JP2012158642A - Method for producing aqueous polyurethane resin dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an aqueous polyurethane resin dispersion, having a narrow molecular weight distribution, using no organic solvent during dispersion of water, and excellent in physical properties of a dry film thereof, and to provide an aqueous polyurethane resin dispersion obtained by the production method.SOLUTION: The method for producing an aqueous polyurethane resin dispersion (Q), which contains polyurethane resin particles (U1) having a volume average particle diameter of 0.005-5 μm, is characterized in that a polyurethane resin (U) having a terminal isocyanate group content of ≤0.2 mmol/g obtained without using an organic solvent is swollen with water at a temperature less than a melting temperature of the polyurethane resin (U), and then is dispersed in water at a temperature less than the melting temperature of the polyurethane resin (U) using a static type mixer (A) as a dispersing device.

Description

  The present invention relates to a method for producing an aqueous polyurethane resin dispersion and an aqueous polyurethane resin dispersion obtained by the production method.

Polyurethane resin aqueous dispersions are used in the paint, adhesive, binder and coating agent fields as highly functional aqueous dispersions due to their excellent durability, chemical resistance, abrasion resistance and other performances. However, it is thought that the importance will increase more from the viewpoints of environmental conservation, resource saving, safety, etc. The polyurethane resin aqueous dispersion may be produced by dispersing an isocyanate group-terminated urethane prepolymer in water and extending the chain with a diamine or the like (so-called prepolymer mixing method) (Patent Documents 1 to 3) and an isocyanate group. There is a method in which a polyurethane resin (dead polymer) which is hardly contained is dispersed in water.
Among these, since the former is chain-extended in water at the same time as dispersion (if necessary, after that), the molecular weight distribution of the resulting polyurethane resin tends to be widened, and as a result, the physical properties of the dry film are not sufficient. There was a point. On the other hand, the latter has a relatively narrow molecular weight distribution, but the dead polymer generally has a higher average molecular weight and a higher melting temperature (usually 80 to 300 ° C.) than the prepolymer. It was necessary to reduce the melt viscosity and disperse it in an aqueous medium at as low a temperature as possible. However, the use of organic solvents has environmental problems and safety problems for the human body. As a countermeasure, there has been proposed a method of dispersing a dead polymer in water without using an organic solvent or in the presence of a small amount of an organic solvent (Patent Document 4). This method is a method in which a polyurethane resin is dispersed in contact with an aqueous medium while being melted at a temperature equal to or higher than its melting temperature (usually 80 to 300 ° C.) with a melt extruder or the like. However, even in this method, there is a problem that the physical properties of the dry film of the aqueous dispersion obtained are lower than the physical properties of the dry film obtained directly from the dead polymer.

Japanese Patent Laid-Open No. 2004-2732 JP 2004-59676 A JP 2004-307721 A JP 2005-232277 A

  An object of the present invention is to produce a polyurethane resin aqueous dispersion that has a narrow molecular weight distribution, does not use an organic solvent during water dispersion, and has excellent physical properties of a dry film, and an aqueous polyurethane resin dispersion obtained by the production method To provide a body.

As a result of intensive studies, the present inventors have found a method for producing a polyurethane resin aqueous dispersion that can solve the above-described problems. That is, the present invention uses a polyurethane resin (U) having a terminal isocyanate group content of 0.2 mmol / g or less obtained without using an organic solvent at a temperature lower than the melting temperature of the polyurethane resin (U). And then swelled in water using a static mixer (A) as a dispersing device and dispersed in water at a temperature lower than the melting temperature of the polyurethane resin (U), and having a volume average particle size of 0.005 to 5 μm A polyurethane resin aqueous dispersion (Q) containing polyurethane resin particles (U1) and a polyurethane resin particle (U1) obtained by the production method and satisfying all of the following (1) to (3) A polyurethane resin aqueous dispersion.
(1) The weight average molecular weight / number average molecular weight (Mw / Mn) of the polyurethane resin particles (U1) is 1.5 to 3.5.
(2) The volume average particle diameter (Dv) of the polyurethane resin particles (U1) is 0.005 to 5 μm.
(3) Volume average particle diameter / number average particle diameter (Dv / Dn) of the polyurethane resin particles (U1) is 1.2 to 5.

The method for producing an aqueous polyurethane resin dispersion of the present invention has the following characteristics.
(1) An aqueous dispersion of a polyurethane resin having a very narrow molecular weight distribution can be obtained.
(2) Since no organic solvent is used, it is excellent in low environmental load, safety and low odor.
(3) An aqueous dispersion excellent in dispersion stability can be obtained.
(4) An aqueous dispersion in which the physical properties of the dry film are very excellent can be obtained.

  The production method of the present invention does not use an organic solvent in the process of producing the polyurethane resin (U) and the process of dispersing the (U) in water. Therefore, the polyurethane resin aqueous dispersion obtained by the production method of the present invention contains substantially no organic solvent.

