JP3649244B1 - Water-based coating agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To have excellent low-temperature film-forming properties without using a film-forming auxiliary comprising an organic solvent, excellent adhesion to a substrate, particularly a polyester film, and heat resistance, water resistance, solvent resistance, and transparency. To provide an aqueous coating agent capable of forming a coating layer excellent in properties and the like.
SOLUTION: A water-dispersible polyurethane resin containing 15 to 35% by weight of an aromatic cyclic structural unit and a hydrophobic polyester polyol containing 20 to 50% by weight of an aromatic cyclic structural unit and being liquid at normal temperature. An aqueous coating agent comprising: an aqueous dispersion in which resin particles containing a hydrophobic polyether polyol are dispersed in water; and a crosslinking agent capable of reacting with a hydroxyl group.
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Description

  The present invention relates to an aqueous coating agent. More specifically, when manufacturing a primer coating agent used for the purpose of modifying the surface of a plastic film such as polyester resin, polypropylene resin, polyamide resin, etc. and imparting easy adhesion, an aluminum-deposited plastic film, the plastic film The present invention relates to an anchor coating agent used for the purpose of improving the adhesion of aluminum to a vapor-deposited layer, and other water-based coating agents applicable as a surface treatment agent for other paints, inks, fibers and leathers.

Biaxially stretched polyester films (for example, polyethylene terephthalate films, generally referred to as PET films) are excellent in electrical insulation, transparency, dimensional stability, toughness, etc. It is used in a wide range of fields such as magnetic tape, metal vapor deposition film, and various packaging materials.
However, these biaxially stretched polyester films have poor surface adhesion because the molecular chains of the resin constituting the film are highly oriented, and printing inks, magnetic paints coated on such films, There is a problem of poor adhesion to vapor-deposited metals and adhesives.

  In order to improve such a problem, as a method for activating the surface of the polyester film and improving the adhesiveness with printing ink or the like, a means for subjecting the film surface to corona treatment, ultraviolet irradiation treatment, plasma treatment, or flame treatment is generally used. Has been applied. However, although the adhesion is improved by these methods, the activity decreases with time. Accordingly, these means for activating the film surface are not always satisfactory.

  As another method for improving the adhesion of the film surface, an etching method has been proposed in which the surface is swollen or dissolved using a chemical such as acid, alkali, trichloroacetic acid or phenols. This is intended to decompose and dissolve the crystal orientation in the vicinity of the film surface, and at the same time to reduce the cohesiveness and increase the adhesiveness, and the effect is the most reliable means. However, some of the drugs used here are harmful, and there are problems associated with danger in handling.

  As a means similar to this method, using a coating agent called a primer coating agent or an anchor coating agent, it is said that a coating layer (primer layer, anchor layer or undercoat layer, etc.) that is different from the base material on the film in advance. There is a method of forming a thin film. In the prior art, a method of applying a solvent-based coating agent dissolved in an organic solvent to the surface layer of a film was generally used, but recently, from the viewpoint of safety and hygiene, aqueous coating agents (such as aqueous primer coating agents or aqueous anchor coating agents) are used. It is said that the mainstream. In particular, an aqueous polyurethane resin composition having excellent adhesion to various substrates has been studied as such an aqueous coating agent.

  Plastic films having a coating layer formed using such an aqueous coating agent are used in various applications. Of these, polyester films are widely used as food packaging films because of their transparency and toughness. In such applications, the polyester film is rarely used alone, and after printing, it is generally used as a laminated film laminated with various films using an adhesive. Therefore, the plastic film on which the coating layer is formed is required to be excellent in processability such as printing and laminating under various conditions and durability. In other words, the ink applied on the coating layer formed on the plastic film, and various adhesives such as solvent-based resin composition and aqueous resin composition are used. The applied coating layer is required to have excellent solvent resistance, water resistance, heat resistance, and the like. In order to meet these demands, the aqueous coating agent is mainly used in combination with various crosslinking agents.

  In recent years, various functions for films have been demanded due to diversification of film applications, and in particular, for the purpose of improving the gas barrier performance of packaging materials, for example, a coating layer such as polyvinylidene chloride or a vapor deposition layer of aluminum is used. A formed plastic film or the like is used as a component of a packaging material. At that time, for the purpose of improving the adhesion to the vapor deposition layer of polyvinylidene chloride or aluminum, a method of applying a coating agent on the plastic surface in advance and providing a coating layer is performed. In that case, in order to express high gas barrier performance, it is required that such a coating layer be uniformly applied. For this purpose, the coating agent can be applied to various coating methods, and even under various conditions. It is required to always obtain a uniform coating layer.

  As a method of applying the coating agent to the plastic film, an in-line coating method in which a coating agent is applied during the biaxial stretching process of the plastic film, and then a lateral stretching process is performed, and after the biaxial stretching process, winding is performed. An off-line coating method is employed in which a coating layer is formed by applying a coating agent to a taken plastic film and drying it.

  In the in-line coating method, since the coating agent is generally applied before the crystal orientation is completed during the biaxial stretching process of the plastic film, the adhesion between the base film and the coating layer becomes strong. For example, in the case of a PET film, a stretching process is further performed at a temperature of 150 ° C. or higher. At that time, the base resin and the crosslinking agent contained in the coating agent react abruptly to cure the coating layer, making it impossible for the coating layer to follow the stretched substrate, resulting in cracks in the coating layer. There is a problem that occurs.

  In the off-line coating method, since it is necessary to maintain the dimensional stability of the substrate, the drying step is generally performed at a low temperature of 100 ° C. or lower. Therefore, a solvent-based coating agent that can form a hard and uniform coating layer at low temperatures has been used, but it is not preferable due to safety problems and environmental pollution problems, and it can also be used for off-line coating methods. The development of a coating agent was eagerly desired.

Various proposals have been made to improve these problems.
For example, an aqueous resin composition comprising an aqueous polyester urethane resin having a pendant carboxyl group neutralized with ammonia or an organic amine in a high molecular weight product obtained from a polyester polyol having an aromatic cyclic structure and a polyisocyanate compound. It is disclosed that a primer coating agent having excellent water resistance and blocking resistance can be provided (for example, see Patent Document 1).

According to such a technique, a hard aqueous polyurethane resin can be obtained by using a polyester having an aromatic cyclic structure, but a uniform coating layer is formed due to the high glass transition temperature of the polyurethane resin. To obtain it, a film forming process at a high temperature is required.
In practice, it is often used in combination with various crosslinking agents for the purpose of improving the solvent resistance and heat resistance of the coating layer. In that case, in the film stretching process in the in-line coating method, There is a problem that it is difficult to form a uniform coating layer because of poor conformity to the film.

In order to solve such problems and to form a uniform coating layer, generally a high boiling point organic solvent is used as a film-forming aid, and a method of plasticizing the main component resin in the coating agent is adopted. Has been.
As a method of using this film-forming aid, for example, a hydrophilic fusing agent having an oxyalkylene glycol derivative having a boiling point of 80 to 270 ° C. is used as a film-forming aid, and the minimum film-forming temperature (MFT) is lowered. Furthermore, a polyurethane-based emulsion coating agent composition that improves film-forming properties at low temperatures has been proposed (see, for example, Patent Document 2).
In addition, a polypropylene film for metal vapor deposition that improves adhesion to a substrate by mixing with a polyester urethane resin using a water-soluble organic solvent typified by N-methyl-2-pyrrolidone as a film-forming aid, and A metal-vaporized polypropylene film has been proposed (see, for example, Patent Document 3).

However, these methods using organic solvents inherently have problems such as harm to the human body and safety such as ignition, and are substantially free of organic solvents, resulting in low film-forming properties. There is a need for excellent coating agents. In addition, development of a coating agent having excellent adhesion between a coating agent and a substrate has been demanded when surface modification of a hardly adhesive plastic film represented by polypropylene, nylon and polyester film is performed.
Furthermore, when an organic solvent is used as a film-forming aid, the film-forming aid remains in the coating film when the drying conditions at a relatively low temperature of 100 ° C. or less, such as the above-mentioned offline coating, are required, and the surface hardness There is a problem that the wear resistance and blocking resistance are lowered, and the film-forming aid has a high hydrophilicity, so that the water resistance is lowered unless the coating film is sufficiently dried. It was.

