JP2012031261A - Aqueous dispersion and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamide resin aqueous dispersion which can provide a polyamide resin coating film having good cohesiveness, flexibility, chemical resistance and heat resisting adhesion, is excellent in dispersion stability even at room temperature, and can maintain a fine particle diameter even in an acidic region; and to provide a method for producing the same.SOLUTION: The polyamide resin aqueous dispersion contains a dimmer acid-based polyamide resin which contains ≥50 mol% of the dimmer acid in the total of a dicarboxylic acid component, and has an amine value of being larger than an acid value and ≥1 mgKOH/g, an acidic compound, and an aqueous medium, wherein the number-average particle diameter of the dimmer acid-based polyamide resin is <0.5 μm.

Description

  The present invention relates to an aqueous polyamide resin dispersion exhibiting stable dispersibility in an acidic region, and specifically, a polyamide resin coating film having good adhesion, flexibility, chemical resistance, and heat-resistant adhesiveness is obtained later. It is related with the aqueous dispersion which can be used, and its manufacturing method.

  A polyamide resin having an amide bond in the main chain is a resin obtained mainly by a dehydration condensation reaction using a dicarboxylic acid component such as adipic acid or sebacic acid and a diamine component such as hexamethylenediamine or ethylenediamine. It is used in a wide range of fields such as applications and industrial applications.

  The dimer acid is a dicarboxylic acid component having 36 carbon atoms, which is obtained by dimerizing an unsaturated fatty acid having 18 carbon atoms such as oleic acid and linoleic acid, and is a plant-derived fatty acid. A dimer acid-based polyamide resin can be obtained by a condensation reaction of a dicarboxylic acid component mainly composed of dimer acid and various diamine components.

  Dimer acid-based polyamide resin is generally a resin with excellent adhesion, flexibility, chemical resistance, and heat-resistant adhesive properties, such as hot melt adhesives and additives for resin modification in a wide range of applications such as automotive parts and cables. It is used for. Another characteristic is that the resin softening point, MFR, adhesive properties, flexibility, and other characteristics can be widely controlled by the dicarboxylic acid component, diamine component, terminal acid component amount, terminal amine component amount, and the like.

  If a solution or dispersion can be obtained without impairing the properties of the dimer acid polyamide resin, for example, a dimer acid polyamide resin coating film can be easily formed on the surface of a resin film, sheet, paper, metal, etc. Adhesion, flexibility, chemical resistance, and heat-resistant adhesion can be imparted. However, dimer acid-based polyamide resins, especially those with low acid and amine values, and resins with high softening points, have poor solubility in various solvents such as alcohols and toluene, making it difficult to obtain stable solutions. It is.

  There is also an attempt to obtain a polyamide resin aqueous dispersion containing a dimer acid-based polyamide resin. For example, Patent Document 1 discusses a method of dispersing a polyamide resin having an acid value of 8 or more in an aqueous solvent containing usually 20% by mass or more of an alkylalkanolamine. Patent Documents 2 to 5 disclose methods for obtaining an aqueous dispersion of a polyamide resin containing a dimer acid-based polyamide resin.

JP-A 64-20261 JP-A-2-4862 JP-A-2-4863 JP 2000-7787 A Japanese Patent Laid-Open No. 2001-270987

  However, the aqueous dispersion obtained by the method described in Patent Document 1 has not gelled at room temperature to obtain an aqueous dispersion excellent in dispersion stability.

  In addition, in the methods described in Patent Documents 2 to 5, since an emulsifier and a surfactant are essential components, when the coating film is formed, an emulsifier and a surfactant are contained in addition to the polyamide resin component. These have the problem of adversely affecting the properties of the coating film, such as the good adhesion and chemical resistance inherent in polyamide resins. In addition, a dispersion having a low viscosity can be obtained under heating, but there is a problem that thickening starts by cooling and considerably thickens and gels at room temperature.

  Furthermore, even in the aqueous dispersion obtained without thickening at room temperature, the average particle diameter of the resin in the dispersion is 0.5 μm at the smallest, and both are excellent in dispersion stability and dense coating film. It was not an aqueous dispersion having a fine particle diameter sufficient to form a film.

  And the anionic aqueous dispersion having a pH higher than 7 has a problem that aggregation of resin particles occurs in an acidic region, and a stable dispersion shape cannot be maintained. That is, it is difficult to mix a compound, solution, dispersion, or the like that is stable only in the acidic region with an anionic aqueous dispersion and use it as a coating agent.

  The present invention solves the above-mentioned problems, and is an aqueous dispersion that can later obtain a polyamide resin coating film having good adhesion, flexibility, chemical resistance, and heat-resistant adhesiveness. Thus, an object of the present invention is to provide an aqueous polyamide resin dispersion that is excellent in dispersion stability at room temperature and that can maintain a fine particle size even in an acidic region, and a method for producing the same.

