JP2012233082A - Aqueous dispersion, and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamide resin aqueous dispersion excellent in dispersion stability even at room temperature, and being capable of maintaining a fine particle diameter even in a weak acidic range; and to provide a method for producing the same.SOLUTION: The polyamide resin aqueous dispersion contains: a dimmer acid-based polyamide resin containing ≥50 mol% of a dimmer acid with respect to the whole of dicarboxylic acid components, and having a higher amine value than the acid value and an amine value of ≥1 mgKOH/g; a lactic acid; and an aqueous medium. The production method includes heating and stirring a dimmer acid-based polyamide resin, lactic acid and an aqueous medium at 70 to 280°C.

Description

  The present invention relates to an aqueous dispersion containing a polyamide resin having good adhesion, flexibility, chemical resistance and heat-resistant adhesion and lactic acid, and an aqueous polyamide resin having excellent dispersion stability in a weakly acidic region at room temperature. The present invention relates to a dispersion and a method for producing the same.

  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 between 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 adhesion, and it can be used as a hot-melt adhesive for a wide range of applications such as automotive parts and cables, and additives for resin modification. It is used. 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 have poor solubility in various solvents such as alcohols and toluene, and it is difficult to obtain a stable solution.

  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 medium containing 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, all obtained by the methods described in Patent Documents 2 to 5 are polyamide resin aqueous dispersions containing an emulsifier and a surfactant. Such a dispersion has a low viscosity under heating, but may increase in viscosity upon cooling and may considerably increase in viscosity or gel at room temperature. Furthermore, even if the thickening at room temperature can be suppressed by adjusting the components, the average particle diameter of the resin in the dispersion is 0.5 μm even at the smallest, both of which contribute to dispersion stability. It could not be said to be an aqueous dispersion having a fine particle diameter sufficient to form an excellent dense coating 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. In other words, it is difficult to mix with a compound, solution, dispersion, or the like that is stable only in the acidic range and use it as a coating agent.

  There is also an attempt to obtain a cationic aqueous dispersion having a pH of less than 7, and although it is stable in an acidic region where the pH is less than 5, it is poor in stability in a weakly acidic region where the pH is 5 or more and close to neutrality. There was a problem.

  Furthermore, a polyamide resin aqueous dispersion having a boiling point of 185 ° C. or higher at normal pressure or substantially not containing a non-volatile aqueous dispersion aid has been obtained. When the solvent is removed by volatilization, the organic acid added to impart dispersibility volatilizes together with the organic solvent, thereby causing problems that aggregates are generated in the dispersion or the dispersion is solidified. .

  The present invention solves the above-described problems, and is an aqueous polyamide resin dispersion that is excellent in dispersion stability even at room temperature and that can maintain a fine particle size even in a weakly acidic region, and a method for producing the same. It is a technical challenge to provide

  As a result of intensive studies to solve the above problems, the present inventors have found that a resin having a small particle diameter can be stably dispersed in an aqueous medium by using a dimer acid-based polyamide resin having a specific composition and lactic acid. I found it.

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

(1) A dimer acid containing 50 mol% or more of the whole dicarboxylic acid component, containing a dimer acid polyamide resin having an amine value larger than the acid value and 1 mg KOH / g or more, lactic acid, and an aqueous medium An aqueous polyamide resin dispersion.
(2) The aqueous polyamide resin dispersion according to (1), comprising a dimer acid-based polyamide resin having an amine value of 5 to 20 mgKOH / g.
(3) The polyamide resin aqueous dispersion as described in (1) or (2) above, wherein the number average particle diameter of the polyamide resin in the aqueous dispersion is less than 0.5 μm.
(4) The aqueous polyamide resin dispersion according to any one of (1) to (3) above, wherein the pH is 5 to 7.
(5) The aqueous polyamide resin dispersion according to any one of the above (1) to (4), wherein the aqueous medium contains a hydrophilic organic solvent.
(6) The method for producing an aqueous dispersion of polyamide resin as described in (1) above, wherein the dimer acid-based polyamide resin, lactic acid, and an aqueous medium are heated and stirred at 70 to 280 ° C.