Further, as a technique for improving adhesiveness while maintaining heat resistance, an aqueous polyurethane dispersion obtained by adding an adhesion improving polymer to a polyurethane resin and dispersing it in water has been proposed (see, for example, Patent Document 4). .)
In this aqueous dispersion, adhesion and heat resistance are improved by adding a resin having a softening temperature of 80 to 130 ° C. to the polyurethane resin as an adhesion improving polymer. When the dispersion was applied to the in-line coating method, the substrate followability in the stretching process was lowered, and as a result, it was difficult to obtain a uniform film having no coating film defects. In addition, when applied to an off-line coating method having a low processing temperature, the film forming property of the aqueous dispersion is insufficient, and as a result, it is difficult to obtain a uniform film having no coating film defects.

Japanese Examined Patent Publication No. 8-22900 (left column on page 1 to right column on page 2) Japanese Examined Patent Publication No. 63-14748 (left column on page 1 to right column on page 2) JP 2000-108262 A (second page left column claim 1 to page 2 right column paragraph "0005") Japanese Patent Laid-Open No. 5-230364 (left column on page 1 to right column on page 2)

  The object of the present invention is to provide excellent film-forming properties without using a film-forming aid made of an organic solvent even when applied at a relatively low temperature such as room temperature, and to adhere to a substrate, particularly a polyester film. An object of the present invention is to provide an aqueous coating agent capable of forming a coating layer having excellent properties.

  In addition, another object of the present invention is to provide a film in a stretching step that is continuously carried out even when applied in the middle of the film stretching step in the in-line coating method that is processed at a high temperature of 150 ° C. or higher, for example. An object of the present invention is to provide an aqueous coating agent that can form a coating layer that has excellent followability to deformation and does not generate cracks.

  As a result of intensive studies to solve the above problems, the present inventors have found that resin particles containing a water-dispersible polyurethane resin having an aromatic cyclic structure and a polyester polyol or polyether polyol that is liquid at room temperature are water. By using an aqueous dispersion formed by dispersing in water and an aqueous coating agent containing a crosslinking agent capable of reacting with a hydroxyl group, the film-forming property at the time of coating at a relatively low temperature can be improved. It has been found that good film-forming properties can be obtained even in an off-line coating method.

In addition, by using a polyester polyol or polyether polyol having an aromatic cyclic structure in the molecule as a polyester polyol or polyether polyol that is liquid at normal temperature, it was possible to improve the adhesion particularly to the polyester film. .
In addition, even if a coating agent is applied during the film stretching process as is normally done in the in-line coating method by such a technique, the formed coating layer has a followability to film deformation in the further stretching process. It was found that it was excellent and cracks were not generated and a good coating layer was obtained.

  Such a low-temperature film-forming property improving effect is that the water-dispersible polyurethane resin having an aromatic cyclic structure is plasticized by a polyester polyol or polyether polyol having an aromatic cyclic structure that is liquid at the normal temperature. It is thought to be attributed to. However, a sufficient amount of the polyester film having an aromatic cyclic structure that is liquid at room temperature, sufficient to express the effect of improving the low-temperature film-forming property, is contained in the aqueous dispersion. Faced with the problem of lowering the blocking resistance.

As a result of investigations to solve this problem, the polyester polyol having an aromatic cyclic structure that is liquid at room temperature is included in the aqueous dispersion, but it is intended to have water dispersibility by itself. It has been found that by using a hydrophobic material which is not present, good low-temperature film-forming properties and heat resistance are not impaired even if the amount contained in the aqueous dispersion is relatively small.
If a polyester polyol having an aromatic cyclic structure is used, the polyester polyol having an aromatic cyclic structure is formed from the water-dispersible polyurethane resin that is stably present in water. Even if the amount of the polyester polyol having the aromatic cyclic structure is reduced, the amount is taken into the dispersed particles and considered to exist in a form of being wrapped in the water-dispersible polyurethane resin layer. It is presumed that the effect of improving the low-temperature film-forming property is affected.

In addition, when forming dispersed particles containing both the water-dispersible polyurethane resin and the polyester polyol having the aromatic cyclic structure at the beginning, it is more effective to form a low-temperature film by combining the two by chemical bonds. However, it was possible to improve the low-temperature film-forming property by not forming a chemical bond between them.
Furthermore, the adhesion to a base material such as a polyester film is also improved by such a technique, and even when applied to the in-line coating method, the formed coating layer has a much better followability to film deformation, and is heat resistant. The present invention has been completed by finding out that it has excellent properties, water resistance, solvent resistance, transparency and the like.

  That is, in the present invention, resin particles containing a water-dispersible polyurethane resin (A) and a hydrophobic polyester polyol (B-1) and / or a hydrophobic polyether polyol (B-2) are dispersed in water. The aqueous dispersion (C) comprises a crosslinking agent (D) capable of reacting with a hydroxyl group, and the water-dispersible polyurethane resin (A) condenses a dicarboxylic acid mainly composed of an aromatic dicarboxylic acid and a polyol. The polyester polyol (a-1) and polyisocyanate obtained in the above are reacted as essential components and contain 15 to 35% by weight of an aromatic cyclic structure. The hydrophobic polyester polyol (B-1 ) And / or hydrophobic polyether polyol (B-2) is liquid at normal temperature and contains 20 to 50% by weight of an aromatic cyclic structure. There is provided a packaging material.

The technical term “hydrophobic” is generally understood to mean that a substance has a property of weak interaction with water and weak affinity with water. “Hydrophobic” means that a substance alone does not disperse or dissolve in water.
Further, in the present specification, the term “liquid at normal temperature” means a liquid state at 25 ° C.

  Since the water-based coating agent of the present invention is excellent in film forming properties at low temperatures, it has processability in a wide range of temperatures, and excellent adhesion to plastic films, and further has blocking resistance, water resistance, solvent resistance, Because of its excellent transparency, it is suitable as a coating agent used in in-line coating methods and off-line coating methods for plastic films. As a primer coating agent or anchor coating agent, food packaging films, decoration materials, metal deposition It can be used in a wide range of applications such as film, paints, inks, surface treatment agents for fibers and leather.

The best mode for carrying out the invention will be described in detail below.
The aqueous coating agent of the present invention is
Water dispersion (C) in which resin particles containing water-dispersible polyurethane resin (A) and hydrophobic polyester polyol (B-1) and / or hydrophobic polyether polyol (B-2) are dispersed in water And a cross-linking agent (D) capable of reacting with a hydroxyl group.

  A chemical bond is substantially formed between the water-dispersible polyurethane resin (A) contained in the resin particles and the hydrophobic polyester polyol (B-1) or the hydrophobic polyether polyol (B-2). It is preferable not to allow the water-dispersible polyurethane resin (A) to be effectively plasticized and to further enhance the effect of excellent film-forming properties at low temperatures produced by the present invention.

Next, the water dispersible polyurethane resin (A) having an aromatic cyclic structure used in the present invention will be described.
The water dispersible polyurethane resin (A) used in the present invention has an aromatic cyclic structure, and has a carboxyl group or a sulfonic acid group or a salt thereof as a hydrophilic group for imparting water dispersibility. Those having a representative anionic group in the molecule are preferred.

  Such water-dispersible polyurethane resin (A) uses polyester polyol (a-1) obtained by condensing a dicarboxylic acid mainly composed of an aromatic dicarboxylic acid and a polyol and a polyisocyanate as essential components. Can be obtained by reacting by a conventionally known method using other polyols or polyamines as chain extenders. In addition, as will be described in detail later, at least one of these polyester polyols (a-1), other polyols, and polyamines can be obtained by using a water-dispersible polyurethane resin (A ) Can be introduced with an anionic group.