  As a result of diligent studies to solve the above problems, the present inventors can not only stably disperse fine particles in an aqueous medium but also have an acidic range by using a dimer acid-based polyamide resin having a specific composition. In addition, it has been found that an aqueous dispersion can be obtained that is stable and can be mixed with an acidic material while maintaining its stability. The inventors have also found out how to obtain without using a chemical conversion aid or a high-boiling aqueous conversion aid and means for efficiently obtaining such an aqueous dispersion, and have made the present invention.

  That is, the gist of the present invention is as follows.

(1) Dimer acid containing 50 mol% or more of the entire dicarboxylic acid component, containing a dimer acid-based polyamide resin having an amine value larger than the acid value and 1 mg KOH / g or more, an acidic compound, and an aqueous medium, A polyamide resin aqueous dispersion, wherein the dimer acid polyamide resin has a number average particle diameter of less than 0.5 μm.
(2) The polyamide resin aqueous dispersion according to the above (1), which has a boiling point at normal pressure of 185 ° C. or higher or does not contain a non-volatile aqueous dispersion aid.
(3) The polyamide resin aqueous dispersion according to (1) or (2) above, wherein the acidic compound is an organic acid.
(4) The aqueous polyamide resin dispersion according to any one of (1) to (3) above, wherein the pH is 2 to 6.
(5) The aqueous polyamide resin dispersion according to any one of (1) to (4) above, wherein the dimer acid-based polyamide resin, the acidic compound, and the aqueous medium are heated and stirred at 70 to 280 ° C. Manufacturing method.
(6) The method for producing an aqueous dispersion of polyamide resin as described in (5) above, wherein the aqueous medium contains a hydrophilic organic solvent.

In the aqueous dispersion of polyamide resin of the present invention, a dimer acid-based polyamide resin having a fine particle diameter is dispersed, and it is difficult to gel even at room temperature and has excellent dispersion stability. Further, the aqueous dispersion of the present invention is excellent in stability even in an acidic region, and can maintain its stability even when mixed with an acidic material.

  And by apply | coating the aqueous dispersion of this invention to various base materials, the precise | minute coating film of a dimer acid type polyamide resin can be obtained, and the coating film obtained is adhesiveness, a softness | flexibility, chemical resistance, Excellent heat-resistant adhesion. In particular, in the present invention, since an intended aqueous dispersion can be obtained without using an emulsifier or a surfactant, further improvements in coating film adhesion and chemical resistance can be expected.

  Furthermore, according to the production method of the present invention, the above excellent aqueous dispersion can be efficiently produced by simple means without cost.

  Hereinafter, the present invention will be described in detail.

  The aqueous polyamide resin dispersion of the present invention comprises a dimer acid-based polyamide resin containing a predetermined amount of dimer acid and having an amine value greater than the acid value and an amine value satisfying a predetermined range dispersed in an aqueous medium. is there.

  The aqueous medium in the present invention refers to water or a mixed liquid of water and an organic solvent described later.

  In the dimer acid polyamide resin in the present invention, the amine value needs to be larger than the acid value. This is because when the amine value is smaller than the acid value, the stability of the obtained aqueous dispersion in the acidic region is greatly reduced.

  The amine value of the dimer acid-based polyamide resin needs to be 1 mgKOH / g or more. When the amine value is less than 1 mg KOH / g, the stability of the aqueous dispersion is significantly reduced. The upper limit of the amine value is not particularly limited, but is practically preferably up to 50 mgKOH / g. This is because when it exceeds 50 mgKOH / g, the chemical resistance of the coating film to be produced later tends to decrease. Furthermore, considering the effect of the present invention in addition to practical use, the amine value is preferably 3 to 25 mgKOH / g, more preferably 5 to 20 mgKOH / g.

  On the other hand, the acid value of the dimer acid-based polyamide resin is preferably 40 mgKOH / g or less, more preferably 10 mgKOH / g or less, and further preferably 2 mgKOH / g or less. When the acid value exceeds 40 mgKOH / g, the chemical resistance of a coating film to be produced later tends to be lowered, which is not preferable.

  In addition, an amine value is represented by the milligram number of potassium hydroxide used as the molar equivalent with the amine component in 1g of resin. On the other hand, the acid value is defined as the number of milligrams of potassium hydroxide required to neutralize the acidic component contained in 1 g of resin. Both are measured by the method described in JIS K2501.

  The dimer acid-based polyamide resin in the present invention has an amide bond in the main chain, and is obtained mainly by a dehydration condensation reaction using a dicarboxylic acid component containing dimer acid and a diamine component. The dimer acid is obtained by dimerizing an unsaturated fatty acid having 18 carbon atoms such as oleic acid or linoleic acid, and includes those obtained by hydrogenation to reduce the degree of unsaturation.

  The dimer acid-based polyamide resin has flexibility because it has a larger hydrocarbon group than resins such as nylon 6, nylon 66, and nylon 12, which are widely used as polyamide resins. As the dimer acid, for example, a commercially available Hari dimer series (manufactured by Harima Chemicals Co., Ltd.), a pre-pole series (manufactured by Croda Japan Co., Ltd.), a tsuno dime series (manufactured by Tsukuno Food Industry Co., Ltd.), etc. can be used.

