JP2006282947A - Coating composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating composition which, while maintaining the quality of the present situation, has a low content of a remaining solvent after coating and is excellent in gas barrier properties. <P>SOLUTION: The coating composition contains a resin and a solvent. The solvent contains an alcohol component at least containing tertiary butyl alcohol in an amount of 1-50 mass% of the total solvent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a coating composition. More specifically, the present invention relates to a coating composition having a small amount of residual solvent in a coating layer after coating.

In the field of food packaging, an ink composition is printed on a printing substrate film called a base film to form a printed layer, and then a sealing material called a heat-sealable sealant film is laminated to form a packaging material. Many packaging bags having a laminated structure in which a part is melt-pressed to form a bag are used. In such a packaging bag, since the printing layer is sealed between the base film and the sealant film, the solvent contained in the ink or the like tends to remain in the printing layer. When the components eluted from the remaining solvent and pigment permeate the sealant layer and move into the bag, an unpleasant odor is given at the time of opening, and it also causes abnormal quality of food such as a bad odor.

For such problems, conventionally, the resin composition should be examined so that the solvent does not remain in the coating layer such as the printing layer, or the structure of the packaging material should be examined so that the solvent may not be transferred as much as possible. (See, for example, Patent Documents 1, 2, 3, and 4).

For example, in a packaging bag having a laminate structure, an inorganic layered compound or the like is added to a resin having a gas barrier property, and a gas barrier layer that suppresses the permeation of gas by a maze effect is provided to prevent migration of residual solvent in the printing ink layer. Attempts have also been made. However, in a packaging bag including a gas barrier layer, if there is a residual solvent in the printing ink layer, it will remain in the packaging bag without permeating it, which may affect the resistance of the packaging bag. It is required to use an ink composition having a small amount. Furthermore, the solvent contained in the gas barrier layer itself may permeate the sealing material layer, and it is a problem to reduce the residual solvent amount for the gas barrier coating agent that forms the gas barrier layer.

On the other hand, improvements have also been attempted from the viewpoint of solvent safety. In recent years, due to the growing interest in environmental problems, the replacement of organic solvent systems that have been used in the past with alcohol-based solvents has become more environmentally friendly. Is underway, and new systems are being studied.

Originally, in selecting a solvent to be used for a coating composition such as an ink composition or a gas barrier coating agent, whether or not a resin to be used can be dissolved is first examined. In addition, since a solvent with higher volatility is less likely to remain, conventionally, an alcohol having a relatively small number of carbon atoms is used to reduce the amount of residual solvent even when an alcohol-based solvent is used. ing. However, the demand for reducing the amount of residual solvent in the market is becoming stricter, and it is possible to further reduce the amount of residual solvent while maintaining the current quality such as printability and post-processability. It has been demanded.

JP 2004-175867 A JP-A-5-222330 JP 2003-276124 A JP 2004-322601 A

This invention is made | formed in view of the said problem, and it aims at providing the coating composition with little residual solvent amount. More specifically, an object is to provide a coating composition having a small amount of residual solvent in the coating layer after coating.

The present inventors are a coating composition obtained by dissolving a resin in a solvent containing an alcohol component, and the solvent contains tertiary butyl alcohol in an amount of 1 to 50% by mass based on the total amount of the solvent. By using the coating composition, the present inventors have found that the amount of residual solvent in the coating layer can be greatly reduced without impairing the quality and properties after coating of the coating composition, and the present invention has been completed.

That is, the present invention provides (1) a coating composition containing a resin and a solvent, wherein the solvent contains an alcohol component containing at least tertiary butyl alcohol, and the tertiary butyl alcohol is added to the total amount of solvents in the solvent. It is related with the coating composition characterized by containing 1-50 mass%.

The present invention also relates to (2) the coating composition as described in (1) above, wherein the resin is a high hydrogen bond resin.

The present invention also provides (3) the coating composition as described in (2) above, wherein the high hydrogen bonding resin is a polyvinyl alcohol polymer resin or an ethylene-vinyl alcohol copolymer resin. About.

In the present invention, (4) the resin is a polyvinyl alcohol polymer resin or an ethylene-vinyl alcohol copolymer resin,
(1) to (1) above, wherein the solvent contains an alcohol component containing at least tertiary butyl alcohol and water, and the content ratio (mass ratio) of the alcohol component / water is 30/70 to 70/30. The coating composition according to any one of (3).

Moreover, this invention relates to the coating composition in any one of said (1)-(3) item containing (5) inorganic layered compound.

Moreover, this invention relates to the coating composition in any one of the said (1)-(5) term which contains 3-40 mass% of (6) tertiary butyl alcohol with respect to the total amount of solvents.

Moreover, this invention relates to the coating composition in any one of said (1)-(6) item which contains 5-30 mass% of (7) tertiary butyl alcohol with respect to the total amount of solvents.

Moreover, this invention is 5-30 mass% with respect to the total amount of solvents, and (8) tertiary butyl alcohol, and any one of said (1)-(7) term containing C1-C3 alcohol. It relates to the coating composition as described above.