  The content of the anionic group contained in the water-dispersible polyurethane resin (A) has a strong correlation with the particle diameter when the water-dispersible polyurethane resin (A) is made into an aqueous dispersion. It is preferable to prepare such that the group content is in the range of 50 to 1000 mmol / kg with respect to the water-dispersible polyurethane resin (A). Within such a range, it is possible to obtain good dispersion stability of the resin particles, in which the dispersed resin particles are stable without aggregation or precipitation even during long-term storage without impairing water resistance.

As a method for introducing an anionic group into the water-dispersible polyurethane resin (A), a known method can be employed.
For example, (i) a polyol having a polyol containing an anionic group represented by a carboxyl group or a sulfonic acid group or a salt thereof as an essential component (in this case, a polyol containing an anionic group is a polyester polyol (a-1 And any other polyol used if necessary.) And a method of producing a water-dispersible polyurethane resin (A) having an anionic group by reacting with a polyisocyanate,

(ii) In the above (i), a prepolymer containing an isocyanate group by reacting the polyol and the polyisocyanate under the condition that the isocyanate group of the polyisocyanate is excessive with respect to the hydroxyl group of the polyol. A method for producing a water-dispersible polyurethane resin (A) having an anionic group by producing and further chain-extending (high molecular weight) by reacting with a low molecular weight polyol or polyamine,

(iii) Use of a polyol having no anionic group (polyester polyol (a-1) and, if necessary, other polyol), and the condition that the isocyanate group of the polyisocyanate is excessive with respect to the hydroxyl group of the polyol. To produce a prepolymer containing an isocyanate group by reacting the polyol with the polyisocyanate, and reacting a low molecular weight polyol or polyamine having an anionic group to cause chain elongation (high molecular weight). A method for producing a water-dispersible polyurethane resin (A) having the following can be adopted.

  Moreover, when water-dispersible polyurethane resin (A) has a carboxyl group and / or a sulfonic acid group as an anionic group, it can provide favorable water dispersibility by neutralizing a part or all of them. it can. At that time, for example, at least one selected from the group consisting of organic amines such as ammonia, triethylamine, pyridine, morpholine, alkanolamines such as monoethanolamine, and metal base compounds containing Na, K, Li, Ca, etc. A summing agent can be used. The neutralization rate is preferably neutralizer / anionic group = 0.5 to 3.0 (molar ratio), more preferably neutralizer / anionic group = 0.9 to 2.0 (molar ratio). It is desirable to use in the range. If it is this range, the stable water dispersibility can be provided, without impairing water resistance.

  In the above method (i) or (ii), as a typical polyol containing a carboxyl group that can be used as a polyol containing an anionic group, 2,2′-dimethylolpropionic acid, 2,2′-dimethylolbutanoic acid, 2,2′-dimethylolbutyric acid, 2,2′-dimethylolvaleric acid and the like can be mentioned. Also, carboxyl group-containing polyester polyols obtained by reacting these carboxyl group-containing polyols and various polycarboxylic acids can be used.

  In the method (i) or (ii), typical examples of polyols containing sulfonic acid groups that can be used as polyols containing anionic groups include 5-sulfoisophthalic acid, sulfo Dicarboxylic acids such as terephthalic acid, 4-sulfophthalic acid, and 5 [4-sulfophenoxy] isophthalic acid, or at least one selected from the group consisting of metal ions such as Na, K, Li, and Ca, ammonia, diethylamine, and triethylamine And polyester polyols containing aromatic sulfonic acid groups obtained by reacting various sulfonates with various polyols or salts thereof.

  In addition to the polyol containing the anionic group, the ethylene oxide repeating unit is contained at least 30% by weight, and the number average molecular weight containing at least one active hydrogen atom-containing group is 300 to 10,000. Nonionic group-containing polyols such as polyalkylene glycol can be used in combination. As nonionic group content, it is preferable to prepare so that it may become 10 weight% or less of the whole water-dispersible polyurethane resin (A). Within such a range, good water dispersion stability can be obtained without impairing water resistance.

  Next, a polyester polyol (a-1) obtained by condensing a dicarboxylic acid mainly composed of the above-mentioned aromatic dicarboxylic acid and a polyol, which is used when the water-dispersible polyurethane resin (A) is produced, will be described. . Such polyester polyol (a-1) can be produced by a known method using various known dicarboxylic acids and various polyols.

  Examples of the aromatic dicarboxylic acid that can be used for producing the polyester polyol (a-1) include terephthalic acid, isophthalic acid, orthophthalic acid, 1,4-naphthalenedicarboxylic acid, and 2,5-naphthalenedicarboxylic acid. Aromatic dicarboxylic acids such as acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bis (phenoxy) ethane-P, P'-dicarboxylic acid, and their acid anhydrides or ester-forming properties Derivatives, aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid and their ester-forming derivatives, sulfonic acid group-containing aromatic dicarboxylic acids such as 5-sulfoisophthalic acid and their ester-forming derivatives.

  In addition to the aromatic dicarboxylic acid, an aliphatic carboxylic acid or an alicyclic carboxylic acid can be used in combination. For example, aliphatic dicarboxylic acids such as succinic acid, succinic anhydride, adipic acid, suberic acid, azelaic acid, sebacic acid, dimer acid, maleic anhydride and fumaric acid, and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid And anhydrides or ester-forming derivatives thereof. These may be used alone or in combination of two or more.

  Moreover, as a polyol which can be used when manufacturing the said polyester polyol (a-1), aromatic cyclic structures, such as bisphenol A, bisphenol S, hydroquinone, bishydroxyethoxybenzene, or these, and an alkylene oxide adduct, for example. A polyol having

Ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol Aliphatic diols such as tetraethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl 1,3-propanediol; Cyclohexanediol, 1,4-cyclohexanedimethanol, hydrogenated bisphenol A and other alicyclic diols; and polyfunctional components such as glycerin, trimethylolpropane and pentaerythritol polyols.
In addition, an aliphatic polyol obtained by ring-opening polymerization of a cyclic ester such as ε-caprolactone or γ-valerolactone in the presence of the polyol and the catalyst can also be used.
These may be used alone or in combination of two or more.

  The polyester polyol (a-1) preferably has a hydroxyl value in the range of 10 to 350, and particularly preferably in the range of 20 to 300. When the hydroxyl value is in such a range, the resulting polyurethane resin has high cohesive force, and the solvent resistance, water resistance and blocking resistance when used in an aqueous coating agent are improved.

  In order to produce the water-dispersible polyurethane resin (A) used in the present invention, the polyester polyol (a-1) was obtained by condensing a dicarboxylic acid mainly composed of an aromatic dicarboxylic acid and a polyol. It is preferable to use a polyester polyol in which 70 to 100 mol% of the total amount of the dicarboxylic acid is terephthalic acid and / or isophthalic acid. By using such a polyester polyol, an aqueous coating that can form a coating layer having excellent adhesion to a substrate, particularly a polyester film, and excellent heat resistance such as blocking resistance, water resistance, solvent resistance, and transparency. An agent can be provided.

  When the water-dispersible polyurethane resin (A) used in the present invention is produced, polyols other than the above-described polyester polyol (a-1) are also used within a range that does not impair substrate adhesion and blocking resistance. be able to.

  Examples of such polyols include polyester polyols, polyether polyols, polycarbonate polyols, and the like. These may be used alone or in combination of two or more. In particular, it is preferable to use polyester polyol as a main component from the viewpoint of excellent adhesion to a wide range of substrates and cost.

The said polyester polyol makes aliphatic carboxylic acid and alicyclic carboxylic acid and various polyols react by a well-known method illustrated as what can be used when manufacturing the above-mentioned polyester polyol (a-1). Can be manufactured.
At this time, monoalcohols such as methanol, ethanol, n-butanol, isopropanol, and n-hexanol may be used in combination as long as the high molecular weight of the water-dispersible polyurethane resin (A) is not inhibited.

