetate and butyl acetate, alcohol solvents such as methanol, ethanol, isopropanol and n-butanol, Examples include ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, which may be used alone or as a mixed solvent.Residual solvents, ester solvents from the viewpoint of the working environment, alcohol solvents, or a mixed solvent containing these solvents as the main components. Is the best.

On the other hand, the chlorinated polypropylene to be mixed with the polyurethane resin may have a molecular weight of 5,000 to 300,000. If the molecular weight is less than 5,000, blocking tends to occur and the suitability for lamination tends to be insufficient. Also, if the molecular weight exceeds 300,000, solubility becomes a problem.

Further, if the chlorination degree of the chlorinated polypropylene is less than 35, the solubility of the toluene content in the organic solvent of 70% by weight or less decreases, and if it exceeds 60, the adhesion to the polyolefin film decreases, Chlorinated polypropylene having a chlorination degree of 35 to 60 can be used. In particular, in consideration of reduction of residual solvent, when using a mixed solvent containing as little toluene as possible, it is preferable to use chlorinated polypropylene having a degree of chlorination of 37 or more from the viewpoint of compatibility with urethane.

Further, a modified product of chlorinated polypropylene can also be used. For example, a polymerizable acrylic compound (acrylic acid, methacrylic acid or an alkyl ester thereof) or an unsaturated polycarboxylic acid (maleic acid, maleic anhydride, etc.) can be used for these chlorinated polypropylenes. (Itaconic acid, itaconic anhydride, etc.), for example, JP-A-57-281
23, or chlorinated polyolefins obtained by graft-polymerizing the above unsaturated polycarboxylic acids, such as those described in JP-A No. 50-36128.

And, in order to obtain a printing ink with adhesiveness to a wide range of films and other laminating suitability while maintaining the PP direct laminating suitability, chlorinated polypropylene and polyurethane resin in a weight ratio of 10/90
It is necessary to mix and use in the range of 50/50 to 50/50, more preferably 10/90 to 30/70. When the content of chlorinated polypropylene is less than 10%, the adhesion to polyolefin is lowered, and when it exceeds 50%, residual solvent becomes a problem. In printing in the field of food packaging, even if residual solvent is a particular problem, use a mixed solvent that uses as little toluene as possible by using a chlorinated polypropylene with a chlorination degree of 35 or more, preferably 37 or more. This makes it possible to significantly reduce the problem of residual solvent.

In the case of producing a printing ink for laminating using the mixture of the polyurethane resin and the chlorinated polypropylene obtained as described above, various pigments and the solvent are added to the mixture, and the mixture is kneaded and dispersed, Additives such as antiblocking agents, plasticizers, etc., if necessary, or compatible nitrification cotton, chlorinated polyethylene, chlorinated ethylene /
Resins such as propylene or chlorosulfonated polyolefin, ethylene / vinyl acetate copolymer or its chlorinated or chlorosulfonated product, maleic acid resin or vinyl chloride / vinyl acetate copolymer can be used in combination for production.

[Examples] Hereinafter, specific examples will be described, but the present invention is not limited thereto. (The parts in the examples and the like indicate parts by weight.) Polyurethane resin synthesis example 1 40.0 parts of isophorone diisocyanate and 1,4 adipic acid were added to a four-necked flask equipped with a stirrer, Dimroth, and a nitrogen gas introduction tube. Molecular weight synthesized from butanediol
Charge 200 parts of 2,000 polyester diols and react for several hours while introducing nitrogen gas. After cooling, toluene 31
After adding 6 parts, 316 parts of methyl ethyl ketone and 158 parts of IPA, 95.4 parts of isophoronediamine was added to perform chain extension,
Further, 2.9 parts of monoethanolamine was added to stop the reaction to obtain a polyurethane resin solution (1).

Polyurethane Resin Synthesis Example 2 Using the same equipment as in Synthesis Example 1, 200 parts of polycaprolactone diol having a molecular weight of 1,000, 57.7 parts of isophorone diisocyanate, 5.1 parts of isophorone diamine, 3.7 parts of monoethanolamine, 248 parts of methyl ethyl ketone.
248 parts and IPA 123 parts were charged and reacted in the same manner as in Synthesis Example 1 to obtain a polyurethane resin solution (2).