The present invention also relates to (9) the coating composition according to any one of (1) to (8) above, further containing a colorant.

Hereinafter, the present invention will be described in detail.
The coating composition according to the present invention is a coating composition containing a resin and a solvent, wherein the solvent contains an alcohol containing at least tertiary butyl alcohol, and the tertiary butyl alcohol is included in the solvent with respect to the total amount of the solvent. It is a coating composition characterized by containing 1-50 mass%. The coating composition includes a printing ink composition including a surface printing or a laminate for printing on a printing substrate film, a gas barrier coating agent, various coating coating agents, and the like. Especially the coating composition of this invention can be used conveniently as a coating composition for food packaging materials, or a coating composition for pharmaceutical packaging materials.

Here, first, what kind of concept the solvent has been selected in the conventional coating composition, and what effect the tertiary butyl alcohol has on the problems that cannot be solved under that concept Explain how.

Materials that cover the surface of an adherend including an ink composition and a gas barrier coating agent are generally referred to as a coating composition. Then, a liquid coating composition in which a solid material such as a resin or pigment is dissolved or dispersed in a solvent is coated and printed on an adherend by a coating machine or a printing machine, and then dried. A solid film is formed on the surface of the adherend.

In order to form a coating having a thickness as set using such a liquid coating composition, it is essential to maintain an optimum viscosity during coating and printing. The viscosity of the coating composition varies depending on various factors such as evaporation of the solvent, environmental temperature and mechanical stress applied to the coating agent, but the degree of the change usually increases as the solid content increases. Recently, the concentration of solid components (solid content) such as resins and pigments in the coating composition is increased as much as possible, and the tendency to lower the viscosity is increased while maintaining the optimum viscosity. It has become difficult.

Since tertiary butyl alcohol has a melting point of 25.5 ° C., it is almost solid in the coating / printing work environment, and it is difficult to adjust the viscosity to use a solid one as a solvent. This is contrary to the purpose of maintaining the above optimum viscosity. Further, in the production of the coating composition, if it is a liquid solvent, it can be added to the production tank as it is through the piping from the storage tank, but in the case of a solid material, such a method cannot be used, and the aspect of production efficiency. But it is disadvantageous.

As described above, the use of tertiary butyl alcohol as a solvent is disadvantageous in terms of viscosity maintenance and production efficiency. In fact, there have been examples in the past that have been used in coating composition applications. It is no exaggeration to say that there is no.

In contrast, the present inventor solves the problem that the residual amount of the solvent after drying increases when a resin soluble in a solvent containing alcohol, particularly a high hydrogen bonding resin, is used for the coating composition. For this reason, as a result of various studies, the effectiveness of using tertiary butyl alcohol for the first time was derived.

Recently, there is a growing demand for the use of environmentally friendly alcohol solvents, and it is necessary to reduce the amount of residual solvent after drying as much as possible. However, considering the original performance required of the solvent, It is important to select a well-balanced solvent that has sufficient ability to dissolve the resin and can maintain the viscosity and drying property of the coating composition obtained by using the solvent at an appropriate level.

For example, in order to reduce the drying rate of the coating composition and the amount of residual solvent, it is usually advantageous to select an alcohol having a lower carbon number, assuming that a fast evaporation rate would be effective. It is guessed. Actually, lower alcohols having 1 to 3 carbon atoms such as methanol, ethanol, isopropyl alcohol and the like have generally been used as alcohol solvents in accordance with the above-mentioned concept. However, particularly in a system using a high hydrogen bond resin, when the coating composition film is formed, the amount of the lower alcohol retained and retained in the system increases, which is not compatible with the above assumption. A phenomenon was observed.

Regarding the above phenomenon, the present inventors have described that since the lower alcohols having 1 to 3 carbon atoms are all primary and secondary alcohols, they have high affinity with the resin and are good in terms of solubility. Therefore, it was speculated that high energy would be required to remove the solvent without leaving it in the film. Based on this assumption, in order to balance the maintenance of dryness and solubility and the reduction of the residual amount, an alcohol solvent was examined.

And as a result of focusing on the following [1] to [3] as technical concepts, by using tertiary butyl alcohol, the ability to dissolve the resin, and the viscosity and drying properties as a coating composition The inventors have found that the amount of residual solvent can be further reduced while maintaining an appropriate level, and have completed the present invention.
[1] Alcohols with a small number of carbons can evaporate too quickly and cause a sudden viscosity change of the coating composition. On the other hand, alcohol having a large number of carbon atoms requires relatively high evaporation energy. Considering these, the main component is alcohol having an evaporation rate comparable to that of ethanol to isopropyl alcohol.
[2] In particular, since a high hydrogen bonding resin causes a decrease in solubility due to crystallization, an alcohol that can inhibit crystallization with a smaller amount is used.
[3] Proactively consider bulky tertiary alcohols.