  The polyurethane resin (U) in the present invention has a terminal isocyanate group content of 0.2 mmol / g or less based on the weight of the polyurethane resin (U), preferably 0.1 mmol / g or less, more preferably 0.8. 05 mmol / g or less, most preferably 0 mmol / g. By using such a so-called dead polymer, it is not necessary to carry out an elongation reaction in a dispersion system as in the conventional prepolymer mixing method, so that an aqueous polyurethane resin dispersion having a very narrow molecular weight distribution can be produced.

  In the production method of the present invention, in the process of dispersing the polyurethane resin (U), which is a dispersion, in the aqueous dispersion medium, the static mixer (A) is used as a dispersing device and the temperature is lower than the melting temperature of the resin. Disperse at temperature. When the resin is dispersed while being melted at a temperature equal to or higher than the melting temperature, the polyurethane resin and water are decomposed or deteriorated by contact at a high temperature, and as a result, the physical properties of the dry film are lower than expected. On the other hand, in the production method of the present invention, since the resin is dispersed at a temperature lower than the melting temperature of the resin, it is possible to disperse the target fine particles without melting the resin. A polyurethane resin aqueous dispersion which is not easily deteriorated and has excellent physical properties when formed into a dry film can be produced.

  The melting temperature of the polyurethane resin (U) in the present invention is preferably 70 to 280 ° C, more preferably 100 to 220 ° C, and most preferably 130 to 200 ° C, from the viewpoint of the resin physical properties of the dry film of the polyurethane resin aqueous dispersion. It is. The melting temperature in the present invention is JIS K7210 (plastic-thermoplastic melt mass flow rate test method) using a “melt indexer type I” (manufactured by Tester Sangyo Co., Ltd.) as a melt mass flow rate measuring device. The temperature at which the melt mass flow becomes 10 g / 10 min at a load of 2.16 kg.

  The polyurethane resin (U) in the present invention comprises the polyol (a), the polyisocyanate (b) and the compound (c) containing a hydrophilic group and an active hydrogen atom-containing group as essential components, and if necessary, a chain extender ( d), produced using a reaction terminator (e) and other components (f).

  The polyol (a) includes a high molecular polyol (a1) having a hydroxyl group equivalent (number average molecular weight per hydroxyl group, calculated from the number average molecular weight and hydroxyl value) of 150 or more, and a low molecular polyol (a2) having a hydroxyl group equivalent of less than 150. ). In the present invention, the number average molecular weight (hereinafter sometimes abbreviated as Mn) of the polyol is measured by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent and polyethylene glycol as a standard. Is. However, the number average molecular weight of the low molecular polyol is a calculated value from the chemical formula.

  Examples of the polymer polyol (a1) having a hydroxyl equivalent weight of 150 or more include polyether polyol (a11) and polyester polyol (a12).

  Examples of the polyether polyol (a11) include aliphatic polyether polyols and aromatic ring-containing polyether polyols.

  Examples of the aliphatic polyether polyol include polyoxyethylene polyol [polyethylene glycol (hereinafter abbreviated as PEG) and the like], polyoxypropylene polyol [polypropylene glycol (hereinafter abbreviated as PPG) and the like], polyoxyethylene / propylene polyol and Examples include polytetramethylene ether glycol.

  Examples of the aromatic polyether polyol include a polyol (a121) having a bisphenol skeleton, for example, an ethylene oxide (hereinafter abbreviated as EO) adduct of bisphenol A [EO 2 mol adduct of bisphenol A, EO 4 mol adduct of bisphenol A, bisphenol. EO 6 mol adduct of bisphenol A, EO 8 mol adduct of bisphenol A, EO 10 mol adduct of bisphenol A, EO 20 mol adduct of bisphenol A, etc.] and propylene oxide (hereinafter abbreviated as PO) adduct of bisphenol A [bisphenol A PO2 mol adduct of bisphenol A, PO3 mol adduct of bisphenol A, PO5 mol adduct of bisphenol A, etc.] and EO or PO adduct (a122) of resorcin.

  Polyether polyol (a11) is a ring-opening addition of EO or PO to an aliphatic or aromatic low molecular weight active hydrogen atom-containing compound in the presence of an addition catalyst (a known catalyst such as an alkali metal hydroxide and a Lewis acid). It is obtained by reacting.

  Mn of (a11) is usually 300 or more, preferably 300 to 10,000, more preferably 300 to 6,000. The hydroxyl group equivalent of (a11) is usually 150 or more, preferably 150 to 5,000, more preferably 150 to 3,000.

  Examples of the polyester polyol (a12) include condensed polyester, polylactone polyol, polycarbonate polyol, and castor oil-based polyol.

The condensed polyester is a polyester of a low molecular weight (Mn 300 or less) polyhydric alcohol and a polyvalent carboxylic acid or an ester-forming derivative thereof.
Low molecular weight polyhydric alcohols include dihydric to octavalent or higher aliphatic polyhydric alcohols having a hydroxyl group equivalent of 30 to less than 150 and dihydric to octavalent or higher phenols having a hydroxyl group equivalent of 30 to less than 150. AO low molar adducts can be used.
Among the low molecular weight polyhydric alcohols that can be used in the condensed polyester, ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexane glycol, EO or PO low molarity of bisphenol A are preferred. Adducts and combinations thereof.