  In this invention, it is necessary to make the content rate of dimer acid among all the dicarboxylic acid components which comprise a polyamide resin into 50 mol% or more, 60 mol% or more is preferable and 70 mol% or more is more preferable. When the ratio of the dimer acid is less than 50 mol%, it becomes difficult to obtain the characteristics and effects of the dimer acid-based polyamide resin.

  Examples of dicarboxylic acid components other than dimer acid include adipic acid, azelaic acid, sebacic acid, pimelic acid, suberic acid, nonanedicarboxylic acid, and fumaric acid. The content ratio of the other dicarboxylic acid component is preferably less than 50 mol% of the entire dicarboxylic acid component, and preferably 30 mol% or less. This facilitates control of the softening point and adhesiveness of the resin. In addition, monomeric acid (monomer, carbon number 18) and trimer acid (trimer, carbon number 54), which are by-products during the production of dimer acid, and other polymerized fatty acids such as carbon number 20 to 54 are also included. The polyamide resin in the present invention may be used as one component, and the amount used is preferably 25% by mass or less based on the amount of dimer acid used.

  As the diamine component constituting the polyamide resin, ethylenediamine, hexamethylenediamine, tetramethylenediamine, pentamethylenediamine, m-xylenediamine, phenylenediamine, diethylenetriamine, piperazine and the like can be used, among which ethylenediamine, hexamethylenediamine. , Diethylenetriamine, m-xylenediamine, and piperazine are preferable.

  The polymerization degree, acid value, and amine value of the resin can be set to desired ranges by adjusting the charging ratio of the dicarboxylic acid component and the diamine component when polymerizing the resin.

  Moreover, as a softening point of the dimer acid type polyamide resin in this invention, 70-250 degreeC is preferable, 80-240 degreeC is more preferable, 80-200 degreeC is further more preferable. When the softening point is less than 70 ° C., when the coating film is formed later, the strength of the coating film tends to decrease, and the tackiness at room temperature tends to increase, which is not preferable. On the other hand, if it exceeds 250 ° C., it tends to be difficult to disperse the resin in the aqueous medium, which is not preferable.

  In addition to the above polyamide resin, the aqueous dispersion of the present invention must contain an acidic compound. By containing an acidic compound, some or all of the amino groups contained in the dimer acid-based polyamide resin are neutralized, cations are generated, and the electric repulsive force releases the aggregation between the resin fine particles, resulting in aqueous dispersion. Stability is given to the body.

  The acid dissociation constant (pKa) of the acidic compound is preferably 8 or less, more preferably -9 to 7, further preferably -5 to 6, and particularly preferably 0 to 5. When pKa exceeds 8, it is difficult to neutralize the amino group and it may be difficult to disperse the resin, which is not preferable. The lower limit of pKa is not particularly limited, but if it is too small, the corrosiveness of acidic compounds becomes strong, and equipment for aqueous dispersion or equipment for using aqueous dispersion may be damaged. It is not preferable.

  Furthermore, the acidic compound is preferably volatile. Specifically, the boiling point is preferably 20 to 250 ° C, more preferably 30 to 200 ° C, still more preferably 50 to 150 ° C, and more preferably 50 to 120 ° C. Is particularly preferred. If the acidic compound is non-volatile, that is, if the boiling point exceeds 250 ° C., it will become a coating film, and there will be a significant amount of acidic compound remaining in the coating film, which may adversely affect the adhesion and water resistance of the coating film. Yes, not preferred. On the other hand, if the boiling point of the acidic compound is too low, that is, less than 20 ° C., the neutralization efficiency may decrease as a result of volatilization of most of the acidic compound when preparing the aqueous dispersion, such being undesirable.

  Specific examples of acidic compounds having a pKa of 8 or less include organic acids such as formic acid, acetic acid, propionic acid, butyric acid and valeric acid, and inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid. Among these, organic acids having relatively low corrosivity and excellent neutralization of amino groups are preferable, and formic acid and acetic acid are particularly preferable.

  In the aqueous dispersion of the present invention, the content of the acidic compound is preferably 0.5 to 5 times equivalent mol, more preferably 0.8 to 3 times equivalent mol, based on the number of moles of amino groups of the polyamide resin. 1-2.5 times equivalent mole is more preferable. When the content of the acidic compound is less than 0.5 equivalent mole, it tends to be difficult to obtain a stable aqueous dispersion, whereas when the content exceeds 5 equivalent mole, the aqueous dispersion is colored. There is a tendency for drying time to become long, and neither is preferable.

  In the aqueous dispersion of the present invention, the amino group in the polyamide resin is neutralized with an acidic compound, and a stable form can be maintained in the acidic region. The pH of the aqueous dispersion is preferably in the range of 2-6.