  As described above, in producing the water-dispersible polyurethane resin (A), the polyester polyol (a-1) and, if necessary, other polyols and various polyisocyanates in advance with respect to the hydroxyl groups of all polyols, A prepolymer containing an isocyanate group is prepared in advance by reacting under conditions where the isocyanate group of the polyisocyanate is excessive, and then a low molecular weight polyol or polyamine is reacted with this to extend the chain to increase the molecular weight. You can also

  In this case, as the low molecular weight polyol, carboxyl groups such as 2,2′-dimethylolpropionic acid, 2,2′-dimethylolbutanoic acid, 2,2′-dimethylolbutyric acid, 2,2′-dimethylolvaleric acid and the like are used. Containing polyols;

Ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol Aliphatic diols such as tetraethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl 1,3-propanediol, 1,4- Cyclohexanediol, 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, and other alicyclic diols can be used, and polyols such as glycerin, trimethylolpropane, and pentaerythritol are used as polyfunctional components. It can also be used in combination.

  Examples of the polyamine include diaminosulfonates such as metal salts of N- (2-sulfoethyl) ethylenediamine and 2- (β-aminoalkyl-aminopropionamide) -alkanesulfonates, and aliphatics such as ethylenediamine. A polyamine having an anionic group such as an adduct of a primary diamine and an α-olefinic carboxylic acid such as (meth) acrylic acid;

1,2-diaminoethane, 1,2- or 1,3-diaminopropane, 1,2- or 1,3- or 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, Piperazine, N, N′-bis- (2-aminoethyl) piperazine, 1-amino-3-aminomethyl-3,5,5-trimethyl-cyclohexane (isophoronediamine), bis- (4-aminocyclohexyl) methane, Diamines such as bis- (4-amino-3-butylcyclohexyl) methane, 1,2-, 1,3- or 1,4-diaminocyclohexane or 1,3-diaminopropane, polyamines such as diethylenetriamine and triethylenetetramine Furthermore, polyamides having no anionic group such as hydrazine or hydrazine derivatives such as adipic acid dihydrazide It can be used.

  Furthermore, amino alcohol having both an amino group and an alcoholic hydroxyl group in the molecule can also be used. For example, ethanolamine, N-methyldiethanolamine, propanolamine, N-methyldiisopropanolamine, N-ethyldiethyleneamine, N-ethyldiisopropanolamine, aminoethylethanolamine, diethanolamine and the like can also be used.

As the polyamine, it is preferable to use a polyamine having two or more functional groups in order not to impair durability. In this case, a polyamine having two or more functional groups may be used alone, or two or more kinds may be used. It may be used in combination with an average functional group number of 2 or more.
When chain-extending the prepolymer containing an isocyanate group to increase the molecular weight, the polyamine is preferably used in an amount of 1.9 equivalent ratio or less, more preferably 0.6- The range is 1.0 equivalent ratio. If chain extension is performed using polyamine within such a range, the resulting aqueous coating agent can have excellent durability and light resistance.

As the polyisocyanate used for producing the water-dispersible polyurethane resin (A) used in the present invention, known ones can be used.
For example, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, cyclohexane-1,3- or 1,4-diisocyanate, 1-isocyanato-3-isocyanatomethyl-3 , 5,5-trimethylcyclohexane (also known as isophorone diisocyanate; IPDI), dicyclohexylmethane-4,4′-diisocyanate (also known as hydrogenated MDI), 2- or 4-isocyanatocyclohexyl-2′-isocyanatocyclohexylmethane, 3- or 1,4-bis- (isocyanatomethyl) -cyclohexane, bis- (4-isocyanato-3-methylcyclohexyl) methane, 1,3- or 1,4-α, α, α'α'-tetra Methyl xylylene diisocyanate 2,4- or 2,6-diisocyanatotoluene, 2,2'-, 2,4'- or 4,4'-diisocyanatodiphenylmethane (MDI), 1,5-naphthalene diisocyanate, p- or m-phenylene diisocyanate, xylylene diisocyanate, diphenyl-4,4′-diisocyanate and the like can be used.

  Among these, the use of aromatic diisocyanate is desirable particularly when considering the mechanical strength and the like, and when considering the durability and light resistance, the aliphatic or cycloaliphatic diisocyanate compound is particularly desirable. Use is desirable.

As an organic solvent used when manufacturing the water-dispersible polyurethane resin (A), fine particles are formed during water dispersion, and the residual solvent contained in the water dispersion (C) after solvent removal is removed. In consideration, it is preferable to use an organic solvent having a boiling point of 150 ° C. or lower.
Examples of the organic solvent having a boiling point of 150 ° C. or lower include benzene, toluene, ethyl acetate, acetone, methyl ethyl ketone, diethyl ether, tetrahydrofuran, methyl acetate, acetonitrile, chloroform, and methylene chloride. These can be used alone or in combination. Among these, it is particularly preferable to use acetone, methyl ethyl ketone, or ethyl acetate as a solvent having high solubility for the water-dispersible polyurethane resin (A). Further, for the purpose of enhancing water dispersibility, alcohol solvents such as methanol, ethanol, isopropyl alcohol and the like may be used at the time of water dispersion as long as the high molecular weight of the polyurethane resin is not inhibited.

The content of urethane bond units (—NH—COO—) per 1000 g of the water dispersible polyurethane resin (A) is preferably in the range of 1.0 to 4.0 mol.
Further, as described above, when the prepolymer is chain-extended by reacting with a polyamine, a urea bond is formed. In this case, urethane bond units (1000 g) of the water-dispersible polyurethane resin (A) ( The total content of —NH—COO— and urea bond units (—NH—CO—NH—) is preferably in the range of 1.0 to 4.0 mol.
If it is this range, since the cohesive force of a polyurethane molecule will become high, the hardness of the coating layer obtained will become suitable, and heat resistance, such as solvent resistance and blocking resistance, can be improved.

  The content of the aromatic cyclic structural unit in the water-dispersible polyurethane resin (A) is preferably in the range of 15 to 35% by weight, and more preferably in the range of 20 to 30% by weight. If it is this range, the aqueous coating agent obtained will become the thing excellent in heat resistance, such as especially the adhesiveness with respect to a polyester base material, solvent resistance, water resistance, and blocking resistance.

  Further, the number average molecular weight of the water dispersible polyurethane resin (A) is preferably in the range of 5000 to 50000, and more preferably in the range of 6000 to 30000. If it is this range, the aqueous coating agent obtained will be excellent in heat resistance, such as solvent resistance, water resistance, and blocking resistance.

Next, the hydrophobic polyester polyol (B-1) and the hydrophobic polyether polyol (B-2) which are liquid at room temperature and contain 20 to 50% by weight of the aromatic cyclic structural unit used in the present invention. explain.
In the present specification, the term “hydrophobic polyol (B)” means both the hydrophobic polyester polyol (B-1) and the hydrophobic polyether polyol (B-2).

  Since the hydrophobic polyol (B) is liquid at room temperature, it acts as a film-forming aid, promotes plasticization of the water-dispersible polyurethane resin (A), and improves the film-forming property. In order to enhance this effect, it is preferable that the hydrophobic polyol (B) is not substantially chemically bonded to the water-dispersible polyurethane resin (A).

  The hydrophobic polyol (B) is not water-dispersible by itself, but is taken into dispersed particles formed from the water-dispersible polyurethane resin (A) that exists stably in water. It exists in the form of being wrapped in a layer of a dispersible polyurethane resin. By taking this form, it is presumed that even if the amount of the hydrophobic polyol (B) used is reduced, a suitable low-temperature film-forming property improving effect can be obtained.