  Examples of polyvalent carboxylic acids or ester-forming derivatives thereof that can be used in the condensed polyester include aliphatic dicarboxylic acids (succinic acid, adipic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, etc.), alicyclic dicarboxylic acids ( Dimer acids, etc.), aromatic dicarboxylic acids (terephthalic acid, isophthalic acid, phthalic acid, etc.) and trivalent or higher polycarboxylic acids (trimellitic acid, pyromellitic acid, etc.), and their anhydrides (succinic anhydride, Maleic anhydride, phthalic anhydride, trimellitic anhydride, etc.), their acid halides (such as adipic acid dichloride), their low molecular weight alkyl esters (such as dimethyl succinate and dimethyl phthalate), and combinations thereof. .

  Examples of the condensed polyester include polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyhexamethylene isophthalate diol, polyneopentyl adipate diol, polyethylene propylene adipate diol, polyethylene butylene adipate diol, polybutylene hexamethylene adipate Diol, polydiethylene adipate diol, poly (polytetramethylene ether) adipate diol, poly (3-methylpentylene adipate) diol, polyethylene azelate diol, polyethylene sebacate diol, polybutylene azelate diol, polybutylene sebacate diol and Examples include polyneopentyl terephthalate diol.

The polylactone polyol is a polyadduct of lactone to the low molecular weight polyhydric alcohol. As the lactone, a lactone having 4 to 12 carbon atoms can be used, for example, γ-butyrolactone, γ-valerolactone, ε-caprolactone, etc. Is mentioned.
Examples of the polylactone polyol include polycaprolactone diol, polyvalerolactone diol, and polycaprolactone triol.

The polycarbonate polyol is a polyaddition product of an alkylene carbonate to a low molecular weight polyhydric alcohol. As the alkylene carbonate, an alkylene carbonate having 2 to 8 carbon atoms can be used, and examples thereof include ethylene carbonate and propylene carbonate. Two or more of these may be used in combination.
Examples of the polycarbonate polyol include polyhexamethylene carbonate diol.
Examples of commercially available polycarbonate polyols include NIPPOLAN 980R [Mn = 2,000, manufactured by Nippon Polyurethane Industry Co., Ltd.], T5652 [Mn = 2,000, manufactured by Asahi Kasei Co., Ltd.], and T4672 [Mn = 2,000, Asahi Kasei. Made by Co., Ltd.].

  The castor oil-based polyol includes castor oil and castor oil modified with polyol or AO. Modified castor oil can be produced by transesterification of castor oil and polyol and / or AO addition. Castor oil-based polyols include castor oil, trimethylolpropane-modified castor oil, pentaerythritol-modified castor oil, and EO (4 to 30 mol) adduct of castor oil.

  Of the polyester polyol (a12), preferred are a condensed polyester and a polycarbonate polyol from the viewpoint of the resin physical properties of the polyurethane resin (U).

  Examples of the low molecular polyol (a2) having a hydroxyl group equivalent of less than 150 include aliphatic dihydric alcohols, aliphatic trihydric alcohols, and aliphatic tetrahydric or higher alcohols. Of these, (a2) is preferably a dihydric or trivalent aliphatic alcohol from the viewpoint of water resistance and heat-resistant yellowing, and examples of the aliphatic dihydric alcohol include ethylene glycol, propylene glycol, 1,4-butanediol, Neopentyl glycol and 1,6-hexanediol are particularly preferred, and trimethylolpropane is particularly preferred as the aliphatic trihydric alcohol.

  As the polyisocyanate (b) which is an essential constituent component of the polyurethane resin (U), those conventionally used for the production of polyurethane resins can be used. The polyisocyanate (b) is an aromatic polyisocyanate (b1) having 2 to 3 or more isocyanate groups and having 6 to 20 carbon atoms (excluding carbon in the isocyanate group, the same shall apply hereinafter), and 2 to 2 carbon atoms. 18 aliphatic polyisocyanate (b2), alicyclic polyisocyanate (b3) having 4 to 15 carbon atoms, and araliphatic polyisocyanate (b4) having 8 to 15 carbon atoms.

  Examples of the aromatic polyisocyanate (b1) include 1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate (TDI), 4,4′- or 2,4′-. Diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate, 4,4 ′, 4 ″ -triphenylmethane triisocyanate, m- or p-isocyanatophenylsulfonyl isocyanate.

  Examples of the aliphatic polyisocyanate (b2) include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, and 2-isocyanatoethyl-2. , 6-diisocyanatohexanoate.

  Examples of the alicyclic polyisocyanate (b3) include isophorone diisocyanate (IPDI), 4,4-dicyclohexylmethane diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexyl diisocyanate (hydrogenated TDI), and bis (2-isocyanate). Natoethyl) -4-cyclohexene-1,2-dicarboxylate and 2,5- or 2,6-norbornane diisocyanate.

  Examples of the araliphatic polyisocyanate (b4) include m- or p-xylylene diisocyanate (XDI) and α, α, α ', α'-tetramethylxylylene diisocyanate (TMXDI).