The following can be considered as the reason why tertiary butyl alcohol exhibits such an effect. Tertiary butyl alcohol has almost the same boiling point as isopropyl alcohol (IPA), which has one less carbon number, and has a feature that the amount of heat required for evaporation is less than that of IPA. It is advantageous (technology having the same function as [1] above). In terms of molecular structure, the alcoholic hydroxyl group prevents the occurrence of hydrogen bonding within the resin of the high hydrogen bonding resin or between the resins, and suppresses the decrease in solubility due to crystallization (see [2 above]. The bulky tertiary butyl group moderately weakens the hydrogen bonding force due to steric hindrance, and can be detached from the system with less kinetic (thermal) energy (technique [3] above).

Furthermore, the use of tertiary butyl alcohol has significant advantages. It is possible to mix tertiary butyl alcohol with water in any ratio, and in the future as a solvent that does not burden the environment, there is no problem in the ratio of use with water even when it is shifted to the water-alcohol system. It does not occur.

Thus, tertiary butyl alcohol has a very high effect, and when 1 to 50% of tertiary butyl alcohol is used with respect to all solvents, the ability to dissolve the resin and the viscosity stability of the coating composition. In addition, the present inventors have found that the residual solvent amount of the whole solvent is reduced without impairing properties such as drying properties, and the present invention has been completed.

Next, the coating composition of the present invention will be described.

<About the coating composition of this invention>
(resin)
The resin that can be used in the present invention is not particularly limited as long as it is a resin that basically dissolves in a solvent containing an alcohol component, and is an acrylic resin, shellac resin, polyurethane resin, cellulose resin, polyester resin, styrene-acrylic resin. , Ethylene-acrylic resin, styrene-maleic acid-based resin, water-soluble resin containing a hydroxyl group (polyvinyl alcohol-based polymer resin, ethylene-vinyl alcohol-based copolymer resin, etc.) and the like can be used. Moreover, what has a carboxyl group in a molecule | numerator and can be made aqueous by basic compounds, such as ammonia, a highly volatile amine compound, an alkanolamine compound, an alkali metal salt, can also be used.

Among these, a high hydrogen bonding resin is a preferable example. The high hydrogen bond resin means a resin having a high content of hydrogen bond groups or ionic groups in the resin, and is not particularly limited, but usually the number of hydrogen bond groups or ionic groups per unit weight of the resin. A high hydrogen bonding resin satisfying a weight percentage of 5% to 60% can be used. Examples of the hydrogen bonding group of the high hydrogen bonding resin include a hydroxyl group, an amino group, a thiol group, a carboxyl group, a sulfonic acid group, and a phosphoric acid group. The ionic group includes a carboxylate group, a sulfonic acid ion group, and a phosphate ion. Group, ammonium group, phosphonium group and the like. Among the hydrogen bonding group or ionic group of the high hydrogen bonding resin, particularly preferable examples include a hydroxyl group, an amino group, a carboxyl group, a sulfonic acid group, a carboxylate group, a sulfonic acid ion group, and an ammonium group. .

Specific examples of the high hydrogen bonding resin include, for example, ethylene-vinyl alcohol copolymer, polyvinyl alcohol polymer; hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, amylose, amylopectin, pullulan, curdlan, xanthan, chitin, chitosan. Polysaccharides such as cellulose, pullulan, chitosan, etc .; polyacrylic acid, sodium polyacrylate, polybenzenesulfonic acid, sodium polybenzenesulfonate, polyethyleneimine, polyallylamine, its ammonium salt, polyvinyl thiol, polyglycerin Etc. Among the high hydrogen bonding resins, polyvinyl alcohol polymer resins and ethylene-vinyl alcohol copolymer resins which are water-soluble resins containing a hydroxyl group are preferable. In the present invention, the polyvinyl alcohol polymer resin refers to a homopolymer of polyvinyl alcohol and a resin comprising a copolymer having a polyvinyl alcohol skeleton in the main chain, and an ethylene-vinyl alcohol copolymer resin. The term “resin” refers to a resin made of a copolymer having an ethylene-vinyl alcohol skeleton in the main chain.

The content of the resin in the coating composition is not particularly limited, but is usually in the range of 1 to 50% by mass of the total mass of the coating composition and in the range of 1 to 30% by mass of the total mass. Is preferred.

(solvent)
In this invention, 1-50 mass% of tertiary butyl alcohol (t-butyl alcohol) is contained with respect to the total amount of solvent, It is characterized by the above-mentioned. It is more preferable to contain 3-40 mass%. It is more preferable to contain 5-30 mass%. When the content of tertiary butyl alcohol is less than 1% by mass, the effect of adding tertiary butyl alcohol does not appear. In the case of 50 mass% or more, the compatibility with the resin may be inferior, which is not preferable.