The aqueous dispersion of polyamide resin of the present invention has a dispersion of a dimer acid polyamide resin having a fine particle size, does not gel at room temperature, and has excellent dispersion stability. Therefore, by applying the aqueous dispersion of polyamide resin of the present invention, it is possible to obtain a dense coating film of dimer acid-based polyamide resin, and the coating film obtained has adhesion, flexibility and chemical resistance. Excellent heat resistance.

  In addition, according to the present invention, an aqueous polyamide resin dispersion that does not gel at room temperature and has excellent dispersion stability in a weakly acidic region having a pH of 5 to 7 that could not be obtained conventionally can be obtained. . Furthermore, even when part of the organic solvent is volatilized and removed by heating in the manufacturing process, the component added for imparting dispersibility is hardly volatilized, and as a result, an aqueous polyamide resin dispersion having good dispersibility is obtained. be able to.

  Hereinafter, the present invention will be described in detail.

  The aqueous polyamide resin dispersion of the present invention contains a dimer acid-based polyamide resin containing a predetermined amount of dimer acid, an amine value greater than the acid value, and an amine value satisfying a predetermined range, lactic acid, and an aqueous medium. It is a waste.

  The aqueous medium in the present invention refers to water or a mixed liquid of water and an organic solvent described later, and the content of the organic solvent is generally preferably less than 50% by mass.

  In the 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 weakly acidic region is greatly reduced.

  The amine value of the 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 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 polyamide resin in the present invention has an amide bond in the main chain, and is obtained by a dehydration condensation reaction mainly 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 polyamide resin in the present invention 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 general 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 components needs to be less than 50 mol% of the entire dicarboxylic acid component, and is preferably 25 mol% or less, which makes it easy to control the softening point and adhesiveness of the resin. Become. 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 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.

  The aqueous dispersion of the present invention must contain lactic acid in addition to the above polyamide resin. By containing lactic acid, some or all of the amine 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.

  In the aqueous dispersion of the present invention, the content of lactic acid 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 the amine group of the polyamide resin. 1-2.5 times equivalent mole is more preferable. If the content of lactic acid is less than 0.5 equivalent mol, it tends to be difficult to obtain a stable aqueous dispersion. On the other hand, if the content of lactic acid exceeds 5 equivalent mol, the aqueous dispersion is colored, and the pH decreases. There is a tendency to be too much, and neither is preferable.

  In the aqueous dispersion of the present invention, the amine group in the polyamide resin is neutralized with lactic acid, and a stable form can be maintained in a weakly acidic region. The pH of the aqueous dispersion is preferably in the range of 3 to 7, and more preferably in the range of 5 to 7.

  Thus, in the aqueous dispersion of the present invention, the polyamide resin is stably dispersed in the aqueous medium. The number average particle diameter of the polyamide resin particles is preferably less than 0.5 μm, more preferably 0.4 μm or less, still more preferably 0.2 μm or less, and most preferably 0.1 μm or less. When the number average particle diameter of the polyamide resin particles is 0.5 μm or more in the aqueous dispersion, the dispersion stability and the dilution stability are lowered, and there is a possibility that the coating film lacks the denseness. 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).

  Further, the aqueous dispersion of the present invention can be obtained without including an emulsifier or surfactant generally used for emulsion polymerization, such as a cationic emulsifier, an anionic emulsifier, a nonionic emulsifier or an amphoteric emulsifier, or a compound having a protective colloid. Can do. 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, a predetermined amount of polyamide resin, lactic acid, and an aqueous medium are put into a container and the container is sealed, and then heated and stirred at a temperature of preferably 70 to 280 ° C, more preferably 100 to 250 ° C. To do. If the temperature during heating and stirring is less than 70 ° C, the dispersion of the polyamide resin tends to be difficult to proceed. On the other hand, if the temperature exceeds 280 ° C, the molecular weight of the polyamide resin may be reduced, and the internal pressure of the system is ignored. It may rise to the extent that it cannot be done, and neither is desirable.