Polyurethane Resin Synthesis Example 3 Using the same equipment as in Synthesis Example 1, 200 parts of polyester diol having an average molecular weight of 2,000 obtained from adipic acid and 1,4 butanediol, and isophorone diisocyanate 44.
Charge 4 parts and react for several hours while introducing nitrogen gas. After cooling, toluene 242 parts, methyl ethyl ketone 242
Parts, 121 parts isopropyl alcohol. Dissolve uniformly, add 12.3 parts of methyliminobispropylamine,
Furthermore, the reaction was stopped by adding 3.1 parts of dimethylaminopropylamine to obtain a polyurethane resin solution (3).

Example 1 Urethane the resin synthesis example 1 obtained in the polyurethane resin solution (1) 70 parts by weight, chlorinated polypropylene resin was mixed with 30% toluene solution 30 parts of (chlorination degree 38) solution
(A) For a binder composed of 30 parts and 25 parts of toluene,
Titanium oxide (30 parts) and ethyl acetate (15 parts) are added to the white ink, and cyanine blue pigment (10 parts) and ethyl acetate (35 parts) are added to the blue ink, and the mixture is kneaded by a conventional method to produce a printing ink for lamination.

Examples 2 to 4, Comparative Example 1 A white ink and a blue ink are produced by mixing in the same manner as in Example 1, except that 30 parts of each of the resin solutions B to D having the following composition are used.

Resin solution B (Example 2) Polyurethane resin solution (2) 70 parts 30% toluene solution of chlorinated polypropylene (chlorination degree 38) 30 parts Resin solution C (Example 3) Polyurethane resin solution (3) 70 parts Chlorination 30% toluene solution of polypropylene (chlorination degree 38) 30 parts Resin solution D (Example 4) Polyurethane resin solution (1) 60 parts 30% toluene solution of chlorinated polypropylene (degree of chlorination 38) 40 parts Resin solution E ( Comparative Example 1) Polyurethane resin solution (1) 100 parts Comparative Example 2 A printing ink made of the following materials is manufactured as an ink imparted with the conventional PP luder suitability.

Evaluation Test 1 With respect to each of the printing inks obtained in Examples 1 to 4 and Comparative Examples 1 and 2, the adhesiveness to various films, pigment dispersibility, laminating suitability, boil suitability, and retort suitability were evaluated, and the results are shown in Table- Shown in 1.

As can be seen from the results in Table-1, the printing ink for lamination using the mixed resin of the polyurethane resin and the chlorinated polypropylene as the binder had poor adhesion to the polyolefin of the conventional ink using the polyurethane resin as the binder (Comparative Example 1). In addition, it is possible to simultaneously improve the sufficient point of the suitability for PP ruder and the insufficient point of the adhesiveness to the polyester and nylon film and the boiling point and the retort suitability in the conventional ink for PP ruder (Comparative Example 3) described later. Recognize.

In Comparative Example 2, it is understood that the adhesiveness to nylon and polyester and the suitability for foil and retort are not sufficient.

 The evaluation methods are as follows.

1) Adhesiveness Each test ink was used to print on a specified film with a gravure proofing machine, allowed to stand for 1 day, and then a cellophane tape was attached to the printing surface. When this was rapidly peeled off, the printed film did not come off at all. The ones with 80% or more remaining in the film are indicated by O, those remaining with 50 to 80% by Δ, and those remaining less than 20% by X.

2) Pigment dispersibility Regarding the color development, transparency and density of the printed matter, the best one was evaluated as ⊚, the one that does not interfere with printing was evaluated as ◯, the one that was not sufficient was evaluated as Δ, and the unsuitable one was evaluated as x.

3) Extrusion laminating strength For each printed material, an imine type is used for oriented polypropylene (OPP), polyethylene terephthalate (PET), and an isocyanate type anchor coating agent is used for nylon (NY), and molten polyethylene is laminated by an extrusion laminating machine. After 3 days, the sample was cut into a width of 15 mm, and the T-type peel strength was measured with a peel tester manufactured by Yasuda Seiki.

4) Dry Lamination Strength A urethane adhesive was used for each printed matter, a CCP (unstretched polypropylene) film was laminated by a dry laminating machine, and after 3 days, peel strength was measured by the same method as the extrusion lamination strength measurement.

5) Boil suitability and retort suitability After laminating, the printed matter is made into a bag, and the mixture of water / oil is put inside and sealed.
For the retort suitability for 120 minutes, after heating at 120 ° C / 30 minutes, the presence or absence of lami floating was judged from the appearance. The case where no laminating float was observed was evaluated as ◯, the case where the laminating float was recognized as pinhole was evaluated as Δ, and the case where the entire delamination occurred was evaluated as x.