Next, examples of alcohol components other than tertiary butyl alcohol that can be used in the present invention include methanol, ethanol, isopropyl alcohol, normal (n-) propanol, 1-methoxypropanol, 2-methoxypropanol, and 1-butanol. Lower alcohols having 1 to 4 carbon atoms such as 2-butanol and isobutyl alcohol, polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol and glycerin, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monoacetate, diethylene glycol monomethyl ether And dipropylene glycol monomethyl glycol or N- methylpyrrolidone.

Especially, as above-mentioned, it is preferable to use C1-C3 lower alcohols, such as methanol, ethanol, isopropyl alcohol, and normal (n-) propanol, with tertiary butyl alcohol. In this invention, it is especially preferable that a coating composition contains tertiary butyl alcohol 5-30 mass% with respect to the total amount of solvents, and C1-C3 alcohol.

Other solvents are not particularly limited as long as the compatibility with the resin can be ensured and good drying properties can be maintained, and various solvents can be used. Acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, ethyl butyl Ketones such as ketones, esters such as methyl acetate, ethyl acetate, normal (n-) propyl acetate, isopropyl acetate, normal (n-) butyl acetate, butyl acetate, and isobutyl acetate can be used.

In the present invention, water can also be used as a solvent that does not burden the environment. When water is used, it is not particularly limited, but it can usually be used in a state where the mass ratio of alcohol component / water is 30/70 to 70/30. In a preferred embodiment, the resin is a polyvinyl alcohol polymer resin or an ethylene-vinyl alcohol copolymer resin, the solvent contains an alcohol component containing at least tertiary butyl alcohol and water, and the alcohol component / water The content ratio (mass ratio) of is 30/70 to 70/30.

(Inorganic layered compound)
The coating composition of this invention may contain the inorganic layered compound as needed. By adding an inorganic layered compound, gas permeation can be suppressed due to the labyrinth effect when used as a gas barrier layer. As the inorganic stratiform compound, an inorganic stratiform compound that swells and cleaves in the dispersion medium is preferably used. Examples thereof include a smectite group, a hydrated silicate mineral, a vermiculite group, and a mica group.

Specific examples of the inorganic layered compound include kaolinite, nacrite, dickite, halloysite, hydrous halloysite, antigolite, chrysotile, pyrophyllite, montmorillonite, beidellite, saponite, hectorite, soconite, stevensite, tetracite. Examples include lyric mica, sodium teniolite, muscovite, margarite, talc, vermiculite, phlogopite, xanthophyllite, chlorite, and the like. These may be natural products or synthetic products. Also, scaly silica can be used. These may be used alone or in combination of two or more.

Among these, use of montmorillonite is preferable from the viewpoint of gas barrier performance and printability when used in a coating composition.

In the coating composition, the mass ratio (solid content mass ratio) between the resin and the inorganic stratiform compound is not particularly limited, but the resin / inorganic stratiform compound ratio is usually in the range of 30/70 to 95/5, preferably Is in the range of 30/70 to 50/50. If the mass ratio of the inorganic layered compound is decreased, sufficient oxygen barrier properties may not be obtained. On the other hand, if the amount is too large, the coating strength and the adhesion to other layers tend to be insufficient. In the coating composition, the resin is an ethylene-vinyl alcohol copolymer, and the mass ratio of the ethylene-vinyl alcohol copolymer and the inorganic layered compound is 30/70 to 50/50. preferable.

In the above coating composition, the total content of the resin and the inorganic layered compound is usually in the range of 1 to 50% by mass of the total mass of the coating composition, and in the range of 1 to 30% by mass of the total mass. Is preferred.

(Coloring agent)
The coating composition of the present invention can also be used as an aqueous printing ink composition by further containing a colorant.

As the colorant used in the present invention, dyes, inorganic pigments, organic pigments and extender pigments generally used in printing inks, paints and the like can be used. Examples of usable dyes include various dyes such as azo dyes, anthraquinone dyes, indigo dyes, phthalocyanine dyes, carbonyl dyes, quinoneimine dyes, methine dyes, quinoline dyes, and nitro dyes. Further, usable inorganic pigments include titanium oxide, bengara, antimony red, cadmium red, cadmium yellow, cobalt blue, bitumen, ultramarine blue, carbon black, graphite and the like, and organic pigments include soluble azo pigments and insoluble azo pigments. Azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, condensed polycyclic pigments, and the like.

Further usable extender pigments include calcium carbonate, kaolin, clay, barium sulfate, aluminum hydroxide, talc and the like, and these can be used alone or in combination of two or more.

(Other additives)
In addition, the coating composition of the present invention includes various additives such as a pigment dispersant, an antiblocking agent, an antifoaming agent, a crosslinking agent, a wettability improver, a plasticizer, and a thickener, and the properties of the coating composition. You may mix | blend an appropriate quantity in the range which does not impair.