  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 50 mass% or less with respect to the whole aqueous medium, 2-40 mass% is more preferable, 3-30 mass% is especially preferable. When the blending amount of the hydrophilic organic solvent exceeds 50% by mass, not only is the effect of promoting aqueous formation not expected, but the aqueous dispersion tends to gel in some cases, which is not preferable.

  Specific examples of the hydrophilic organic solvent include methanol, ethanol, n-propanol (NPA), isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol. , Tert-amyl alcohol, 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol, cyclohexanol and other alcohols; methyl ethyl ketone, methyl isobutyl ketone, ethyl butyl ketone, cyclohexanone, isophorone and other ketones Ethers such as tetrahydrofuran (THF) and dioxane; ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, acetic acid -Esters such as methoxybutyl, methyl propionate, 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, 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, etc. Lumpur derivatives; more, 3-methoxy-3-methylbutanol, 3-methoxybutanol, acetonitrile, dimethylformamide, dimethylacetamide, diacetone alcohol, ethyl acetoacetate and the like.

  A part of the organic solvent blended in the aqueous process 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. In this regard, in the conventional method, formic acid, acetic acid, and the like have been used as acidic compounds added for imparting dispersibility. However, depending on heating / depressurization conditions, these compounds are likely to volatilize with an organic solvent, and the dispersion is stable. It was easy to reduce the property. In contrast, in the present invention, since lactic acid is used as the acidic compound, the acidic compound is difficult to volatilize during the stripping process, which can contribute to maintaining the stability of the dispersion.

  In addition, when the dispersion is stripped, a part of the aqueous medium is distilled off at the same time, which may increase the resin solids concentration in the aqueous dispersion. Therefore, the resin solids concentration can be adjusted appropriately. preferable.

  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.

  Moreover, various additives may be blended in the aqueous dispersion of the present invention depending on the application, and good dispersion stability can be maintained even when an acidic or neutral material is blended.

  Furthermore, the aqueous dispersion of the present invention preferably contains a crosslinking agent. By including a crosslinking agent in the aqueous dispersion, the resulting coating film can have low fluidity even at high temperatures above the softening point of the resin.

  In the present invention, any crosslinking agent can be used as long as it can crosslink dimer acid-based polyamide resins. For example, a hydrazide compound, an isocyanate compound, a melamine compound, a urea compound, an epoxy compound, a carbodiimide compound, Oxazoline compounds are preferable, and epoxy compounds are particularly preferable. These compounds can be used alone or in combination.

  Further, when a crosslinking agent having a plurality of functional groups that react with amino groups in the molecule is used as the crosslinking agent, it can be efficiently reacted with the amino groups in the polyamide resin. In addition, as the crosslinking agent, those having a self-crosslinking property or those having a polyvalent coordination site can be used.

  Any crosslinking agent can be used as long as it can crosslink dimer acid-based polyamide resins. For example, a hydrazide compound, an isocyanate compound, a melamine compound, a urea compound, an epoxy compound, a carbodiimide compound, and an oxazoline compound can be used. Of these, epoxy compounds are preferred. These compounds can be used alone or in combination.

  Moreover, when a crosslinking agent having a plurality of functional groups that react with amino groups in the molecule is used as the crosslinking agent, it can be efficiently reacted with the amino groups in the dimer acid polyamide resin. In addition, as the crosslinking agent, those having a self-crosslinking property or those having a polyvalent coordination site can be used.