  Thus, in the aqueous dispersion of the present invention, the dimer acid polyamide resin is stably dispersed in the aqueous medium, and the number average particle diameter of the dimer acid polyamide resin particles is less than 0.5 μm. It is necessary, preferably 0.4 μm or less, more preferably 0.2 μm or less, and most preferably 0.1 μm or less. When the number average particle size of the dimer acid-based polyamide resin particles is 0.5 μm or more in the aqueous dispersion, the dispersion stability and the dilution stability are lowered, and further, when formed into a coating film, the fineness is lost. The number average particle diameter of the polyamide resin particles is measured by a dynamic light scattering method. Specifically, it is measured using a Nikkiso Co., Ltd. Microtrac particle size distribution analyzer UPA150 (MODEL No. 9340).

  The aqueous dispersion of the present invention preferably has a boiling point at normal pressure of 185 ° C. or higher or does not contain a non-volatile aqueous auxiliary agent. A boiling point at normal pressure of 185 ° C. or higher or a non-volatile aqueous auxiliary agent refers to an emulsifier component or a compound having a protective colloid effect. That is, in the present invention, a stable aqueous dispersion can be obtained without using such an aqueous additive, and a stable aqueous dispersion can be obtained. Therefore, it is necessary to use such an aqueous additive. There is no. However, since the use of such an aqueous auxiliary does not immediately reduce the stability of the aqueous dispersion, the present invention does not prevent the use of such an aqueous auxiliary. However, since the aqueous dispersion of the present invention is clearly distinguished from that obtained by the method using an aqueous auxiliary agent as an essential component, it is preferable not to use an aqueous auxiliary agent as much as possible. It is particularly preferred not to do so. However, after the aqueous dispersion of the present invention is obtained, an aqueous auxiliary agent may be used positively depending on the purpose. For example, a coating containing the aqueous dispersion of the present invention as a part of the constituent components may be used. Needless to say, an aqueous auxiliary agent may be added depending on the purpose, for example, when an agent is obtained.

  Here, examples of the emulsifier component include a cationic emulsifier, an anionic emulsifier, a nonionic emulsifier, and an amphoteric emulsifier. In addition to those generally used for emulsion polymerization, surfactants are also included. For example, anionic emulsifiers include higher alcohol sulfates, higher alkyl sulfonates, higher carboxylates, alkyl benzene sulfonates, polyoxyethylene alkyl sulfate salts, polyoxyethylene alkyl phenyl ether sulfate salts, vinyl sulfosuccinates. Nonionic emulsifiers include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyethylene glycol fatty acid ester, ethylene oxide propylene oxide block copolymer, polyoxyethylene fatty acid amide, ethylene oxide-propylene oxide Examples thereof include compounds having a polyoxyethylene structure such as copolymers and sorbitan derivatives. Examples of amphoteric emulsifiers include lauryl betaine and lauryl dimethylamine oxide.

  Examples of the compound having a protective colloid include polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, modified starch, polyvinyl pyrrolidone, polyacrylic acid and salts thereof, carboxyl group-containing polyethylene wax, carboxyl group-containing polypropylene. Acid-modified polyolefin waxes having a number average molecular weight of usually 5000 or less, such as waxes, carboxyl group-containing polyethylene-propylene waxes and salts thereof, acrylic acid-maleic anhydride copolymers and salts thereof, styrene- (meth) acrylic acid copolymers Polymer, ethylene- (meth) acrylic acid copolymer, isobutylene-maleic anhydride alternating copolymer, (meth) acrylic acid- (meth) acrylic acid ester copolymer In general, a carboxyl group-containing polymer having an unsaturated carboxylic acid content of 10% by mass or more and a salt thereof, polyitaconic acid and a salt thereof, a water-soluble acrylic copolymer having an amino group, gelatin, gum arabic, casein, etc. Examples thereof include compounds used as fine particle dispersion stabilizers.

  In addition, the content (solid content concentration) of the polyamide resin in the aqueous dispersion of the present invention can be appropriately selected according to the purpose of use and the storage method, and is not particularly limited, but is 3 to 40% by mass. Among these, 10 to 35% by mass is preferable. If the content of the dimer acid polyamide resin in the aqueous dispersion is less than the above range, it may take time to form a coating film by the drying process, and it tends to be difficult to obtain a thick coating film, It is not preferable. On the other hand, when the content of the dimer acid polyamide resin in the aqueous dispersion is more than the above range, the storage stability of the dispersion tends to be lowered, which is not preferable.

  And although it does not specifically limit as a viscosity of the aqueous dispersion of this invention, It is preferable that it is a low viscosity also at room temperature. Specifically, the rotational viscosity measured at 20 ° C. using a B-type viscometer (manufactured by Tokimec, DVL-BII type digital viscometer) is preferably 100,000 mPa · s or less, more preferably 10,000 mPa · s or less, 5000 mPa · s or less is more preferable, and 1000 mPa · s or less is particularly preferable. When the viscosity of the aqueous dispersion exceeds 100,000 mPa · s, it tends to be difficult to uniformly apply the dispersion to the substrate, which is not preferable.