  Among the polyisocyanates (b), (b2) and (b3) are preferable from the viewpoint of the resin physical properties of the polyurethane resin (U), (b3) is more preferable, and IPDI and hydrogenated MDI are particularly preferable. .

  The polyurethane resin (U) needs to contain a structural unit containing a hydrophilic group from the viewpoint of dispersion stability, and the content of the hydrophilic group is 5% by weight based on the weight of the polyurethane resin (U). The following is preferable, and more preferably 0.5 to 3% by weight. If it is 5% by weight or less, the water resistance of the formed film is less likely to decrease, which is preferable. In order to introduce a hydrophilic group into the polyurethane resin (U), a method of using the compound (c) containing a hydrophilic group and an active hydrogen atom-containing group as one component of the raw material can be mentioned. The compound (c) has a hydrophilic group for stably dispersing the polyurethane resin (U) in water, and is incorporated into the molecular chain of the polyurethane resin by reaction with the polyisocyanate (b). A compound having one active hydrogen atom-containing group per molecule, preferably 2 to 3 is preferred.

The amount of (c) used is preferably such that the content of the hydrophilic group based on the weight of the polyurethane resin (U) is 5% by weight or less, more preferably 0.5 to 3.0% by weight. Is the amount used.

Examples of the compound (c) containing a hydrophilic group and an active hydrogen atom-containing group include an anionic group-containing active hydrogen-containing component (c1) and a cationic group-containing active hydrogen-containing component (c2).
Examples of (c1) include those having a carboxyl group as a hydrophilic group [dialkylol alkanoic acid (for example, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylolheptanoic acid) And 2,2-dimethyloloctanoic acid), tartaric acid, amino acids (for example, glycine, alanine, and valine)], those containing a sulfonic acid group as a hydrophilic group [3- (2,3-dihydroxypropoxy) -1-propane Sulfonic acid and sulfoisophthalic acid di (ethylene glycol) ester, etc.], those containing a sulfamic acid group as a hydrophilic group [N, N-bis (2-hydroxylethyl) sulfamic acid, etc.], and salts thereof.

Examples of the salts of (c1) include neutralized salts with neutralizing agents such as ammonia, amine compounds having 1 to 10 carbon atoms, and / or alkali metals (sodium, potassium, lithium, etc.).
Examples of the amine compound having 1 to 10 carbon atoms include primary amines such as monomethylamine, monoethylamine, monobutylamine and monoethanolamine, secondary amines such as dimethylamine, diethylamine, dibutylamine and diethanolamine, trimethylamine, triethylamine and dimethylethylamine. And tertiary amines such as triethanolamine.
As the compound that forms the salt of (c1), a compound having a high vapor pressure at 25 ° C. is preferable from the viewpoint of the drying property of the aqueous polyurethane resin dispersion to be formed and the water resistance after drying. From such a viewpoint, ammonia and an amine compound having 1 to 10 carbon atoms are preferable, and ammonia, monomethylamine, monoethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine and dimethylethylamine are more preferable, and ammonia, monomethylamine are particularly preferable. Ethylamine, dimethylamine and diethylamine, most preferred is ammonia.

  Among (c1), preferred are 2,2-dimethylolpropionic acid and 2,2-dimethylol from the viewpoints of the resin properties of the polyurethane resin (U) and the dispersion stability of the polyurethane resin aqueous dispersion (Q). Butanoic acid and salts thereof are more preferably neutralized salts of 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid with ammonia or an amine compound having 1 to 10 carbon atoms.

  (C2) is, for example, a tertiary amino group-containing diol having 3 to 20 carbon atoms [N-alkyl dialkanolamine (for example, N-methyldiethanolamine, N-propyldiethanolamine, N-butyldiethanolamine and N-methyldipropanolamine) and N, N-dialkylalkanolamine (for example, N, N-dimethylethanolamine)] and salts thereof.

Examples of the salts of (c2) include neutralized salts with neutralizing agents such as monocarboxylic acids having 1 to 20 carbon atoms (such as formic acid, acetic acid and propanoic acid), and 4 such as dimethyl sulfate, dimethyl carbonate, methyl chloride and benzyl chloride. A quaternary salt by a classifying agent can be mentioned.
As the neutralizing agent of (c2), a compound having a high vapor pressure at 25 ° C. is preferable from the viewpoint of the drying property of the aqueous dispersion of the polyurethane resin to be produced and the water resistance after drying. From such a viewpoint, the neutralizing agent (c2) is preferably a monocarboxylic acid having 1 to 10 carbon atoms (for example, acetic acid and propanoic acid), and particularly preferably formic acid.

  As the structural unit containing a hydrophilic group in the polyurethane resin (U), from the viewpoint of the balance between the dispersibility of the aqueous dispersion of the generated polyurethane resin and the water resistance of the film after drying, the polyurethane resin (U) A structural unit obtained by neutralizing an anionic group in the skeleton with ammonia or an amine compound having 1 to 10 carbon atoms, or a structural unit obtained by neutralizing a cationic group in the skeleton with a monocarboxylic acid having 1 to 10 carbon atoms. Is preferred.