The content of the hydrophilic group in which the hydrophobic polyol (B) can be hydrophobic is (1) in the case of an ionic group, 50 mmol / kg or less, and (2) an ethylene oxide [[CH ₂ CH ₂ O) n; n ≧ 5] In the case of a structural unit, it is preferable that both conditions of 5% by weight or less are satisfied. By using such a hydrophobic polyol (B), the resulting coating layer has excellent water resistance.

The hydrophobic polyester polyol (B-1) used in the present invention can be produced by a known method using various known dicarboxylic acids and various polyols, and either of the dicarboxylic acid and the polyol is aromatic. It is necessary to use one having a group cyclic structure.
Aromatic dicarboxylic acids that can be used in producing such hydrophobic polyester polyol (B-1), and aliphatic carboxylic acids and alicyclic carboxylic acids that can be used in combination with them, and aromatic cyclic structures. Examples of the polyol and the aliphatic polyol or alicyclic polyol that can be used in combination with the polyol are those used when producing the polyester polyol (a-1) that is a raw material of the water-dispersible polyurethane resin (A). Each can be used.

  Among them, as the hydrophobic polyester polyol (B-1), at least one polycarboxylic acid selected from isophthalic acid and orthophthalic acid is used as the dicarboxylic acid used in an amount of 60 mol% or more of the total dicarboxylic acid. The polyol is preferably an aliphatic having 2 to 8 carbon atoms.

  More preferably, as the dicarboxylic acid, at least 60 mol% of the total amount of the dicarboxylic acid is orthophthalic acid. By using such a dicarboxylic acid, the resulting hydrophobic polyester polyol (B-1) has low crystallinity and is a liquid suitable for the present invention.

  More preferably, at least one polyol selected from the group consisting of ethylene glycol, diethylene glycol and triethylene glycol is 50 mol% or more of the total polyol.

  Within such a range, the obtained hydrophobic polyester polyol (B-1) has a low crystal orientation and becomes liquid at room temperature, and can plasticize the water-dispersible polyurethane resin (A) more effectively. Since it is possible to improve the low-temperature film-forming property, it forms an extremely uniform coating layer when applied to an off-line coating method in which drying is performed at a relatively low temperature of 100 ° C. or lower, and even when drying at room temperature. It becomes possible to do.

  The hydrophobic polyether polyol (B-2) is produced by adding a cyclic ether compound such as alkylene oxide or a cyclic carbonate compound to a polyol having various aromatic cyclic structures by a ring-opening polymerization reaction in the presence of a catalyst. can do. In particular, a cyclic compound adduct of a polynuclear phenol compound obtained by reacting a polynuclear phenol compound with the following cyclic compound such as alkylene oxide in the presence of a catalyst is more preferable, and in particular, propylene oxide addition of the polynuclear phenol compound. The product is particularly preferred.

  Examples of the polynuclear phenol compounds include bisphenol A, bisphenol S, bisphenol F, bisphenol E, bisphenol Z, tetramethylbisphenol A, diallyl bisphenol A, 4-4′-oxybisphenol, biphenol, tetramethylbiphenol, bisphenol fluorene, bis Bisphenol compounds such as cresol fluorene and terpene diphenol, phenol novolak, cresol novolak, xylylene novolak, bisphenol A novolak, triphenylmethane novolak, biphenyl novolak, dicyclopentadienephenol novolak, terpene phenol novolak and other novolak You can select and use.

  Examples of the cyclic compound include cyclic ether compounds such as ethylene oxide, propylene oxide, butylene oxide, oxetane and tetrahydrofuran, and other cyclic carbonate compounds such as ethylene carbonate and propylene carbonate, which can be appropriately selected and used.

  Among these, as the hydrophobic polyether polyol (B-2), a propylene oxide adduct of a bisphenol compound and a propylene oxide adduct of a phenol novolac compound containing a structural unit derived from propylene oxide are liquid at room temperature. It is preferable. Such a hydrophobic polyether polyol has a greater plasticizing effect on the water-dispersible polyurethane resin (A), thereby improving the low-temperature film-forming property. Even when applied and dried under relatively low temperature conditions, A uniform coating layer can be formed.

  In this case, from the viewpoint of compatibility with the water-dispersible polyurethane resin (A), those obtained by adding 2 to 60 mol of propylene oxide to 1 mol of the polyol having the aromatic cyclic structure are preferable. Furthermore, what added 2.5-30 mol propylene oxide with respect to 1 mol of polyol which has an aromatic cyclic structure is more preferable.

  The hydrophobic polyol (B) preferably has a number average molecular weight in the range of 200 to 4000, and more preferably has a number average molecular weight in the range of 250 to 2000. Within such a range, the viscosity at normal temperature of the hydrophobic polyol (B) becomes low, and the plasticizing effect on the water-dispersible polyurethane resin (A) becomes larger, so that the low-temperature film-forming property can be improved. .

  Moreover, it is preferable that the hydroxyl value which the said hydrophobic polyol (B) has is in the range of 20-500, More preferably, it exists in the range of 50-400. When the hydroxyl value and the number average molecular weight of the hydrophobic polyol (B) are within the above ranges, the reactivity with the crosslinking agent (D) capable of reacting with the hydroxyl group is suitable, and crosslinking is performed without inhibiting the low-temperature film-forming property. In the in-line coating method that is processed at a high temperature, since the reaction proceeds, even if coating is performed in the middle of the film stretching process, the film is further continuously tracked in the stretching process, and has excellent followability to film deformation and cracks (cracks) ) And the like are not generated, and a tough coating layer can be formed after completion of the crosslinking reaction, and heat resistance such as solvent resistance, water resistance and blocking resistance can be improved.

  The hydrophobic polyester polyol (B-1) and the hydrophobic polyether polyol (B-2) may be used alone or in combination. Among these, the hydrophobic polyester polyol (B-1) is preferable in consideration of the adhesion to the polyester base material and the blocking resistance.

The content of the aromatic cyclic structural unit in the hydrophobic polyol (B) is preferably in the range of 20 to 50% by weight, and more preferably in the range of 25 to 40% by weight.
If it is this range, the coating film obtained after bridge | crosslinking will be excellent in heat resistance, such as especially the adhesiveness with respect to a polyester base material, solvent resistance, water resistance, and blocking resistance.

Next, a method for producing an aqueous dispersion (C) in which resin particles containing the water-dispersible polyurethane resin (A) and the hydrophobic polyol (B) used in the present invention are dispersed in water will be described. .
Such an aqueous dispersion (C) can be produced by combining various known methods such as the method shown in (i) or (ii) below.

(I) The water-dispersible polyurethane resin (A) and the hydrophobic polyol (B) are uniformly mixed, then neutralized, water is added to the mixture, emulsified and dispersed, and the solvent is removed as necessary. Thus, an aqueous dispersion (C) can be obtained.

(Ii) In an organic solvent that does not contain an active hydrogen atom-containing group in the molecule, preferably under conditions of 30 to 150 ° C., more preferably 50 to 120 ° C., polyester polyol (a-1) and other The equivalent ratio of the isocyanate group to the hydroxyl group of the polyol and polyisocyanate is preferably in the range of isocyanate group / hydroxyl group = (1-3) / 1, more preferably (1-2) / 1. By the method, a prepolymer in which isocyanate groups remain is produced.
At this time, a prepolymer having an anionic group can be obtained by using a polyol having a carboxyl group or a sulfonic acid group as the polyol. In this case, the polyol having a carboxyl group or a sulfonic acid group may be any of polyester polyol (a-1) and other polyols used if necessary.
The obtained prepolymer and the hydrophobic polyol (B) are mixed and melted uniformly. At this time, it is important to keep the temperature at 60 ° C. or less so that the isocyanate group of the prepolymer does not react with the hydroxyl group of the hydrophobic polyol (B).

  Next, after neutralizing the mixture, water is added dropwise or dividedly into the mixture to emulsify and disperse. At this time, it is important to carry out emulsification at 60 ° C. or lower in order to suppress side reactions with water.