  Next, the manufacturing method of the polyamide resin aqueous dispersion of this invention is demonstrated.

In obtaining the aqueous dispersion of the present invention, it is preferable to use a sealable container. That is, a means for preparing each component in a sealable container, heating and stirring is preferably employed.
Specifically, after a predetermined amount of dimer acid-based polyamide resin, an acidic compound, an aqueous medium and a container are charged and the container is sealed, the temperature is preferably 70 to 280 ° C, more preferably 100 to 250 ° C. Stir with heating. When the temperature during heating and stirring is less than 70 ° C., the dispersion of the polyamide resin is difficult to proceed, and the number average particle size of the resin tends to be less than 0.5 μm. On the other hand, when the temperature exceeds 280 ° C., the polyamide The molecular weight of the resin may decrease, and the internal pressure of the system may increase to a level that cannot be ignored.

  When heating and stirring, it is preferable to heat and stir at 10 to 1000 revolutions per minute until the resin is uniformly dispersed in the aqueous medium.

  Furthermore, in the production method of the present invention, from the viewpoint of further reducing the particle size of the polyamide resin and at the same time further promoting the dispersion of the polyamide resin in the aqueous medium, it is possible to use a solution containing a hydrophilic organic solvent as the aqueous medium. preferable. The hydrophilic organic solvent means an organic solvent having a solubility in water at 20 ° C. of 50 g / L or more. In the present invention, those having a solubility of 100 g / L or more are preferred, and those having a solubility of 600 g / L or more are more preferred. In particular, those which dissolve in water at an arbitrary ratio are most preferably used.

  The boiling point of the hydrophilic organic solvent is preferably 30 to 250 ° C, more preferably 50 to 200 ° C. When the boiling point is less than 30 ° C., the hydrophilic organic solvent is likely to volatilize during the preparation of the aqueous dispersion. As a result, the meaning of using the hydrophilic organic solvent is lost, and the working environment is also easily deteriorated. Absent. On the other hand, when the temperature exceeds 250 ° C., it tends to be difficult to remove the hydrophilic organic solvent from the aqueous dispersion. As a result, when the coating film is formed later, the organic solvent remains in the coating film. Since solvent resistance may be lowered, it is not preferable.

  As a compounding quantity of a hydrophilic organic solvent, it is preferable to mix | blend in the ratio of 60 mass% or less with respect to the whole aqueous medium, 1-50 mass% is more preferable, 2-40 mass% is more preferable, 3-30 Mass% is particularly preferred. When the blending amount of the hydrophilic organic solvent exceeds 60% by mass, not only the effect of promoting aqueous formation can be expected, but also the aqueous dispersion tends to gel in some cases, such being undesirable.

  Specific examples of the hydrophilic organic solvent include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol, tert- Alcohols such as amyl alcohol, 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol, cyclohexanol; ketones such as methyl ethyl ketone, methyl isobutyl ketone, ethyl butyl ketone, cyclohexanone, isophorone; tetrahydrofuran, Ethers such as dioxane; ethyl acetate, acetic acid-n-propyl, isopropyl acetate, acetic acid-n-butyl, isobutyl acetate, acetic acid-sec-butyl, acetic acid-3-methoxybutyl, Esters such as methyl lopionate, ethyl propionate, diethyl carbonate, dimethyl carbonate; ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol ethyl ether acetate, diethylene glycol Glycol derivatives such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol ethyl ether acetate, propylene glycol, propylene glycol monomethyl ether, propylene glycol monobutyl ether, propylene glycol methyl ether acetate; 3-methoxy-3-methylbutanol, 3-methoxybutanol, acetonitrile, dimethylformamide, dimethylacetamide, diacetone alcohol, ethyl acetoacetate and the like.

  A part of the organic solvent or acidic compound blended at the time of aqueous formation can be removed from the aqueous dispersion by a solvent removal operation called stripping. By such stripping, the content of the organic solvent can be reduced to 0.1% by mass or less as necessary. Even when the content of the organic solvent is 0.1% by mass or less, the influence on the performance of the aqueous dispersion is not particularly confirmed. Examples of the stripping method include a method in which the aqueous dispersion is heated with stirring at normal pressure or reduced pressure to distill off the organic solvent. At this time, it is preferable to select a temperature and pressure at which the acidic compound is not completely distilled off. Moreover, since resin solid content concentration in an aqueous dispersion becomes high when a part of aqueous medium is distilled off simultaneously, it is preferable to adjust resin solid content concentration suitably.

  Examples of the hydrophilic organic solvent that is effective in promoting aqueous formation and that can be easily removed include, for example, ethanol, n-propanol, isopropanol, n-butanol, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, and ethylene glycol monoethyl ether. , Ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, etc. In the present invention, ethanol, n-propanol, isopropanol, tetrahydrofuran and the like are particularly preferably used.