  The chain extender (d) used as necessary in the production of (U) of the present invention includes water, diamines having 2 to 10 carbon atoms (for example, ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, toluene). Diamines and piperazines), polyalkylene polyamines (for example, diethylenetriamine and triethylenetetramine), hydrazine or derivatives thereof (for example, dibasic acid dihydrazides such as adipic acid dihydrazide) and C2-C10 amino alcohols (for example, ethanolamine, diethanolamine). , 2-amino-2-methylpropanol, triethanolamine, etc.).

  As the reaction terminator (e) used as necessary in the production of (U), monoalcohols having 1 to 8 carbon atoms (methanol, ethanol, isopropanol, cellosolves, carbitols, etc.), carbon number 1 To 10 monoamines (mono- or dialkylamines such as monomethylamine, monoethylamine, monobutylamine, dibutylamine and monooctylamine; mono- or dialkanolamines such as monoethanolamine, diethanolamine and diisopropanolamine).

  Examples of the other component (f) used as necessary in the production of (U) include a crosslinking agent, a catalyst, an antioxidant, a coloring inhibitor, a retarder, a plasticizer, and a release agent.

  The polyurethane resin (U) in the present invention is obtained by urethanation in the absence of an organic solvent, preferably at 100 to 250 ° C., more preferably at 150 to 250 ° C., particularly preferably at 180 to 220 ° C. It is preferable that it is the polyurethane resin obtained. In the polyurethane resin (U) in the present invention, examples of the method for setting the terminal isocyanate group content to 0.2 mmol / g or less include the following methods (1) to (3).

(1) The equivalents of hydroxyl groups and amino groups are 0.9 times or more (preferably 1 time or more) with respect to the number of equivalents of isocyanate groups in the raw material.
(2) A reaction terminator (e) and / or water is added to react and consume isocyanate groups.
(3) A burette bond and / or an allophanate bond are generated by a high temperature reaction (for example, 150 to 250 ° C.), and the isocyanate group is consumed.

  Generally, a polyurethane resin has a urethane group derived from a reaction between an isocyanate group and a hydroxyl group, and a urea group derived from a reaction between the isocyanate group and an amino group (or water). Due to the high hydrophilicity, polyurethane resins having a high urea group content tend to have poor film-forming properties and water resistance.

  In the polyurethane resin (U) in the present invention, a urea group derived from a reaction between an isocyanate group and a raw material having an amino group, water contained in the raw material and / or water of the medium at the time of dispersion in water, and an isocyanate group may be generated. From the viewpoint of film-forming properties and water resistance, the urea group content is preferably 0.1 mmol / g or less, more preferably 0.05 mmol / g or less, particularly preferably 0.03 mmol / g or less, most preferably 0.01 mmol. / G or less.

  In the polyurethane resin (U) in the present invention, examples of the method for setting the urea group content to 0.1 mmol / g or less include the following methods (1) to (3).

(1) The content of amino groups in the raw material of the polyurethane resin (U) is 0.1 mmol / g or less.
(2) The water content in the raw material of the polyurethane resin (U) is adjusted to 0.1 mmol / g or less.
(3) The isocyanate group content of the polyurethane resin (U) is 0.2 mmol / g or less.

  Mn of polyurethane resin (U) in the present invention [measured by GPC using dimethylformamide (hereinafter abbreviated as DMF) as a solvent and based on standard polystyrene] is a non-crosslinked type (thermoplastic: crosslinker). In the case of a type that does not use), it is usually 2,000 to 2,000,000 or more, preferably 5,000 to 500,000, and more preferably 10,000 to 100,000. (U) of a crosslinking type (a type using a crosslinking agent) may have a Mn higher than the above range or a high Mn that cannot be measured by GPC.

  The reaction vessel for performing the urethanization reaction can be used without any problem as long as it can be heated and stirred, but from the viewpoint of stirring strength, hermeticity and heating ability, a uniaxial or biaxial kneader is used. preferable. Examples of the uniaxial or biaxial kneader include a continuous kneader [manufactured by Kurimoto Seiko Co., Ltd.] and PCM30 [manufactured by Ikegai Co., Ltd.]. The polyurethane resin (U) in the present invention is preferably a polyurethane resin obtained by a urethanization reaction at 150 to 250 ° C. in a uniaxial or biaxial kneader from the viewpoint of the urethanization reaction rate and mixing properties.

  Hereinafter, the present invention will be described in more detail by showing a method for producing a polyurethane resin aqueous dispersion comprising a polyurethane resin (U1) in which a polyurethane resin (U) is dispersed in water.

  In the method for producing an aqueous polyurethane dispersion of the present invention, the above-mentioned polyurethane resin (U) is dispersed in water at a temperature lower than the melting temperature of the polyurethane resin (U) using a static mixer (A) as a dispersing device. This is a method for producing an aqueous polyurethane resin dispersion (Q) containing polyurethane resin particles (U1) having a volume average particle diameter of 0.005 to 5 μm.