<The manufacturing method of the coating composition of this invention>
Examples of the method for producing the coating composition of the present invention using the above-described constituent materials include (1) a solution in which a resin is dissolved in the above solvent, an inorganic layered compound (previously swollen and cleaved in a dispersion medium such as water). And (2) after the inorganic layered compound is swollen and cleaved in a dispersion medium such as water, using a stirrer or a dispersing device. Examples thereof include a method in which a solution obtained by dissolving a resin in the above solvent is added to and mixed with a dispersion obtained by cleaving and dispersing an inorganic layered compound using a stirring device or a dispersion device. There is no particular limitation on the addition of the colorant and other additives, and the addition time can be appropriately selected in consideration of the dispersibility of the colorant and other additives.

The stirring device and the dispersion device are not particularly limited as long as they are ordinary stirring devices and dispersion devices, and these can be used to uniformly disperse the inorganic layered compound in the dispersion liquid. From the viewpoint of obtaining a layered compound dispersion, it is preferable to use a high-pressure disperser, an ultrasonic disperser or the like. Examples of the high-pressure disperser include a nanomizer (trade name, manufactured by Nanomizer), a microfluidizer (trade name, manufactured by Microfridex), an optimizer (trade name, manufactured by Sugino Machine), and DeBee (trade name, Bee). And Niro Soabi homogenizer (trade name, manufactured by Niro Soabi) and the like. It is preferable to perform the dispersion treatment at 100 MPa or less as the pressure condition of these high-pressure dispersers. When the pressure condition exceeds 100 MPa, the inorganic layered compound tends to be crushed and the target gas barrier property may be lowered.

<The manufacturing method and laminating method of the printed matter which used the coating composition of this invention as an aqueous printing ink composition>
The coating composition of the present invention obtained as described above is not particularly limited and can be suitably used for various applications. Especially, when a coating composition contains a coloring agent, it can be conveniently used as an aqueous printing ink composition. Then, the manufacturing method of the printed matter which uses the coating composition of this invention as a water-based printing ink composition, and the lamination method are demonstrated.

First, as the plastic film on which the coating composition of the present invention is printed, various plastic films such as polyolefin, modified polyolefin, polyester, nylon and polystyrene can be used. Among them, the corona discharge-treated film has a carbonyl group, and a better printed product can be obtained.

The coating composition of the present invention can be printed by a flexographic or gravure printing method using a known flexographic printing machine or gravure printing machine.

Furthermore, as a method for laminating the printed matter obtained by the above printing method, an extrusion laminating method and a dry laminating method can be used.

Here, the extrusion laminating method is performed by applying a titanate-based, isocyanate-based, imine-based, or polybutadiene-based anchor coating agent on the surface of the printed material as necessary, and then using a conventionally known extrusion laminating machine to melt polymer. In addition, a molten resin can be used as an intermediate layer and laminated with other materials in a sandwich shape.

As the molten resin used in the extrusion laminating method, conventionally used resins such as low density polyethylene, ethylene-vinyl acetate copolymer, and polypropylene can be used. Among them, the effect of the present invention is enhanced in combination with low-density polyethylene that is oxidized during melting and easily generates carbonyl groups.

Next, in the dry laminating method, an aqueous, solvent-based or solvent-free isocyanate-based adhesive is applied to the surface of the printed material, and then a film-like polymer is pasted by a conventionally known dry laminating machine. It is a method to do.

Polyethylene, polypropylene, etc. can be used as the film-like polymer used in the dry laminating method. Especially in the laminated product used for the retort application, the plastic film to be bonded to the base material for imparting hot water resistance is used. It can also be laminated with an aluminum foil in between.

In view of safety and hygiene, environmental problems, and the like, it is preferable to use an aqueous or solventless adhesive in order to obtain a laminated product without using any organic solvent in the production process.

The laminated product obtained from the above method has a high laminate strength, and can be applied to boil and retort applications. Also, the coating composition of the present invention and an aqueous or solvent-free laminate are used. By combining with an adhesive, a laminated product can be suitably obtained from the viewpoint of health and safety, environmental problems, etc. without using any organic solvent in the production process.

<Method for producing gas barrier composite film using coating composition of the present invention>
Furthermore, the coating composition of this invention can be used suitably also as a gas barrier layer of a gas barrier composite film. The structure of the gas barrier composite film is not particularly limited, but as a preferred form, a gas barrier layer and a sealing material layer (sealant layer) are laminated in this order on the printed surface side of the printed base film to form a packaging bag. And in this packaging bag, the form which a gas barrier layer becomes inside rather than a printing surface is mentioned. With such a structure, it is possible to prevent the solvent remaining on the printing surface from moving into the inside of the packaging bag, and it is possible to sufficiently suppress the entry of gas or the like from the outside of the packaging bag. .

The gas barrier composite film may have other layers other than the film, gas barrier layer, and sealing material layer, and may have, for example, an adhesive layer.

As the base film, a plastic film that can be conventionally used as a film for laminating can be used. Specifically, plastic films made of polyolefin, modified polyolefin, polyester, nylon, polystyrene, etc., and two types of these plastics The composite plastic film etc. which are obtained by using above can be mentioned. These plastic films are more preferably those subjected to corona discharge treatment or surface coating treatment within a range that does not impair the transparency of the resulting gas barrier composite film.