  In the present invention, a commercially available crosslinking agent may be used because it is easily available. Specific examples of the hydrazide compound include APA series (APA-M950, APA-M980, APA-P250, APA-P280, etc.) manufactured by Otsuka Chemical Co., Ltd., and the isocyanate compound includes a basonate manufactured by BASF. (BASONAT) PLR 8878, Bassonate HW-100, Bayhydur 3100 manufactured by Sumitomo Bayer Urethane Co., Ltd., and Bihydur VPLS 2150/1 are listed. DIC's becamine series, and epoxy compounds include Denasel series (EM-150, EM-101, etc.) manufactured by Nagase Chemtech, Adeka Resin EM-051 manufactured by ADEKA. , EM-0526, EM-051R, EM-11-50B, and the like. Examples of the carbodiimide compound include Nisshinbo's Carbodilite series (SV-02, V-02, V-02-L2, V-04). E-01, E-02, V-01, V-03, V-07, V-09, V-05) and the like. As the oxazoline compound, EPOCROSS series (WS-500 manufactured by Nippon Shokubai Co., Ltd.) can be used. WS-700, K-1010E, K-1020E, K-1030E, K-2010E, K-2020E, K-2030E) and the like. These are commercially available as dispersions or solutions containing a cross-linking agent.

  The content of the crosslinking agent in the aqueous dispersion is preferably 0.5 to 100 parts by mass with respect to 100 parts by mass of the polyamide resin. When the content of the crosslinking agent is less than 0.5 parts by mass, it becomes difficult to obtain a desired low fluidity at high temperature in the coating film, whereas when it exceeds 100 parts by mass, the liquid stability and processability of the aqueous dispersion are decreased. As a result, the basic performance as a coating film becomes difficult to obtain.

  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 or a glass material is suitable. 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.

  The substrate is generally formed from a resin material. Resin materials include 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, poly Ether ketone resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyvinyl alcohol resin, nylon resin, polyethylene resin, polypropylene resin, polyamide resin, polyimide 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 polyamide resin dispersion of the present invention to a substrate, the aqueous medium can be removed by drying and heat treatment, and a dense polyamide resin coating film is formed in close contact with the substrate. can do.

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

(4) Viscosity of aqueous dispersion Measured by the method described above.

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

(6) 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

(7) Peel strength Copper foil (thickness 20 μm) is used as a base material, and a wire bar is used on one side of the base material so that the thickness of the resin layer after drying the aqueous dispersion obtained is 3 μm. The coating film was formed on the surface of the copper foil by heating and drying at 120 ° C. for 1 minute. Next, the same copper foil as described above was placed on the surface of the coating film, and pressed at 160 ° C. using a heat press (sealing pressure 0.2 MPa for 30 seconds).
A measurement sample having a width of 15 mm and a length of 10 cm was cut out from the obtained copper laminate, and T was used at room temperature and at a pulling speed of 200 mm / min using a tensile testing machine (precision universal material testing machine 2020 manufactured by Intesco). The peel strength was measured by performing a mold peel test, and the adhesion was evaluated based on the magnitude of the peel strength. In the measurement, five samples were collected, and the average value was taken as the peel strength.

(8) Flexibility Using a soft vinyl chloride sheet as a base material, the obtained aqueous dispersion was applied to one side of the base material using a wire bar so that the thickness of the resin layer after drying was 3 μm. By performing a heat drying treatment at 120 ° C. for 1 minute, a resin coating film was formed on the surface of the soft vinyl chloride sheet to obtain a laminate.
This was processed 100 times with a Gelboflex tester (20 ° C, 40 reciprocations per minute with a stroke of about 15 cm), and then in accordance with the method described in JIS K5600, by the cross-cut method, the following four steps The adhesiveness was evaluated by using it as an index of the flexibility of the coating film.

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.