  Next, an aqueous solution containing a low molecular weight polyol or polyamine is added to the obtained aqueous dispersion in which the isocyanate groups remain to cause chain elongation (high molecular weight), whereby the intended aqueous dispersion (C) is obtained. Further, the aqueous dispersion (C) with less harmfulness can be obtained by removing the solvent of the obtained aqueous dispersion as necessary.

  The mixing ratio of the water-dispersible polyurethane resin (A) and the hydrophobic polyol (B) used in the present invention is preferably (A) / (B) = 95/5 to 50/50 by weight ratio, 90/10 to 70/30 is particularly preferable. Within such a range, stable particle formation can be achieved without impairing water dispersibility. Furthermore, since the water-dispersible polyurethane resin (A) is appropriately plasticized by the hydrophobic polyol (B), the low-temperature film-forming property and substrate followability of the resulting aqueous coating agent are excellent. Even if it applies to any of the method and the off-line coating method, it becomes possible to form a good coating layer without causing a coating film defect.

Next, the crosslinking agent (D) that can react with a hydroxyl group used in the present invention will be described.
The said crosslinking agent (D) is used in order to improve heat resistance, such as blocking resistance, wet heat resistance, and solvent resistance of the coating layer formed using the aqueous coating agent of this invention. As such a crosslinking agent (D), an amino resin, polyisocyanate, etc. can be used, for example. As said polyisocyanate, what has hydrophilic groups, such as polyoxyethylene and a carboxyl group, in a molecule | numerator, and what has water solubility or water dispersibility is preferable.

  When these crosslinking agents (D) are mixed with the aqueous dispersion (C) used in the present invention, the hydrophobic polyester polyol (B-1) or the water-dispersible polyurethane resin (A) in some cases over time at room temperature. And the crosslinking agent (D) itself self-condensates, it is not preferable to mix with the aqueous dispersion (C) and store for a long time. Therefore, although the pot life varies depending on the type of the crosslinking agent (D) used, the crosslinking agent (D) and the aqueous dispersion (C) are mixed by a known method immediately before application to the substrate, and the aqueous solution of the present invention. It is preferable to prepare a coating agent. In particular, when a polyisocyanate is used as the crosslinking agent (D), it is desirable to use it as soon as possible after mixing with the aqueous dispersion (C).

  The addition amount of the crosslinking agent (D) is preferably 1 to 20% by weight, more preferably 3 to 10% by weight based on the water-dispersible polyurethane resin (A) and the hydrophobic polyol (B) of the present invention. Is more preferable. Within such a range, it becomes possible to improve the heat resistance such as blocking resistance, the heat and humidity resistance, and the solvent resistance of the coating layer to be formed without impairing the adhesion and followability to the substrate.

  In addition, two or more kinds of the crosslinking agents (D) can be used in combination, and further a curing accelerator can be used. Moreover, crosslinking agents, such as an epoxy compound, a carbodiimide, an aziridine compound, and an oxazoline compound, can also be used together.

  The aqueous coating agent of the present invention can contain an aqueous acrylic resin, an aqueous polyester resin, an SBR latex resin, and the like as long as the base material adhesion and the low-temperature film-forming property are not impaired. These resins are preferably 30% or less, and particularly preferably 10% or less in terms of solid content in the coating agent.

  The aqueous coating agent of the present invention further includes inorganic fine particles (colloidal silica) for improving blocking resistance or slip resistance as required, alcohols such as ethanol and isopropyl alcohol for improving wettability, Anionic, nonionic hydrocarbon or fluorosurfactant, acetylene glycol leveling agent “Surfinol” (Air Products), or BYK-348, 346, 345, 341 (BYK-Chemie GmbH) The polyalkylene glycol-modified polysiloxane represented by (1) can be contained. Among these, an acetylene glycol leveling agent is preferable in order to improve wettability. Moreover, auxiliary agents, such as an antistatic agent, can also be mix | blended.

After adjusting the aqueous coating agent of the present invention to an arbitrary resin concentration, the base material is coated with a conventionally known coating method such as a gravure coating method, a rod coating method, a spray coating method, an air knife coating method, or a roll coating method. Can be applied on top.
At this time, the concentration of the resin is preferably adjusted to 0.1 to 40% by weight.
The thickness of the coating layer at this time is preferably in the range of 0.01 to 100 μm, and preferably in the range of 0.05 to 50 μm. Within this range, the substrate surface can be modified without impairing the characteristics of the substrate.

The aqueous coating agent of the present invention is excellent in adhesion to textile products, synthetic leather, artificial leather, natural leather, metal (aluminum, iron, copper), rubber, glass, paper, wood, etc., and its dry film is water resistant. Since it is also excellent in blocking resistance, it can be used in the fields of fibers and leather base materials, aqueous coating agents and the like, and is extremely useful.
Furthermore, the aqueous coating agent of the present invention can exhibit the above-mentioned performances even when applied to plastic. As the plastic, a plastic film that has been biaxially stretched in advance can be used as the plastic film, but in order to further enhance the effects of the present invention, during the biaxial stretching process of the plastic film, that is, before the biaxial stretching process is completed. Most preferably, it is applied to.

  Suitable plastics for applying the aqueous coating agent of the present invention include, for example, vinyl chloride resin, vinylidene chloride resin, polyamide resin (nylon), polyolefin resin (polyethylene resin, polypropylene resin), polyester resin, unsaturated polyester resin. , Polyurethane resin, polystyrene resin, acrylic resin, ethylene / vinyl acetate copolymer, polyvinyl alcohol polymer, ethylene / vinyl alcohol copolymer, and the like, and polyester resin and polyamide resin are particularly preferable.

  Examples of the polyester resin include films, sheets, and moldings such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, which are mainly composed of polyalkylene terephthalate, and other aromatic dicarboxylic acids such as isophthalic acid. , 2,6-naphthalenedicarboxylic acid or the like, or a mixture thereof, such as a film, sheet, or molded product.

  Examples of the polyamide-based resin include nylon 6 (polycoupleramide), nylon 66 (polyhexamethylene adipamide), nylon 610 (polyhexamethylene sebacamide), nylon 11 (polyundecanamide), and nylon 12 (polylauramide). Also included are films, sheets, moldings, etc. of metaxylylenediamine-based nylon and copolymers, modified products, and mixtures thereof.

  The aqueous coating agent of the present invention can be suitably used as a surface modifier for plastic films, but is particularly preferably used as a primer coating agent or an anchor coating agent for the purpose of improving easy adhesion of the plastic film surface. .

  The aqueous coating agent of the present invention can be an effective aqueous primer coating agent and aqueous anchor coating agent even for plastics that have not been surface-treated. It is preferable to use those subjected to physical and chemical treatment such as corona treatment and alkali treatment.

  The water-based coating agent of the present invention has processability at a wide range of temperatures, high substrate adhesion, and is excellent in blocking resistance, water resistance, solvent resistance, etc., so that it is not only in-line processing but also offline processing. And can be used in a wide range of applications such as light food packaging films, gas barrier films, and metal vapor deposition films.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these Examples. In the following, “part” and “%” are all based on weight unless otherwise specified. In addition, about the evaluation method of various characteristics, it is as follows.

[Adjustment of aqueous coating agents A and B]
In an aqueous solution obtained by diluting 100 parts of the aqueous dispersion obtained in Examples and Comparative Examples described later with 100 parts of water, Isocyanate of Aquanate 100 (manufactured by Nippon Polyurethane Industry Co., Ltd., having a polyethylene glycol side chain) A mixture obtained by adding 2 parts of a nurate body and sufficiently stirred so as to be uniformly dispersed was designated as an aqueous coating agent A.
Moreover, 5 parts of becamine APM (Dainippon Ink Chemical Co., Ltd. trimethylol melamine resin) was added to an aqueous solution obtained by diluting 100 parts of the aqueous dispersion obtained in Examples and Comparative Examples with 100 parts of water. An aqueous coating agent B was sufficiently stirred so as to uniformly disperse the product.