  The polyurethane resin (U) after the urethanization reaction has a melting temperature of 70 to 280 ° C., is usually solid at room temperature, and the particle size is preferably 0.2 to 200 mm, more preferably 0.2. From the viewpoint of ease of processing in the static mixer (A), a particle size of ˜50 mm, particularly preferably 0.2 to 10 mm is preferable.

As means for granulating the polyurethane resin (U), means such as cutting, pelletizing, granulating, or pulverizing can be used. This granulation can be carried out in water or in the absence of water.
For example, the polyurethane resin (U) rolled into a sheet shape is cut into a strip shape with a strand cutter and then granulated with a rotary blade.

  The polyurethane resin (U) adjusted to be granular is swollen with water while neutralizing as necessary, and then introduced into the static mixer (A). The main dispersion principle of (A) is According to the provided structure, the processed product is divided, converted, and inverted to be mixed and stirred.

  The swelling of the polyurethane resin (U) with water is less than the melting temperature of the polyurethane resin (U), preferably 5 ° C. or more lower than the melting temperature, from the viewpoint of preventing decomposition or deterioration of the polyurethane resin (U) as a dispersion. It is preferable that the temperature is higher than room temperature, more preferably 10 to 120 ° C. lower than the melting temperature.

  Examples of the static mixer (A) include a static mixer (manufactured by Noritake Company).

  The temperature of the dispersion liquid when the polyurethane resin (U) is dispersed using the static mixer (A) is selected from the viewpoint of preventing decomposition and deterioration of the polyurethane resin (U) as a dispersion. It is preferable that the temperature is lower than the melting temperature, preferably 5 ° C. or more lower than the melting temperature and higher than room temperature, more preferably 10 to 120 ° C. lower than the melting temperature and higher than room temperature.

  The weight ratio of the polyurethane resin (U) and water supplied to the static mixer (A) is appropriately selected depending on the resin component content of the target aqueous dispersion. Usually, (U) / water = 10/2 to 10/100, preferably 10/5 to 10/50.

  The volume average particle diameter (Dv) of the polyurethane resin particles (U1) in the polyurethane resin aqueous dispersion (Q) obtained by the above method is usually 0.005 to 5 μm, but the dispersion stability of (Q) From the viewpoint of improvement, it is preferably 0.005 to 4 μm, more preferably 0.02 to 2 μm, particularly preferably 0.03 to 1 μm, and most preferably 0.03 to 0.8 μm.

  The volume average particle diameter (Dv) of the polyurethane resin particles (U1) in the present invention is determined by a laser diffraction particle size distribution measuring device [for example, LA-750 {manufactured by Horiba, Ltd.}] or a light scattering particle size distribution measuring device [ For example, it can be measured using ELS-8000 {manufactured by Otsuka Electronics Co., Ltd.}]. The number average particle diameter (Dn) described later can also be measured by the same measurement method.

  When dispersing in the static mixer (A), if necessary, one or more selected from pH adjusters, antifoaming agents, anti-coloring agents, plasticizers, mold release agents, etc. are added. can do. Moreover, you may concentrate or dilute after dispersion | distribution as needed.

  Since the polyurethane resin aqueous dispersion (Q) obtained by the production method of the present invention does not substantially use an organic solvent in the production process, the remaining organic solvent is substantially absent.

  The solid content concentration (content of components other than water) of the polyurethane resin aqueous dispersion (Q) obtained by the production method of the present invention is preferably 20 to 65% by weight, more preferably 25 to 55% by weight. The solid concentration was about 1 g of the aqueous dispersion thinly spread on a Petri dish, weighed accurately, then weighed the weight after heating at 130 ° C for 45 minutes using a circulating constant temperature drier, before heating. It can be obtained by calculating the ratio (percentage) of the remaining weight after heating to the weight.

The viscosity of the polyurethane resin aqueous dispersion (Q) obtained by the production method of the present invention is preferably 10 to 100,000 mpa · s, more preferably 10 to 5,000 mpa · s, from the viewpoint of operability during use. is there. The viscosity can be measured at a constant temperature of 25 ° C. using a B-type rotational viscometer.
The pH of the polyurethane resin aqueous dispersion (Q) obtained by the production method of the present invention is preferably 2 to 12, more preferably 4 to 10, from the viewpoint of storage stability. The pH can be measured at 25 ° C. with pHMeter M-12 [manufactured by Horiba, Ltd.].

The polyurethane resin aqueous dispersion (Q) obtained by the production method of the present invention is usually a polyurethane resin aqueous dispersion containing polyurethane resin particles (U1) that satisfy all of the following (1) to (3).
(1) The weight average molecular weight / number average molecular weight (hereinafter abbreviated as Mw / Mn) of the polyurethane resin particles (U1) is 1.5 to 3.5.
(2) The volume average particle diameter (Dv) of the polyurethane resin particles (U1) is 0.005 to 5 μm.
(3) Volume average particle diameter / number average particle diameter (Dv / Dn) of the polyurethane resin particles (U1) is 1.2 to 5.
The aqueous polyurethane resin dispersion of the present invention is particularly excellent in dispersion stability and resin physical properties after drying.