(9) Alkali resistance An aluminum foil was used as a base material, and the obtained aqueous dispersion was applied to one side of the base material using a wire bar so that the thickness of the resin layer after drying was 2 μm. A resin coating film was formed on the surface of the aluminum foil by heat-drying at 1 ° C. for 1 minute. Then, after immersion for 3 minutes at 50 ° C. in an aqueous NaOH solution (adjusted to pH 12.0 at 20 ° C.), the presence or absence of dissolution or peeling of the coating film was visually evaluated.
○: No change in appearance.
X: The coating film is dissolved, peeled off or whitened.

  The following P-1 to P-8 were used as the polyamide resin.

  At the time of production of P-1 to P-8, as a dimer acid raw material, “Tsunodaim 395 (trade name)” manufactured by Tsukino Food Industry Co., Ltd. (94% by mass of dimer acid, 3% by mass of monomer acid, 3% of trimer acid) (Mass% content) was used.

[Polyamide resin P-1]
The dicarboxylic acid component contains 90 mol% dimer acid, 10 mol% azelaic acid, the diamine component contains 60 mol% piperazine, 40 mol% ethylenediamine, the acid value is 0.4 mgKOH / g, and the amine value is 15 Polyamide resin having a melt viscosity of 3300 mPa · s at 0.0 mg KOH / g, a softening point of 90 ° C. and 230 ° C.

[Polyamide resin P-2]
The dicarboxylic acid component contains 90 mol% dimer acid, 10 mol% azelaic acid, the diamine component contains 50 mol% piperazine, 50 mol% ethylenediamine, the acid value is 0.3 mgKOH / g, and the amine value is 15 Polyamide resin having a melt viscosity of 4500 mPa · s at 0.5 mg KOH / g, softening points of 135 ° C. and 230 ° C.

[Polyamide resin P-3]
The dicarboxylic acid component contains 80 mol% dimer acid, 20 mol% azelaic acid, the diamine component contains 50 mol% piperazine, 50 mol% ethylenediamine, the acid value is 0.1 mgKOH / g, and the amine value is 15 Polyamide resin having a melt viscosity of 5500 mPa · s at 0.0 mg KOH / g, softening points of 190 ° C. and 230 ° C.

[Polyamide resin P-4]
The dicarboxylic acid component contains 90% by mole of dimer acid and 10% by mole of azelaic acid, the diamine component contains 50% by mole of piperazine and 50% by mole of ethylenediamine, the acid value is 0.1 mgKOH / g, and the amine value is 29. Polyamide resin having a melt viscosity of 3900 mPa · s at 0.0 mg KOH / g, softening points of 138 ° C. and 230 ° C.

[Polyamide resin P-5]
The dicarboxylic acid component contains 90 mol% dimer acid, 10 mol% azelaic acid, the diamine component contains 50 mol% piperazine, 50 mol% ethylenediamine, the acid value is 0.4 mgKOH / g, and the amine value is 48. Polyamide resin having a melt viscosity of 3,800 mPa · s at 0.0 mg KOH / g, softening points of 140 ° C. and 230 ° C.

[Polyamide resin P-6]
The dicarboxylic acid component contains 90 mol% dimer acid, 10 mol% azelaic acid, the diamine component contains 50 mol% piperazine, 50 mol% ethylenediamine, the acid value is 0.2 mgKOH / g, and the amine value is 60. Polyamide resin having a melt viscosity of 4400 mPa · s at 0.0 mg KOH / g, softening points of 133 ° C. and 230 ° C.

[Polyamide resin P-7]
The dicarboxylic acid component contains 45 mol% dimer acid, 55 mol% azelaic acid, the diamine component contains 50 mol% piperazine, 50 mol% ethylenediamine, the acid value is 0.2 mgKOH / g, and the amine value is 15 Polyamide resin having a melt viscosity of 4000 mPa · s at 2 mg KOH / g, softening points of 130 ° C. and 230 ° C.