[Evaluation method of film-forming property]
1 g of the aqueous coating agent B prepared as described above was sampled on a metal petri dish having a diameter of 65 mm, and then uniformly diluted by adding 4 g of water. A film was prepared by drying for 24 hours, and the surface state of the obtained film was visually observed and represented by the following three-step evaluation.
○: A uniform film was formed.
Δ: A film was formed but a crack occurred in the film.
X: Powdered without forming a film.

[Creation of coating film]
On the base film (PET; 12 μm, OPP; 15 μm), the aqueous coating agent adjusted as described above is applied so that the film thickness upon drying is about 0.3 μm, and heat treatment and curing are performed under the following conditions. To obtain a surface-treated film.
Aqueous coating agent A; heat-treated at 80 ° C. for 60 seconds, and then cured at 23 ° C. and relative humidity of 65% for 2 days.
Aqueous coating agent B; heat-treated at 150 ° C. for 5 minutes, and then cured at 23 ° C. and relative humidity of 65% for 2 days.

[Adhesion to substrate <Cellophane adhesive tape peeling test>]
The surface treatment film (PET, OPP) obtained above was subjected to a peel test using a 24 mm width adhesive tape manufactured by Nichiban Co., Ltd., and the results were evaluated in five stages.
1: The adhesion is very weak and completely peels off.
2. Peel 50% or more.
3 ... 10-50% peeling.
4 ... Adhesive strength is quite strong and peels off less than 10%.
5 ... The adhesion is very strong and does not peel at all.

[Substrate following test]
The surface-treated OPP film obtained using the aqueous coating agent B was manually stretched at room temperature to observe the surface state of the coating layer, and the results were evaluated in three stages.
○ ... No cracks occur.
Δ: Slight cracking but no peeling of coating layer.
X: Cracks are generated, and the coating layer is completely peeled off from the film.

[Blocking resistance]
The treated surfaces of the surface-treated film obtained using the water-based coating agent B are bonded together and left to stand in an atmosphere of 40 ° C. and 65% RH under a load of 100 g / cm ² for 24 hours. The tackiness when peeled was evaluated in the following three stages.
○ ・ ・ ・ No stickiness, can be peeled off without any △ △ ・ ・ ・ Some stickiness but no change on the coated surface × ・ ・ ・ Surface defects due to adhesive have occurred on any coated surface

[Solvent resistance]
The coating layer of the surface-treated PET film obtained using the aqueous coating agent B is rubbed with a cotton swab soaked in ethyl acetate, and the number of times the coating layer is rubbed until the base material layer appears after dropping off, Five grades were evaluated.
1 ... less than 10 times 2 ... 10 times or more and less than 20 times 3 ... 20 times or more and less than 30 times 4 ... 30 times or more and less than 40 times
5 ... 50 times or more

〔water resistant〕
The surface-treated PET film obtained using the aqueous coating agent B was immersed in warm water at 40 ° C. for 24 hours, and then a peel test using a cellophane adhesive tape was performed.

[Adhesion to ink]
On the surface-treated PET film obtained using the aqueous coating agent B, a gravure ink prepared with the following composition was applied with a bar coater so that the film thickness upon drying was about 10 μm, and dried at 80 ° C. Further, after aging at 60 ° C. for 1 day, the results of a peel test using a cellophane adhesive tape were evaluated in five stages.
1: The adhesion is very weak and completely peels off.
2. Peel 50% or more.
3 ... 10-50% peeling.
4 ... Adhesive strength is quite strong and peels off less than 10%.
5 ... The adhesion is very strong and does not peel at all.
Gravure ink used for evaluation “CLS-709 white” (Draw Nippon Ink Chemical Co., Ltd. cellophane printing gravure ink); 50 parts from toluene / ethyl acetate / methyl ethyl ketone = 1/1/1 (weight ratio) Mixed solvent; 100 parts

<Preparation of polyester polyol for preparing water dispersible polyurethane resin (A)>
While introducing nitrogen gas in a reaction vessel equipped with a thermometer, a nitrogen gas inlet tube, and a stirrer, 830 parts of terephthalic acid, 830 parts of isophthalic acid, 374 parts of ethylene glycol, 598 parts of neopentyl glycol, and 0.5 parts of dibutyltin oxide The polyester polyol P-1 having a hydroxyl value of 74.5 and an acid value of 0.2 was obtained by carrying out a polycondensation reaction at 230 ° C. for 15 hours until the acid value became 1 or less at 180 to 230 ° C.
According to the composition shown in Table 1, polyester polyol P-3 was obtained in the same procedure as described above.
While introducing nitrogen gas in a reaction vessel equipped with a thermometer, a nitrogen gas introduction tube, and a stirrer, 664 parts of terephthalic acid, 631 parts of isophthalic acid, 472 parts of 1,4-butanediol, 447 parts of neopentyl glycol, and After 0.5 parts of dibutyltin oxide was charged and esterified at 180 to 230 ° C. for 5 hours, a polycondensation reaction was performed at 230 ° C. for 6 hours until the acid value became 1 or less. Next, the mixture was cooled to 120 ° C., 321 parts of adipic acid and 268 parts of 2,2′-dimethylolpropionic acid were added, the temperature was raised again to 170 ° C., and the reaction was carried out at this temperature for 20 hours. Polyester polyol P-2 containing a carboxyl group of .8 was obtained. (See Table 1)

<Preparation of hydrophobic polyester polyol>
While introducing nitrogen gas in a reaction vessel equipped with a thermometer, a nitrogen gas inlet tube, and a stirrer, 1660 parts of orthophthalic acid, 1637 parts of diethylene glycol and 0.5 parts of dibutyltin oxide were charged, and the acid value was 1 at 180 to 230 ° C. A polycondensation reaction was performed at 230 ° C. for 15 hours until the following was obtained, thereby obtaining polyester polyol Q-1 having an aromatic cyclic structure having a hydroxyl value of 190 and an acid value of 0.3.
According to the composition shown in Table 2, polyester polyols Q-3 and Q-4 and polyester polyol Q-2 having an aromatic cyclic structure were obtained in the same procedure as described above.

<Preparation of hydrophobic polyether polyol>
A liquid compound obtained by adding 2.8 mol of propylene oxide to 1 mol of bisphenol A was used as polyether polyol R. The polyether polyol R had a hydroxyl value of 282 and an aromatic cyclic structural unit content of 39.9%.

Example 1
1000 parts of polyester polyol P-1 was dehydrated at 100 ° C. under reduced pressure, and after cooling to 80 ° C., 907 parts of methyl ethyl ketone was added and sufficiently stirred to dissolve, and 80 parts of 2,2′-dimethylolpropionic acid was added, Next, 281 parts of isophorone diisocyanate was added and reacted at 75 ° C. for 8 hours to carry out a urethanization step.
After confirming that the isocyanate value was 0.1% or less, the mixture was cooled to 50 ° C., 340 parts of the polyester polyol Q-1 was added to make a homogeneous solution, and then neutralized by adding 60 parts of triethylamine. 7000 parts of water was added to make it water-soluble.
After removing methyl ethyl ketone from the obtained transparent reaction product under reduced pressure at 40 to 60 ° C., water was added to adjust the concentration to obtain a stable transparent colloidal aqueous dispersion having a nonvolatile content of 20%.
Using the obtained aqueous dispersion, aqueous coating agents A and B were prepared by the above-described method, and then various evaluations were performed. Adhesion to the substrate, substrate followability, blocking resistance, solvent resistance In addition, good physical properties were obtained in both water resistance and ink adhesion. <Table 3-1>

Example 2
As shown in Table 3-1, the same operation as in Example 1 was carried out except that 340 parts of polyether polyol H was used instead of polyester polyol Q-1 in Example 1, and stable transparency with a nonvolatile content of 20% was obtained. A colloidal aqueous dispersion was obtained.
Using the obtained aqueous dispersion, aqueous coating agents A and B were prepared by the above-described method, and then various evaluations were performed. As shown in Table 3-1, good physical properties were obtained. .