Mw / Mn of the polyurethane resin (U1) of (1) is preferably 1.5 to 3, and more preferably 1.5 to 2.5. If Mw / Mn is within this range, the molecular weight distribution is narrow, so that the resin physical properties after drying and the film-forming properties during drying are further improved. The Mw and Mn of the polyurethane resin (U1) are measured by GPC using DMF as a solvent and standard polystyrene.
Dv of the polyurethane resin (U1) of (2) is preferably 0.005 to 4 μm, more preferably 0.02 to 2 μm, particularly preferably 0.03 to 1 μm, most preferably from the viewpoint of improving dispersion stability. Is 0.03 to 0.8 μm.
The Dv / Dn of the polyurethane resin (U1) of (3) is preferably 1.2 to 4, more preferably 1.2 to 3. If Dv / Dn is within this range, the dispersion stability and the film-forming property during drying are further improved.

  The polyurethane resin aqueous dispersion of the present invention comprises a coating composition, an adhesive composition, a binder composition for fiber processing (a binder composition for pigment printing, a binder composition for nonwoven fabric, a sizing agent composition for reinforcing fibers, and an antibacterial agent). Binder composition, etc.), coating compositions (waterproof coating compositions, water repellent coating compositions, antifouling coating compositions, etc.), and artificial leather / synthetic leather raw material compositions.

  If necessary, the coating composition may contain other additives such as coating film forming auxiliary resins, crosslinking agents, pigments, pigment dispersants, viscosity modifiers, antifoaming agents, leveling agents, preservatives, deterioration inhibitors, stabilizers. And 1 type (s) or 2 or more types, such as an antifreezing agent, can be added.

  When used as a binder composition for an antibacterial agent, a coating composition, and a raw material composition for artificial leather / synthetic leather, the additive, the concentration of the treatment liquid, the means for application to the fiber, the amount of adhesion to the fiber and the treatment conditions are It can be appropriately selected depending on the application.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these. Hereinafter, “part” means “part by weight” and “%” means “% by weight”.

  As described above, the melting temperature is measured in accordance with JIS K7210 (Testing method for melt mass flow rate of plastic-thermoplastic plastic) and using “melt indexer type I” (manufactured by Tester Sangyo Co., Ltd.) The temperature at which the melt mass flow was 10 g / 10 min at 2.16 kg was taken as the melting temperature.

Example 1
To a KRC kneader [manufactured by Kurimoto Seiko Co., Ltd.] of a biaxial kneader, a polycarbonate diol having an Mn of 1,000 “Asahi Kasei PCDL-T4671” [manufactured by Asahi Kasei Chemicals] 189.0 parts, 2,2-di 21.5 parts of methylolpropionic acid (hereinafter abbreviated as DMPA) and 90.2 parts of 4,4-dicyclohexylmethane diisocyanate (hereinafter abbreviated as hydrogenated MDI) were introduced under a nitrogen atmosphere. Thereafter, the mixture was heated to 220 ° C. and kneaded for 10 minutes to conduct a urethanization reaction. The reaction product was taken out, rolled with a pressure press machine heated to 180 ° C., and then cut with a square pellet machine (manufactured by Horai Co., Ltd.) to obtain a polyurethane resin (U-1). Subsequently, 300.7 parts of the cut polyurethane resin (U-1), 688.4 parts of 90 ° C. ion-exchanged water and 10.9 parts of 25% aqueous ammonia (neutralizing agent) were mixed, and the mixture was stirred at 90 ° C. for 10 minutes. After swelling (U-1) with neutralized and ion-exchanged water, it was dispersed with a static mixer (manufactured by Noritake Company: 16 elements) under a condition of 120 ° C. to obtain a polyurethane resin aqueous dispersion (Q-1). ) 1,000 parts were obtained. Table 1 shows conditions, analysis values, and the like in each step.

Comparative Example 1
In a simple pressure reactor equipped with a stirrer and a heater, a polycarbonate diol having an Mn of 2,000 "Asahi Kasei PCDL-T4672" [Asahi Kasei Chemicals Co., Ltd.] 183.8 parts, DMPA 21.8 parts, hydrogenated MDI100 0.0 part and 204.1 parts of acetone were charged while introducing nitrogen. Thereafter, the mixture was heated to 85 ° C. and subjected to urethanization reaction for 10 hours to produce a prepolymer. The isocyanate content of the resin solid content at the end of the urethanization reaction was 0.83 mmol / g. After cooling the reaction mixture to 40 ° C., 16.4 parts of triethylamine (neutralizing agent) and 683.6 parts of water were added while stirring in a simple pressure reactor. Subsequently, acetone was removed under reduced pressure at 65 ° C. over 8 hours to obtain 1,000 parts of a polyurethane resin aqueous dispersion. Table 1 shows conditions, analysis values, and the like in each step. The NCO content of (U) in Comparative Example 1 in Table 1 indicates the isocyanate content of the prepolymer, and the melting temperature of (U) is the melting temperature of the dried polyurethane resin aqueous dispersion finally obtained. Indicates.