[Polyamide resin P-8]
The dicarboxylic acid component contains 90 mol% dimer acid, 10 mol% azelaic acid, the diamine component contains 50 mol% piperazine, 50 mol% ethylenediamine, the acid value is 0.2 mgKOH / g, and the amine value is 0. Polyamide resin having a melt viscosity of 4200 mPa · s at 0.5 mg KOH / g, softening points of 135 ° C. and 230 ° C.

Example 1
In a sealable 1-liter pressure-resistant glass container equipped with a stirrer and a heater, 80 g of polyamide resin P-1 and 1.9 g of lactic acid (manufactured by Wako Pure Chemical Industries) as an acidic compound (in terms of the number of moles of amine groups of the polyamide resin) After adding 80 g of NPA as a hydrophilic organic solvent and 238 g of distilled water, the vessel was sealed, and the stirring blade was rotated at a rotation speed of 300 rpm and mixed. 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. Then, it is cooled to around room temperature (about 30 ° C) with stirring, filtered through a 300 mesh stainless steel filter (wire diameter 0.035 mm, plain weave) with very slight pressure, and a milky yellow uniform polyamide resin aqueous dispersion Body E-1 was obtained.

  Table 1 shows the characteristic values and evaluation results of the aqueous dispersion obtained in Example 1.

(Example 2)
By the same method as in Example 1 except that P-2 is 80 g as the polyamide resin and 2.0 g of lactic acid as the acidic compound is 1.0 g (1.0 times equivalent mol to the number of moles of the amine group of the polyamide resin). A milky white uniform polyamide resin aqueous dispersion E-2 was obtained.

(Example 3)
400 g of E-2 was put into a 1 L eggplant flask, 120 g of water was added thereto, and the pressure was reduced using an evaporator while being put in a hot water bath heated to 95 ° C., and about 120 g of a mixed medium of NPA and water was distilled off, Uniform polyamide resin aqueous dispersion E-2-1 was obtained.

(Comparative Example 1)
In a sealable 1 liter pressure-resistant glass container equipped with a stirrer and a heater, 80 g of polyamide resin P-2 and 0.9 g of formic acid (manufactured by Wako Pure Chemical Industries) as an acidic compound (based on the number of moles of the amine group of the polyamide resin) After adding 80 g of NPA as a hydrophilic organic solvent and 239 g of distilled water, the vessel was sealed, and the stirring blade was rotated at a rotation speed of 300 rpm and mixed. 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. Then, it is cooled to around room temperature (about 30 ° C) with stirring, filtered through a 300 mesh stainless steel filter (wire diameter 0.035 mm, plain weave) with very slight pressure, and a milky yellow uniform polyamide resin aqueous dispersion Got the body.

  400 g of the obtained aqueous dispersion was put into a 1 L eggplant flask, 120 g of water was added thereto, and the pressure was reduced using an evaporator while being attached to a hot water bath heated to 95 ° C., and about 120 g of a mixed medium of NPA and water was distilled off. However, resin agglomerates were generated (this is referred to as E-2-2).

Example 4
In a sealable 1 liter pressure-resistant glass container equipped with a stirrer and a heater, 70 g of polyamide resin P-3 and 4.2 g of lactic acid (manufactured by Wako Pure Chemical Industries) as an acidic compound (in moles of amine groups of the polyamide resin) After adding 70 g of THF as a hydrophilic organic solvent and 206 g of distilled water, the vessel was sealed, and the stirring blade was rotated at a rotational speed of 300 rpm and mixed. 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 around room temperature (about 30 ° C.) with stirring, and filtered with a 300 mesh stainless steel filter (wire diameter 0.035 mm, plain weave) with very slight pressure to obtain an aqueous dispersion.

  350 g of the obtained aqueous dispersion was put into a 1 L eggplant flask, 105 g of water was added thereto, and the pressure was reduced using an evaporator while being attached to a hot water bath heated to 95 ° C., and about 105 g of a mixed medium of THF and water was distilled off. A milky white uniform polyamide resin aqueous dispersion E-3 was obtained.