  Further, in the production method of the present invention, for the purpose of promoting the dispersion of the resin in the aqueous medium containing the hydrophilic organic solvent, the hydrocarbon-based organic solvent such as toluene or cyclohexane is used as a whole of the components constituting the aqueous medium. You may mix | blend in 10 mass% or less of range. If the blending amount of the hydrocarbon-based organic solvent exceeds 10% by mass, separation from water becomes significant in the production process, and a uniform aqueous dispersion may not be obtained.

  The aqueous dispersion of the present invention can be obtained by the above method, but after each component is heated and stirred, the obtained aqueous dispersion may be cooled to room temperature as necessary. Of course, the aqueous dispersion of the present invention does not aggregate at all even through such a cooling process, and the stability is naturally maintained.

  In the present invention, there is basically no problem even if the aqueous dispersion is cooled and then immediately discharged and used for the next use. However, since a foreign substance and a small amount of undispersed resin may rarely remain in the container, it is preferable to provide a filtration step once before discharging the aqueous dispersion. Although it does not specifically limit as a filtration process, For example, the means of carrying out pressure filtration (for example, air pressure 0.5MPa) with a 300 mesh stainless steel filter (wire diameter 0.035mm, plain weave) is employable.

Various additives may be blended in the aqueous dispersion of the present invention depending on the use, and good dispersion stability can be maintained even when an acidic material is blended.
The aqueous dispersion of the present invention can be used mainly as a coating agent for obtaining a laminate. Then, the method to obtain a laminated body using the aqueous dispersion of this invention is demonstrated.
The laminate can be basically obtained by applying the aqueous dispersion of the present invention to a substrate and then drying it.

  As a method for applying the aqueous dispersion of the present invention to a substrate, known methods such as gravure roll coating, reverse roll coating, wire bar coating, lip coating, air knife coating, curtain flow coating, spray coating, dip coating, You can use the paint method. By these methods, the aqueous dispersion can be uniformly applied to the surface of the substrate.

  The substrate on which the aqueous dispersion is applied is not particularly limited, but for example, a substrate formed of a resin material, a glass material, a paper material, a metal material, or the like is preferable. Although it does not specifically limit as thickness of a base material, 10-1000 micrometers is preferable, 10-500 micrometers is more preferable, 10-200 micrometers is especially preferable.

  In this case, for example, as the resin material, poly (meth) acrylic resin, poly (meth) acrylonitrile resin, polystyrene resin, polysulfone resin, polyethersulfone resin, polyether resin, polymethylpentene Resin, triacetate cellulose resin, polyethylene terephthalate resin, polyurethane resin, regenerated cellulose resin, diacetyl cellulose resin, acetate butyrate cellulose resin, polyester resin, acrylonitrile-butadiene-styrene terpolymer resin, Polycarbonate resin, polyether ketone resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl alcohol resin, nylon resin, polyethylene resin, polypropylene resin, polyamide resin Polyimide-based resin, such as norbornene-based resin and the like. The resin material may be stretched. Further, the resin material may contain known additives and stabilizers such as antistatic agents, plasticizers, lubricants, antioxidants and the like. The resin material may be subjected to a corona treatment, a plasma treatment, an ozone treatment, a chemical treatment, a solvent treatment, etc. as a pretreatment on the surface in consideration of adhesion when laminated with other materials. In addition, silica, alumina, etc. may be deposited, and other layers such as a barrier layer, an easy adhesion layer, an antistatic layer, an ultraviolet absorption layer, an adhesive layer, a release layer, an antireflection layer, a hard coat layer, an antiglare layer, etc. Layers may be stacked.

  As described above, after applying the aqueous dispersion of polyamide resin of the present invention to the substrate, the aqueous medium can be removed by drying and heat treatment, and the dense dimer acid polyamide resin coating film is adhered to the substrate. Can be formed. At this time, the acidic compound in the aqueous dispersion can also be removed by performing a heat treatment for drying under the condition that the acidic compound in the aqueous dispersion is distilled off.

  Although it does not specifically limit as thickness of the polyamide resin coating film formed in a base material, It is preferable to set it as the range of 0.05-20 micrometers, and it is more preferable that it is 0.1-10 micrometers. If the thickness is less than 0.05 μm, the properties of the polyamide resin coating film may not be sufficiently expressed. If the thickness exceeds 20 μm, the properties (effects) of the polyamide resin coating film may be saturated, which may be disadvantageous in terms of cost. Is also not preferred.

Hereinafter, the present invention will be described specifically by way of examples. In addition, measurement and evaluation of various values in the examples were performed as follows.

(1) Characteristic values of polyamide resin [acid value, amine value]
It was measured by the method described in JIS K 2501.
[Softening point temperature]
Using 10 mg of resin as a sample, using a microscope equipped with a microscope heating (cooling) apparatus heat stage (Heating-Freezing AGE TH-600, manufactured by Linkham Co., Ltd.), measurement was performed at a temperature rising rate of 20 ° C./min. The temperature at which the resin melted was defined as the softening point.
[Melt viscosity]
It was measured with a Brookfield melt viscometer DV-II + PRO type at a resin temperature of 200 ° C. and a shear rate of 1.25 / sec. After starting the melting, it was rotated for about 25 minutes, and the value of the melt viscosity at the time when the viscosity was stabilized at almost the elapsed time was read.