Table 1 shows physical property values of the aqueous dispersion obtained above, measured by the following measurement methods.
<Mw and Mn>
The aqueous dispersion was added to DMF so that the solid content of the polyurethane resin was 0.0125% by weight, stirred at room temperature for 1 hour, and then filtered under pressure with a filter having a pore size of 0.3 μm, and the resulting filtrate was obtained. The urethane resin contained in was measured by GPC using DMF as a solvent and polystyrene as a molecular weight standard.
<Dv and Dn>
After diluting the polyurethane resin aqueous dispersion with ion-exchanged water so that the solid content of the polyurethane resin is 0.01% by weight, a light scattering particle size distribution analyzer [ELS-8000 {manufactured by Otsuka Electronics Co., Ltd.}] is used. Measured.
<Odor of dispersion>
The solvent odor of the polyurethane resin aqueous dispersion adjusted to 25 ° C. was subjected to sensory evaluation. When the solvent odor is not felt, it is marked as ◯, and when the solvent odor is felt, it is marked as x.
<Dispersion stability of dispersion>
The polyurethane resin aqueous dispersion whose temperature was adjusted to 25 ° C. was allowed to stand for 12 hours, and the occurrence of sediment was visually evaluated. The case where no sediment was generated was marked as ◯, and the case where sediment was generated was marked as x.

<Physical properties of dry film (100% stress, tensile strength and elongation at break)>
5. According to JIS K7311 Based on a tensile test. The measurement sample was uniformly mixed with 10 parts of a polyurethane resin aqueous dispersion and 1 part of N-methylpyrrolidone, and poured into a polypropylene mold having a size of 10 cm × 20 cm × 1 cm so that the film thickness after moisture drying was 200 μm. Based on the film obtained by heating and drying at 105 ° C. for 3 hours at room temperature for 12 hours at room temperature and based on the 5.1 test piece described in JIS K7311.
<Water resistance of dry film>
The film obtained in the same manner as the measurement of physical properties of the dried film was immersed in ion-exchanged water for 24 hours, and then the state of the film taken out was visually evaluated. When it did not change at all, ◎, when whitening was observed, ◯, when whitening did not remain the original, ×.
<Low temperature drying property of dispersion>
10 parts of polyurethane resin aqueous dispersion was poured into a 10 cm × 20 cm × 1 cm polypropylene mold in such an amount that the film thickness after drying with water was 200 μm, and it was determined whether or not the film was formed after drying at room temperature for 48 hours. . In the case of film formation, ◎, and in the case of no film formation, Δ.

  The aqueous polyurethane resin dispersion obtained by the production method of the present invention can be suitably used as a coating composition, an adhesive composition, and a binder for fiber processing.

Claims (8)

  After the polyurethane resin (U) having a terminal isocyanate group content of 0.2 mmol / g or less obtained without using an organic solvent is swollen with water at a temperature lower than the melting temperature of the polyurethane resin (U). The polyurethane resin particles (U1) having a volume average particle diameter of 0.005 to 5 μm, which are dispersed in water at a temperature lower than the melting temperature of the polyurethane resin (U) using a static mixer (A) as a dispersing device ) -Containing polyurethane resin aqueous dispersion (Q).   The method for producing an aqueous polyurethane resin dispersion according to claim 1, wherein the polyurethane resin (U) has a melting temperature of 70 to 280 ° C. and has a particle size of 0.2 to 200 mm.   The polyurethane resin water dispersion according to claim 1 or 2, wherein the polyurethane resin (U) is a polyurethane resin obtained by urethanating a polyol and a polyisocyanate at 100 to 250 ° C in a uniaxial or biaxial kneader. Body manufacturing method.   4. The polyurethane resin water according to claim 3, wherein, following the urethanization reaction, granulation to make the particle size of the polyurethane resin (U) 0.2 to 200 mm and production of the polyurethane resin water dispersion (Q) are continuously performed. A method for producing a dispersion.   The polyurethane resin (U) contains a structural unit containing a hydrophilic group, and the content of the hydrophilic group is 5% by weight or less based on the weight of the polyurethane resin (U). The manufacturing method of the polyurethane resin water dispersion in any one.   The structural unit containing the hydrophilic group is a structural unit or cationic group obtained by neutralizing an anionic group in the skeleton of the polyurethane resin (U) with ammonia or an amine compound having 1 to 10 carbon atoms. The process for producing an aqueous polyurethane resin dispersion according to claim 5, which is a structural unit neutralized with 10 monocarboxylic acids.   The method for producing an aqueous polyurethane resin dispersion according to any one of claims 1 to 6, wherein the content of urea groups contained in the polyurethane resin (U) is 0.1 mmol / g or less. A polyurethane resin aqueous dispersion containing polyurethane resin particles (U1) obtained by the production method according to claim 1 and satisfying all of the following (1) to (3).
(1) The weight average molecular weight / number average molecular weight (Mw / Mn) of the polyurethane resin particles (U1) is 1.5 to 3.5.
(2) The volume average particle diameter (Dv) of the polyurethane resin particles (U1) is 0.005 to 5 μm.
(3) Volume average particle diameter / number average particle diameter (Dv / Dn) of the polyurethane resin particles (U1) is 1.2 to 5.