Next, the printing ink composition used in order to print on the film which comprises a gas barrier composite film is demonstrated.
As the printing ink composition, a conventional ink composition that can be printed on a plastic film can be used, and both organic solvent-based and aqueous printing inks for laminating can be used. As the ink for laminating, the type that uses polyurethane resin, which is excellent in adhesiveness to film, pigment dispersibility, laminating suitability, etc., is the mainstream, and aromatic organic solvent to give good printability. In recent years, environmentally friendly inks that do not use aromatic and ketone organic solvents as much as possible have been used. Examples of such a printing ink composition comprising a non-aromatic organic solvent include, for example, Japanese Patent Publication No. 07-113098 (printing ink composition for non-aromatic organic solvent-based laminate containing pigment and polyurethane resin), No. 07-324179 (printing ink composition containing pigment, polyurethane resin, non-aromatic / non-ketone organic solvent) and the like can be mentioned.

Further, as a printing ink composition for laminating, an aqueous type ink is also being used. For example, JP 06-155694 (Aqueous laminating printing ink composition containing a pigment, an acrylic aqueous binder resin, and a hydrazine crosslinking agent) Product), and JP-A 06-206972 (printing ink composition for water-based laminating containing pigment, water and polyurethane binder resin), and the like. In addition, since a completely water-based printing ink composition using only water as a solvent has low printability for a plastic film and is difficult to be practically used, a water-based laminating printing ink composition is usually a water-based printing ink composition. In addition, a combination of water-miscible organic solvents such as lower alcohols, polyhydric alcohols and derivatives thereof is included.

In this way, as environmentally friendly inks, replacement with printing inks using organic solvents with low toxicity and water-based printing inks is proceeding as much as possible, and the printing work environment and organic solvents permeate the printing substrate film to the atmosphere. In consideration of evaporation inside, the above-mentioned environmentally friendly ink is preferably used for food hygiene.

In addition, as described above, the coating composition of the present invention containing a colorant can also be used as an aqueous printing ink composition. By using the coating composition of the present invention as an aqueous printing ink composition in addition to the gas barrier layer, it is preferable in that the residual solvent in the gas barrier composite film can be further reduced and the gas barrier effect can be further enhanced.

Next, examples of the sealing material layer include those obtained by using a hot-melt resin made of low-density polyethylene, ethylene-vinyl acetate copolymer, polypropylene, or the like. The sealing material layer can be formed by melt-bonding or bonding as a film depending on the form of the laminate.

Further, in the gas barrier composite film, an adhesive and / or an anchor coating agent is provided between the printing surface side and the gas barrier layer and / or between the gas barrier layer and the sealing material layer in order to improve the adhesion between the layers. What adhere | attaches using the contact bonding layer which consists of is preferable. Examples of the adhesive include isocyanate-based, urethane-based, and acrylic-based various laminating adhesives, and examples of the anchor coating agent include titanium-based, isocyanate-based, imine-based, and polybutadiene-based laminates. An anchor coating agent can be used. Note that these adhesives and anchor coat agents may contain an adhesion modifying material such as a crosslinking agent.

A method for producing a gas barrier composite film using the coating composition of the present invention and the above laminated material will be described.
A printing ink composition for laminating is printed on a plastic film using a known gravure printing machine, flexographic printing machine or the like. Next, after applying an adhesive or an anchor coating agent as necessary, the coating composition of the present invention for forming a gas barrier layer is applied and dried by heating. As the coating method of the coating composition of the present invention, conventional coating methods such as a roll coating method using a gravure cylinder, a doctor knife method, an air knife / nozzle coating method, a bar coating method, a spray coating method, a dip coating method, etc. A construction method can be used, and these methods may be combined.

The thickness of the coated gas barrier layer is preferably 0.1 to 5 μm, and more preferably 0.1 to 0.5 μm in that a highly transparent gas barrier layer can be formed. If the gas barrier layer is less than 0.1 μm, it is difficult to obtain the target gas barrier property and the shielding effect of the organic solvent. On the other hand, if it exceeds 5 μm, the gas barrier property may not be improved, and sufficient transparency is obtained. It becomes difficult.

Next, after forming an adhesive layer as necessary, a gas barrier is formed by a conventionally known laminating method such as an extrusion laminating method in which a resin for forming a sealing material layer is melt-pressed or a dry laminating method in which a sealant film is bonded with an adhesive. A gas barrier composite film of the present invention can be produced by forming a sealing material layer on the layer.

The solvent contained in the anchor coat agent or adhesive used as necessary between the printing layer side and the gas barrier layer is blocked by the gas barrier layer and hardly passes through the sealing material layer. There is a possibility that a solvent contained in an anchor coat agent or an adhesive used as needed between the sealing material layer and the sealing material layer.
Therefore, the anchor coat agent and the adhesive used between the gas barrier layer and the sealing material layer are a solventless type, an aqueous type, or a volatile organic solvent type using a solvent that can be volatilized mostly during the bonding process. It is preferable.