(2) Solid Content Concentration of Aqueous Dispersion An appropriate amount of the obtained aqueous dispersion was weighed and heated at 150 ° C. until the mass of the residue (solid content) reached a constant weight to obtain the solid content concentration.

(3) Dispersion stability of aqueous dispersion The obtained aqueous dispersion was allowed to stand at room temperature for 10 days, and the appearance of the aqueous dispersion was evaluated in the following three stages.
○: No change in appearance, △: Separation, partial gelation, ×: Complete gelation, occurrence of aggregates

(4) pH of aqueous dispersion
The pH was measured using a pH meter (Horiba, Ltd., F-52).

(5) Viscosity of aqueous dispersion The viscosity was measured by the method described above.

(6) Number average particle diameter of polyamide resin in aqueous dispersion Measured by the above method.

(7) Adhesion Using a soft vinyl chloride sheet as a base material, and using a wire bar so that the thickness of the resin layer after drying the obtained polyamide resin aqueous dispersion is 3 μm on one side of the base material The dimer acid-based polyamide resin coating film was formed on the surface of the soft vinyl chloride sheet by coating and heating and drying at 120 ° C. for 1 minute. About the coating film of the obtained laminated body, according to the method of JISK5600, adhesiveness was evaluated in the following four steps by the crosscut method.
A: No peeling is observed on any lattice.
○: Slight peeling is seen along the edge of the lattice cut. Less than 5% of the total.
(Triangle | delta): About 5-15% of peeling of the whole is seen.
X: Peeling of 15% or more of the whole is observed.

(8) Stability of mixing with acidic material The presence or absence of agglomerates when the aqueous acidic resin dispersion was mixed and stirred in the aqueous polyamide resin dispersion was evaluated in the following three stages.
○: No aggregate, Δ: Slightly aggregate, ×: Aggregate

Example 1
(P-1) was used as a polyamide resin.

  P-1: As dicarboxylic acid component, dimer acid is contained at 90 mol%, azelaic acid is contained at 10 mol%, and diamine component is contained at 50 mol% piperazine, and ethylenediamine is contained at 50 mol%, with an acid value of 0.3 mgKOH / g. , Amine value 15.5 mg KOH / g, softening point 135 ° C., melt viscosity at 230 ° C. 4500 mPa · s.

  At the time of production of P-1, “Tsunodaim 395 (trade name)” manufactured by Tsukino Food Industry Co., Ltd. was used as a dimer acid raw material (94% by mass of dimer acid, 3% by mass of monomer acid, and 3% by mass of trimer acid) ).

  In a sealable 1 liter pressure-resistant glass container equipped with a stirrer and a heater, 75 g of the above P-1 and 1.9 g of formic acid (made by Wako Pure Chemicals, pKa = 3.75) as an acidic compound (amino group of polyamide resin) 23.8 equivalent moles), 93.8 g of tetrahydrofuran (manufactured by Wako Pure Chemical Industries, Ltd., hereinafter sometimes referred to as THF) as a hydrophilic organic solvent, and 204.3 g of distilled water, The mixture was sealed and mixed with stirring at a rotation speed of 300 rpm. At this time, it was confirmed that no sedimentation of resin particles was observed at the bottom of the container due to stirring, and that the suspension was in a floating state. Therefore, the heater was turned on, the temperature in the container was set to 120 ° C., and the mixture was further stirred for 60 minutes. Thereafter, the mixture was cooled to near room temperature (about 30 ° C.) with stirring, 150 g of distilled water was added, transferred to a 1 L eggplant flask, decompressed using an evaporator while attached to a hot water bath heated to 80 ° C., and THF and water In total, about 150 g was distilled off (solvent removal). Thereafter, the mixture was filtered through a 300 mesh stainless steel filter (wire diameter 0.035 mm, plain weave) with very slight pressure to obtain a brown uniform polyamide resin aqueous dispersion E-1.

(Example 2)
Example 1 except that 2.5 g of acetic acid (manufactured by Wako Pure Chemical Industries, pKa = 4.76) (2 equivalent moles relative to the number of moles of amino groups of the polyamide resin) was used instead of 1.9 g of formic acid. The same operation was performed to obtain a milky yellow uniform polyamide resin aqueous dispersion E-2.

(Comparative Example 1)
(P-2) was used as the polyamide resin.

  P-2: As dicarboxylic acid component, dimer acid is contained at 90 mol%, azelaic acid is contained at 10 mol%, and as diamine component, piperazine is contained at 50 mol%, ethylenediamine is contained at 50 mol%, and the acid value is 10.0 mgKOH / g. , Amine value 0.1 mg KOH / g, softening point 135 ° C., melt viscosity at 230 ° C. 4200 mPa · s.