(Example 5)
The same method as in Example 1 except that 80 g of P-4 is used as the polyamide resin and 3.7 g of lactic acid is used as the acidic compound (1.0 times equivalent mol to the number of moles of the amine group of the polyamide resin). A milky yellow uniform polyamide resin aqueous dispersion E-4 was obtained.

(Example 6)
By the same method as in Example 1 except that P-5 is 80 g as the polyamide resin and 3.1 g of lactic acid as the acidic compound (0.5 times equivalent mol to the number of moles of the amine group of the polyamide resin). A milky yellow uniform polyamide resin aqueous dispersion E-5 was obtained.

(Example 7)
The same method as in Example 1 except that P-6 is 80 g as the polyamide resin and lactic acid is 3.9 g as the acidic compound (0.5 mole equivalent to the number of moles of the amine group of the polyamide resin). A milky yellow uniform polyamide resin aqueous dispersion E-6 was obtained.

(Comparative Example 2)
As a polyamide resin, a milky white uniform polyamide resin aqueous dispersion E-7 was obtained in the same manner as in Example 1 except that P-7 was changed to 80 g.

(Comparative Example 3)
The same method as in Example 1 was attempted except that 80 g of P-8 was used as the polyamide resin, and 1.3 g of lactic acid was used as the acidic compound (20 times equivalent mol to the number of moles of the amine group of the polyamide resin). However, a lump of resin remained, and a good aqueous polyamide resin dispersion could not be obtained.

  As shown in Table 1, the aqueous dispersions (Examples 1 to 7) of the present invention contain a dimer acid-based polyamide resin having a specific composition and lactic acid, and are excellent in stability. It was confirmed that they were dispersed.

  In particular, the polyamide resin aqueous dispersions obtained in Examples 1 to 3 and Examples 5 and 6 exhibited weak acidity with a pH of 5 to 7.

  Moreover, in Examples 3 and 4, when preparing an aqueous dispersion, an aqueous dispersion having a good stability was obtained despite the process of volatilizing and removing a part of the solvent. In Comparative Example 1, formic acid was used in place of lactic acid, so that a part of the formic acid was volatilized by heating at 95 ° C., so that the stability of the aqueous dispersion was greatly reduced.

  In Examples 5 to 7, good polyamide resin aqueous dispersions were obtained. About the alkali resistance of the polyamide resin coating film formed using the aqueous dispersion, a slightly decreasing tendency was observed only in Example 7 in which the amine value was 60.0 mgKOH / g.

  In Comparative Example 2, a good aqueous dispersion was obtained. However, since the polyamide resin used did not contain 50 mol% or more of dimer acid in the whole dicarboxylic acid component, the coating film was inferior in flexibility.

In Comparative Example 3, since the amine value of the polyamide resin was not 1 mgKOH / g or more, an aqueous dispersion could not be obtained.

Claims (6)

A polyamide comprising a dimer acid-based polyamide resin containing dimer acid in an amount of 50 mol% or more of the total dicarboxylic acid component, having an amine value larger than the acid value and 1 mgKOH / g or more, lactic acid, and an aqueous medium Resin aqueous dispersion. The polyamide resin aqueous dispersion according to claim 1, comprising a dimer acid-based polyamide resin having an amine value of 5 to 20 mgKOH / g. The polyamide resin aqueous dispersion according to claim 1 or 2, wherein the polyamide resin in the aqueous dispersion has a number average particle diameter of less than 0.5 µm. pH is 5-7, The polyamide resin aqueous dispersion in any one of Claims 1-3 characterized by the above-mentioned.   The aqueous dispersion of polyamide resin according to claim 1, wherein the aqueous medium contains a hydrophilic organic solvent. The method for producing a polyamide resin aqueous dispersion according to claim 1, wherein the dimer acid polyamide resin, lactic acid, and the aqueous medium are heated and stirred at 70 to 280 ° C.