Finally, a method for making a bag using a gas barrier composite film and the use of the resulting packaging bag will be described.
As a method for making a bag of a gas barrier composite film, a heat sealer or the like is used, and the gas barrier composite film is folded in half and sealed on two sides, or two gas barrier composite films are stacked and three sides are melted. After sealing or making a bag shape first, the contents can be packed, the remaining side is sealed, and used as a sealed packaging bag.

Packaging bags produced in this way are required to have high gas barrier properties, and can be used for applications where residual solvents and eluents from pigments need not migrate into the bag. It can be suitably used as a packaging bag.

The coating composition of the present invention has a low residual solvent amount after coating and excellent gas barrier properties. Therefore, since the amount of residual solvent can be greatly reduced without impairing the quality and properties after coating the coating composition, the surface to be printed on the printing substrate film used in applications where it is necessary that the residual solvent does not migrate into the bag. It can be suitably used as a printing ink composition for printing, laminating, etc., a gas barrier layer of a gas barrier composite film, or a material for a laminated product.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these, unless it deviates from the meaning and application range. In the following description, “%” represents “mass%”, and “part” represents “part by mass”.

In Examples, Comparative Examples and Tables, “IPA” represents iso (iso-) propyl alcohol, “TBA” represents tertiary butyl (t-butyl) alcohol, and “NPA” represents n-propyl alcohol. .

(Liquid A)
To 60 parts of a mixed solvent containing 50% purified water, 47% iso (iso-) propyl alcohol (IPA) and 3% tertiary butyl alcohol, EVOH (ethylene-vinyl alcohol copolymer resin, manufactured by Nippon Synthetic Chemical Co., Ltd., product) Name: Soarnol D-2908) 30 parts was added, heated to 80 ° C. with stirring, and allowed to react for about 2 hours. Thereafter, the mixture was cooled to obtain a substantially transparent mixed liquid having a solid content of 30%.

(Liquid B)
5 parts of montmorillonite (trade name: Kunipia F, manufactured by Kunimine Kogyo Co., Ltd.), which is an inorganic layered compound, was added to 95 parts of purified water while stirring and sufficiently dispersed with a high-speed stirrer. Then, it kept at 40 degreeC for 1 day.

(C liquid)
It was the same as Liquid A except that purified water was 50%, IPA was 40%, and tertiary butyl alcohol was 10% to obtain a substantially transparent mixed liquid having a solid content of 30%.

(Liquid D)
Except for using purified water 50%, IPA 20%, and tertiary butyl alcohol 30%, it was the same as liquid A, and an almost transparent mixed liquid having a solid content of 30% was obtained.

(E liquid)
Except for purified water 50% and IPA 50%, it was the same as liquid A, and an almost transparent mixed liquid having a solid content of 30% was obtained.

Example 1
To 60 parts of a mixed solvent of 50% purified water, 47% IPA, and 3% tertiary butyl alcohol, 4 parts of the above-mentioned A solution was added and mixed thoroughly. Further, 36 parts of Liquid B was added to this mixture while stirring at high speed, and dispersion treatment was performed with a high-pressure dispersion apparatus at a pressure of 50 MPa. The coating solution thus obtained was a uniform and stable dispersion.

(Example 2)
To 60 parts of a mixed solvent of 50% purified water, 40% IPA, and 10% tertiary butyl alcohol, 4 parts of the above-mentioned C solution was added and sufficiently mixed with stirring. Further, 36 parts of Liquid B was added to this mixture while stirring at high speed, and dispersion treatment was performed with a high-pressure dispersion apparatus at a pressure of 50 MPa. The coating solution thus obtained was a uniform and stable dispersion.

(Example 3)
To 60 parts of a mixed solvent of 50% purified water, 20% IPA, and 30% tertiary butyl alcohol, 4 parts of the above D solution was added and mixed thoroughly. Further, 36 parts of Liquid B was added to this mixture while stirring at high speed, and dispersion treatment was performed with a high-pressure dispersion apparatus at a pressure of 50 MPa. The coating solution thus obtained was a uniform and stable dispersion.

Example 4
To 60 parts of a mixed solvent of 50% purified water, 40% IPA, and 10% tertiary butyl alcohol, 4 parts of the above-mentioned C solution was added and sufficiently mixed with stirring. Further, 36 parts of a suspension in which 20% cyanine blue pigment was dispersed in purified water was added to this mixture while stirring at high speed, and the mixture was subjected to dispersion treatment at a pressure of 50 MPa with a high-pressure dispersion apparatus. The resulting ink coating composition was a uniform and stable dispersion.

(Example 5)
To 60 parts of a mixed solvent of 50% purified water, 40% IPA, and 10% tertiary butyl alcohol, 4 parts of the above-mentioned C solution was added and sufficiently mixed with stirring. Furthermore, 36 parts of purified water was added to this mixture while stirring at high speed. The coating solution thus obtained was a uniform and stable dispersion.