  At the time of P-2 production, “Tsunodaim 395 (trade name)” manufactured by Tsukino Food Industries Co., Ltd. was used as a dimer acid raw material (94% by weight of dimer acid, 3% by weight of monomer acid, and 3% by weight of trimer acid) ).

  Thereafter, an attempt was made to prepare an aqueous polyamide resin dispersion by the same method as in Example 1 except that P-2 was used instead of P-1. However, a resin mass remained and an aqueous dispersion was not obtained.

(Comparative Example 2)
In a sealable 1 liter pressure-resistant glass container equipped with a stirrer and a heater, 75 g of P-2, 37.5 g of isopropanol, 37.5 g of THF, N, N-dimethylethanolamine (manufactured by Wako Pure Chemical Industries, Ltd.) 7.5 g and 217.8 g of distilled water were charged. Then, the system was heated while stirring at a rotational speed of 300 rpm, and heated and stirred at 120 ° C. for 60 minutes. Thereafter, the mixture is cooled to around room temperature (about 30 ° C.) with stirring, 150 g of distilled water is added, transferred to a 1 L eggplant flask, decompressed using an evaporator while attached to a hot water bath heated to 80 ° C., and then subjected to IPA, THF And 150 g of water were distilled off (solvent removal). Subsequently, the mixture was filtered through a 300-mesh stainless steel filter (wire diameter 0.035 mm, plain weave) with very slight pressure to obtain a milky-yellow uniform polyamide resin aqueous dispersion E-3.

  Table 1 shows the characteristic values and evaluation results of the aqueous dispersions obtained in Examples 1 and 2 and Comparative Examples 1 and 2.

(Example 3)
First, as an acidic material, a cationic ester-type urethane resin aqueous dispersion U-1 (“Hydran CP7050 (trade name)” manufactured by DIC) was prepared. The pH of U-1 was 5.0, and the solid content concentration was 25% by mass.

  Next, E-1 and U-1 were mixed with stirring. At this time, it mixed so that the resin solid content of U-1 might be 10 mass parts with respect to 100 mass parts of resin solid content of E-1.

(Example 4, Comparative Example 3)
A mixture was obtained in the same manner as in Example 3 except that E-2 (Example 4) and E-3 (Comparative Example 3) were used instead of E-1.

(Examples 5 and 6, Comparative Example 4)
Examples 3, 4 and Comparative Example except that a cationic type acrylic resin aqueous dispersion (“UW-223XS (trade name)” manufactured by Taisei Fine Chemical Co., Ltd., pH 4.0, solid content concentration: 34% by mass) is used instead of U-1. It carried out like Example 3 and obtained 3 types of mixtures (Example 5, 6 and Comparative Example 4) sequentially.

  Hereinafter, Table 2 shows the mixing stability of the mixtures obtained in Examples 3 to 6 and Comparative Examples 3 and 4.

  As shown in Table 1, the aqueous dispersions of the present invention (Examples 1 and 2) use a dimer acid-based polyamide resin having a specific composition, are excellent in stability, and the resin has a fine particle size. It was confirmed that they were dispersed. Moreover, the objective aqueous dispersion was able to be obtained, without using non-volatile aqueous | water-based auxiliary agents, such as surfactant. Furthermore, the obtained aqueous dispersion showed acidity, and as shown in Examples 3 to 6, even when mixed with an acidic material, good stability could be maintained. In addition, the adhesiveness of the coating film with the laminate later was also excellent.

On the other hand, in Comparative Example 1, the amine value of the resin was smaller than the acid value, and the stability in the acidic region was greatly reduced. As a result, an aqueous dispersion could not be obtained. In Comparative Example 2, although an aqueous dispersion could be obtained, it showed alkalinity, and as in Comparative Examples 3 and 4, there was a problem in terms of mixing stability with acidic materials.

Claims (6)

  Dimer acid containing 50 mol% or more of dicarboxylic acid component as a whole, containing dimer acid polyamide resin having an amine value larger than acid value and 1 mgKOH / g or more, an acidic compound, and an aqueous medium, A polyamide resin aqueous dispersion, wherein the polyamide resin has a number average particle diameter of less than 0.5 μm.   2. The polyamide resin aqueous dispersion according to claim 1, which has a boiling point of 185 ° C. or higher or a non-volatile aqueous dispersion aid at normal pressure.   The aqueous dispersion of polyamide resin according to claim 1 or 2, wherein the acidic compound is an organic acid.   pH is 2-6, The polyamide resin aqueous dispersion in any one of Claims 1-3 characterized by the above-mentioned.   The method for producing an aqueous polyamide resin dispersion according to any one of claims 1 to 4, wherein the dimer acid polyamide resin, the acidic compound, and the aqueous medium are heated and stirred at 70 to 280 ° C. 6. The method for producing an aqueous dispersion of polyamide resin according to claim 5, wherein the aqueous medium contains a hydrophilic organic solvent.