6) PP direct laminating suitability (PP ruder strength) OPP printed matter is extruded by a laminating machine.
The molten polypropylene was directly laminated, and after 2 days, the peel strength was measured by the same method as the measurement of the extrusion laminate strength.

Comparative Examples 3 and 4 and Example 5 Comparison of performance due to difference in chlorination degree of chlorinated polypropylene mixed with polyurethane resin, particularly adhesiveness to polyolefin film and residual solvent which is a problem when used for food packaging Therefore, using the following materials, white ink and blue ink are manufactured in the same manner as in Example 1.

In addition, the solvent composition weight ratio (toluene / methyl ethyl ketone / isopropylene alcohol) in the ink system necessary for obtaining sufficient storage stability in ink formulation is shown.

Comparative Example 3 (70/25/5) Comparative Example 4 (70/25/5) Example 5 (40/40/20) Evaluation Test 2 While using the respective inks of Comparative Examples 3 and 4 and Example 5 in the same manner as in Evaluation Test 1, the residual solvent of the obtained printed matter was measured and added to Table 1 above. The residual solvent was also measured for Comparative Examples 1 and 2, and
Append to 1.

From the above results, the use of chlorinated polypropylene having a high degree of chlorination makes it possible to reduce the amount of toluene, which is an aromatic solvent, and is suitable for food packaging. It is also understood that the restriction of the residual solvent is lessened when the one having a high degree of chlorination is used.

 The residual solvent was measured by the following method.

Residual solvent: Put each printed material (0.2 m ² ) in a 500 cc flask, heat in an oven at 130 ° C for 10 minutes to evaporate the solvent remaining in the printed material, collect 1 cc of gas from the flask, and remove the gas. The residual solvent (PPM) is measured by chromatography.

Due to the boiling point of the solvent used, the residual solvent is mainly toluene (boiling point: 110.7 ° C), and approximately 10 ppm or less can be expected.

[Effects of the Invention] As described above in the Examples, the printing ink for lamination obtained in the present invention has, in particular, 1) adhesiveness to a wide range of plastic films such as polyolefin film, polyester film, nylon film,
It has excellent properties such as 2) pigment dispersibility, 3) storage stability, 4) suitability for lamination, especially suitability for PP direct lamination, and 5) suitability for post-processing such as boiling and retort.

Further, by considering the mixing ratio of the polyurethane resin mixed and used in the present invention and chlorinated polypropylene or the chlorination degree of chlorinated polypropylene, the adhesiveness to various plastics, boil, retort suitability, suitability for residual solvent, etc. It can be adjusted, and it also has the effect that the most suitable composition can be adjusted according to the use and purpose of the printed matter.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshinori Kano 2-6-2 Higashi Tenma, Kita-ku, Osaka City, Osaka Prefecture Minamimorimachi Central Building Sakata Inx Co., Ltd. (72) Inventor Takahiko Inoue Kita, Osaka City, Osaka Prefecture 2-6-2 Higashi-Tenma-ku, Minamimori-cho Central Building Sakata Inx Co., Ltd. (56) References JP-A-61-255937 (JP, A)

Claims (5)

(57) [Claims] 1. A printing ink composition for laminating, comprising a pigment, a resin and an organic solvent as essential components, wherein the resin is 50 to 90 parts by weight of a polyurethane resin having a molecular weight of 5,000 to 200,000, and a molecular weight of 5,000 to. Contains as a main component a mixture of 300,000 and 10-50 parts by weight of chlorinated polypropylene with a degree of chlorination of 35-60, and the content of toluene is 70% by weight or less based on the total amount of organic solvent components in the ink. A printing ink composition for laminating, characterized in that 2. A plastic film or sheet is printed with the printing ink composition for laminating according to claim 1 by a gravure or flexographic printing method, and then a molten plastic or a plastic film is laminated. Laminating method. 3. A polyolefin film or sheet is printed by a gravure or flexographic printing method using the printing ink composition for laminating according to claim 1, and then a molten polyolefin film is coated with an anchor coating agent. Laminating method to laminate without using. 4. A laminated product obtained by the laminating method according to claim 2. 5. A food packaging container obtained by the laminating method according to claim 2.