Example 3
After dehydrating 1000 parts of polyester polyol P-2 at 100 ° C. under reduced pressure, cooling to 80 ° C., adding 812 parts of methyl ethyl ketone, dissolving with sufficient stirring, adding 20 parts of 1,4-butanediol, and then dicyclohexylmethane-4 , 4′-diisocyanate (hydrogenated MDI) 198 parts was added and reacted at 75 ° C. for 8 hours.
After confirming that the isocyanate value became 0.1% or less, the mixture was cooled to 50 ° C., 135 parts of polyester polyol Q-1 was added, and neutralized by adding 84 parts of triethylamine, and then 7000 parts of water was added. In addition, it became water-soluble.
After removing methyl ethyl ketone from the obtained transparent reaction product under reduced pressure at 40 to 60 ° C., water was added to adjust the concentration to obtain a stable transparent colloidal aqueous dispersion having a nonvolatile content of 20%.
Using the obtained aqueous dispersion, aqueous coating agents A and B were prepared by the above-described method, and then various evaluations were performed. As shown in Table 3-1, good physical properties were obtained. .

Example 4
As shown in Table 3-1, the same operation as in Example 1 was performed except that 151 parts of polyester polyol Q-3 was used instead of polyester polyol Q-1 in Example 1, and a stable non-volatile content of 20% was obtained. A transparent colloidal aqueous dispersion was obtained.
Using the obtained aqueous dispersion, aqueous coating agents A and B were prepared by the above-described method, and then various evaluations were performed. As shown in Table 3-1, good physical properties were obtained. .

Example 5
As shown in Table 3-1, the same operation as in Example 1 was performed except that 583 parts of polyester polyol Q-3 was used instead of polyester polyol Q-1 in Example 1, and a stable non-volatile content of 20% was obtained. A transparent colloidal aqueous dispersion was obtained.
Using the obtained aqueous dispersion, aqueous coating agents A and B were prepared by the above-described method, and then various evaluations were performed. As shown in Table 3-1, good physical properties were obtained. .

Comparative Example 1
1000 parts of polyester polyol P-3 was dehydrated at 100 ° C. under reduced pressure, then cooled to 80 ° C., 897 parts of methyl ethyl ketone was added and dissolved with sufficient stirring, 80 parts of 2,2′-dimethylolpropionic acid was added, and then isophorone 244 parts of diisocyanate was added and reacted at 75 ° C. for 8 hours.
After confirming that the isocyanate value became 0.1% or less, the mixture was cooled to 50 ° C., 70 parts of polyester polyol Q-1 was added, 53 parts of triethylamine was added to neutralize, and 7000 parts of water was added. And became water-soluble.
After removing methyl ethyl ketone from the obtained transparent reaction product under reduced pressure at 40 to 60 ° C., water was added to adjust the concentration to obtain a stable transparent colloidal aqueous dispersion having a nonvolatile content of 20%.
Using the obtained aqueous dispersion, the aqueous coating agents A and B were prepared by the above-described method and then subjected to various evaluations. As shown in Table 3-2, the substrate adhesion, blocking resistance, Solvent resistance was not sufficient.

Comparative Example 2
As shown in Table 3-2, the same operation as in Example 1 was performed except that the polyester polyol Q-1 of Example 1 was not used, and a stable transparent colloidal aqueous dispersion having a nonvolatile content of 20% was obtained. .
Using the obtained aqueous dispersion, the aqueous coating agents A and B were prepared by the above-described method and then subjected to various evaluations. As shown in Table 3-2, the film forming property was low, the OPP adhesiveness, And base material followability was not enough.

Comparative Example 3
As shown in Table 3-2, the same operation as in Example 1 was performed except that polyester polyol Q-2 was used instead of polyester polyol Q-1 in Example 1, but polyurethane resin and polyester polyol Q- The compatibility with 2 was poor, and a stable aqueous dispersion could not be obtained.

Comparative Example 4
As shown in Table 3-2, a stable transparent colloid having a non-volatile content of 20% was carried out in the same manner as in Example 1 except that polyester polyol Q-4 was used instead of polyester polyol Q-1 in Example 1. A water dispersion was obtained.
Using the obtained aqueous dispersion, aqueous coating agents A and B were prepared by the above-described method, and then various evaluations were performed. As shown in Table 3-2, polyester polyol Q-4 was solid at room temperature. Therefore, the film forming property of the coating agent was low, and the adhesion to the OPP substrate and the substrate followability were not sufficient.

Comparative Example 5
After 800 parts of polyester polyol P-1 and 1200 parts of polyester polyol Q were dehydrated at 100 ° C. under reduced pressure, and then cooled to 80 ° C., 977 parts of methyl ethyl ketone was added and sufficiently stirred and dissolved, and then 2,2′-dimethylol. 80 parts of propionic acid was added, and then 385 parts of dicyclohexylmethane-4,4′-diisocyanate (hydrogenated MDI) was added and reacted at 75 ° C. for 8 hours.
After confirming that the isocyanate value became 0.1% or less, the mixture was cooled to 50 ° C., neutralized by adding 60 parts of triethylamine, and water-solubilized by adding 7000 parts of water. After removing methyl ethyl ketone from the obtained transparent reaction product under reduced pressure at 40 to 60 ° C., water was added to adjust the concentration to obtain a stable transparent colloidal aqueous dispersion having a nonvolatile content of 20%.
Using the obtained aqueous dispersion, aqueous coating agents A and B were prepared by the above-described method, and then various evaluations were performed. As shown in Table 3-2, plasticization with a hydrophobic polyol (B) was performed. Since there was no effect, the film-forming property and the substrate followability were not sufficient.

Note 1) Hydrogenated MDI; dicyclohexylmethane-4,4'-diisocyanate

Claims (7)

Water dispersion (C) in which resin particles containing water-dispersible polyurethane resin (A) and hydrophobic polyester polyol (B-1) and / or hydrophobic polyether polyol (B-2) are dispersed in water And a crosslinking agent (D) capable of reacting with a hydroxyl group,
The water-dispersible polyurethane resin (A) is obtained by reacting polyester polyol (a-1) obtained by condensing a dicarboxylic acid mainly composed of an aromatic dicarboxylic acid and a polyol and polyisocyanate as essential components. Containing 15 to 35% by weight of an aromatic cyclic structural unit,
The hydrophobic polyester polyol (B-1) and / or hydrophobic polyether polyol (B-2) is liquid at room temperature and contains 20 to 50% by weight of an aromatic cyclic structural unit. Water-based coating agent.   The aqueous coating agent according to claim 1, wherein the total content of urethane bond units and urea bond units per 1000 g of the water-dispersible polyurethane resin (A) is in the range of 1.0 to 4.0 mol.   The hydrophobic polyester polyol (B-1) is obtained by condensing a dicarboxylic acid and an aliphatic diol having 2 to 8 carbon atoms, and at least 60 mol% of the total amount of the dicarboxylic acid is orthophthalic acid. The aqueous coating agent according to claim 1.   The aqueous coating agent according to claim 1, wherein the hydrophobic polyether polyol (B-2) is a propylene oxide adduct of a polynuclear phenol compound. The water-dispersible polyurethane resin (A) is obtained by reacting polyester polyol (a-1) obtained by condensing dicarboxylic acid and polyol and polyisocyanate as essential components, and out of the total amount of dicarboxylic acid The aqueous coating agent according to claim 1, wherein 70 to 100 mol% is terephthalic acid and / or isophthalic acid. The aqueous coating according to claim 1, wherein the water-dispersible polyurethane resin (A) and the hydrophobic polyester polyol (B-1) or the hydrophobic polyether polyol (B-2) are not substantially chemically bonded. Agent. The aqueous coating agent according to claim 1 or 2, wherein the crosslinking agent (D) is at least one selected from the group consisting of amino resins and polyisocyanates.