(Comparative Example 1)
4 parts of the previous E solution was added to 60 parts of a mixed solvent of 50% purified water and 50% IPA, and the mixture was sufficiently stirred and mixed. Further, 36 parts of Liquid B was added to this mixture while stirring at high speed, and dispersion treatment was performed with a high-pressure dispersion apparatus at a pressure of 50 MPa. The coating solution thus obtained was a uniform and stable dispersion.

(Comparative Example 2)
To 60 parts of a mixed solvent of 50% purified water and 50% NPA, 4 parts of the above solution A was added and sufficiently mixed with stirring. Further, 36 parts of Liquid B was added to this mixture while stirring at high speed, and dispersion treatment was performed with a high-pressure dispersion apparatus at a pressure of 50 MPa. The coating solution thus obtained was a uniform and stable dispersion.

Table 1 shows a summary of the composition of the coating liquid / ink coating composition of each Example and Comparative Example.

The coating liquid and ink coating compositions of Examples and Comparative Examples were filtered through a 255 mesh filter, and OPP (biaxially oriented polypropylene) film (Toyobo Co., Ltd., Pyrene P-2161 ( Product name), thickness 25 μm).

(Coating method / conditions)
Coating machine: Gravure proofing machine
Coating speed: 27m / min
Plate: Direct 175 line solid plate Drying temperature: 100 ° C (Air volume 80%)
Base material: Emblem ON # 12 (biaxially stretched nylon film, manufactured by Unitika Ltd.)

(Residual solvent measurement)
Residual solvent amount: Each printed matter (0.2 m ² ) obtained by applying the coating liquid / ink coating compositions of Examples and Comparative Examples by the above method was put in a 500 ml flask, and the temperature was 10 ° C. The solvent remaining in the printed material was vaporized by heating in an oven for 1 minute, 1 ml of gas was collected from the flask, and the amount of residual solvent per unit area (mg / m ² ) was measured by gas chromatography. The results are shown in Table 2.

(OTR value (oxygen permeability))
(Evaluation methods)
Each printed matter obtained by applying the coating liquid of Examples and Comparative Examples (excluding Example 4 used as a coating composition for ink) by the above method as a sample, according to JIS K7126 B method, The oxygen permeability (OTR value, unit: cm ³ / m ² · day · kPa) was measured using an oxygen permeability measuring device (manufactured by Mocon; trade name: OX-TRAN100). The measurement conditions were 23 ° C. and 80% RH (relative humidity). The results are shown in Table 3.

As shown in Table 2, in the printed matter obtained from the composition of the example, compared with the printed matter obtained from the composition of Comparative Examples 1 and 2 not containing tertiary butyl (t-butyl) alcohol, It can be seen that the amount of the solvent remaining in is greatly reduced. Moreover, as shown in Table 3, the OTR values of the printed materials obtained from the compositions of the examples are smaller than the printed materials obtained from the compositions of Comparative Examples 1 and 2, and the coating compositions of the examples are more It turns out that oxygen is difficult to pass through and has excellent gas barrier properties. Thus, the coating layer obtained from the coating composition of the present invention has a small amount of residual solvent and excellent gas barrier properties.

The coating composition of the present invention is used in applications where the residual solvent does not need to be transferred into the bag, and is used for printing ink compositions including for surface printing and laminating printed on a printing substrate film, and for gas barrier composite films. It can be suitably used as a gas barrier layer or a laminate material. In particular, it can be suitably used as a packaging material for foods and pharmaceuticals.

Claims (9)

In the coating composition containing a resin and a solvent, the solvent contains an alcohol component containing at least tertiary butyl alcohol, and the solvent contains tertiary butyl alcohol in an amount of 1 to 50% by mass based on the total amount of the solvent. A coating composition characterized by The coating composition according to claim 1, wherein the resin is a high hydrogen bonding resin. The coating composition according to claim 2, wherein the high hydrogen bonding resin is a polyvinyl alcohol polymer resin or an ethylene-vinyl alcohol copolymer resin. The resin is a polyvinyl alcohol polymer resin or an ethylene-vinyl alcohol copolymer resin,
4. The solvent according to claim 1, wherein the solvent contains an alcohol component containing at least tertiary butyl alcohol and water, and the mass ratio of the alcohol component / water is 30/70 to 70/30. A coating composition according to claim 1. The coating composition as described in any one of Claims 1-4 containing an inorganic layered compound. The coating composition as described in any one of Claims 1-5 which contains tertiary butyl alcohol 3-40 mass% with respect to the total amount of solvents. The coating composition as described in any one of Claims 1-6 which contains tertiary butyl alcohol 5-30 mass% with respect to the total amount of solvents. The coating composition according to any one of claims 1 to 7, wherein the tertiary butyl alcohol contains 5 to 30 mass% of the total amount of solvent and an alcohol having 1 to 3 carbon atoms. Furthermore, the coating composition as described in any one of Claims 1-8 containing a coloring agent.