JP2012172010A - Method for producing polyurethane resin water dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyurethane resin water dispersion having a narrow molecular weight distribution, using no organic solvents when dispersed in water, and giving dry films excellent in physical properties; and to provide a polyurethane resin water dispersion obtained by the production method.SOLUTION: There is provided a method for producing the polyurethane resin water dispersion (Q), which method comprises dissolving in supercritical state or subcritical state water (A) a polyurethane resin (U) provided by using no organic solvents and having a terminal isocyanate group content of ≤0.2 mmol/g, and then performing at least one operation of cooling and decompression to form polyurethane resin particles (U1) having volume-average particle diameter (Dv) of 0.005-5 μm.

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 as paints, adhesives, binders or coating agents in the field of paints, adhesives, binders, and coatings as highly functional aqueous dispersions due to their excellent durability, chemical resistance, and abrasion resistance. However, it is thought that the importance will increase more from the viewpoints of environmental conservation, resource saving, safety, etc. As a method for producing a polyurethane resin aqueous dispersion, a urethane prepolymer having an isocyanate group terminal is dispersed in water and chain-extended with diamine or the like (so-called prepolymer mixing method) (see, for example, Patent Documents 1 to 3) and an isocyanate group. There is a method in which a polyurethane resin (dead polymer) containing almost no 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, so that it is dissolved or plasticized with an organic solvent. Therefore, it has been necessary to disperse in an aqueous medium, and there have been environmental problems due to the use of organic solvents and safety problems for human bodies.

Japanese Patent Laid-Open No. 2004-2732 JP 2004-59676 A JP 2004-307721 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 dissolves a polyurethane resin (U) having a terminal isocyanate group content of 0.2 mmol / g or less obtained without using an organic solvent in water (A) in a supercritical state or a subcritical state. Then, a polyurethane resin aqueous dispersion (Q) characterized in that polyurethane resin particles (U1) having a volume average particle diameter (Dv) of 0.005 to 5 μm are formed by performing at least one of cooling and decompression. ) And a polyurethane resin aqueous dispersion containing the polyurethane resin particles (U1) obtained by the production method 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.

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.

It is the schematic of a manufacturing apparatus.

  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.

  Moreover, the terminal isocyanate group content of the polyurethane resin (U) in this invention is 0.2 mmol / g or less based on the weight of a polyurethane resin (U), Preferably it is 0.1 mmol / g or less, More preferably, it is 0.00. 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.

  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).

  Examples of the polyol (a) include a high molecular polyol (a1) having a hydroxyl group equivalent (number average molecular weight per hydroxyl group calculated from a hydroxyl value) of 150 or more and a low molecular polyol (a2) having a hydroxyl group equivalent of less than 150.

  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.

The number average molecular weight (hereinafter abbreviated as Mn) of (a11) is usually 300 or more, preferably 300 to 10,000, more preferably 300 to 6,000. The number average molecular weight of the polyol in the present invention is measured by gel permeation chromatography (hereinafter abbreviated as GPC) using tetrahydrofuran as a solvent and polyethylene glycol as a standard. However, Mn of the low molecular polyol is a calculated value from the chemical formula.
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.
Examples of the low molecular weight polyhydric alcohol include dihydric to octavalent or higher aliphatic polyhydric alcohol having a hydroxyl group equivalent of 30 to less than 150 and dihydric to octavalent or higher phenol 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, bisphenol A EO or PO low molar addition Products 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 be inferior in 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 resin dispersion according to the present invention, the polyurethane resin (U) is dissolved in water (A) in a supercritical state or a subcritical state, and then at least one of cooling and decompression is performed. Thus, the polyurethane resin aqueous dispersion (Q) is produced by forming polyurethane resin particles (U1) having a volume average particle diameter (Dv) 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 has a particle size of 0 from the viewpoint of ease of dissolution in (A). It is preferable that the particle size is 2 to 200 mm, and the particle size of (U) is more preferably 0.2 to 50 mm, and particularly preferably 0.2 to 10 mm.

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 supercritical water in the present invention means water under temperature / pressure conditions of a critical temperature (374 ° C.) or higher and a critical pressure (22 MPa) or higher, and subcritical water is 200 ° C. This means water that is under the temperature condition below the critical temperature. The temperature and pressure conditions of the supercritical or subcritical water (A) are preferably set within a range in which the polyurethane resin (U) is completely dissolved and the decomposition rate of the polyurethane resin (U) is not large. . The temperature is preferably 200 to 500 ° C, more preferably 250 to 400 ° C. The pressure is preferably 1.5 to 40 MPa, more preferably 3 to 30 MPa.
Supercritical or subcritical water (A) can be obtained by heating and pressurizing to the target temperature and pressure with an electric heater, magnetic induction heating device and microwave heating device, etc. You may pressurize.

By mixing and dissolving the polyurethane resin (U) in the supercritical or subcritical water (A), a supercritical or subcritical aqueous solution (B) in which the polyurethane resin (U) is dissolved is obtained. It is done.
Any method may be used for mixing (U) with (A), and examples thereof include the following methods.
(1) A method in which a dispersion in which polyurethane resin (U) is dispersed in water is prepared in advance, and this is mixed into supercritical or subcritical water (A) by a pump.
(2) A method in which the polyurethane resin (U) is mixed directly into (A) with a rotary valve or the like.
In the above method (1), in order to disperse the particles of the polyurethane resin (U) in water, the surfactant (S) and the polymer activity are within a range of addition amounts that do not deteriorate the productivity and increase the environmental load. An agent (T) or the like may be added. The surfactant (S) and the polymer surfactant (T) may be added in water, or may be previously contained in the polyurethane resin (U).

  As surfactant (S), anionic surfactant (S-1), cationic surfactant (S-2), amphoteric surfactant (S-3), nonionic surfactant (S-4), etc. Is mentioned. The surfactant (S) may be a combination of two or more surfactants. Examples of the anionic surfactant (S-1) include carboxylic acid or a salt thereof, a sulfate ester salt, a salt of carboxymethylated product, a sulfonate salt, and a phosphate ester salt. Examples of the cationic surfactant (S-2) include a quaternary ammonium salt type and an amine salt type. The amphoteric surfactant (S-3) used in the present invention includes a carboxylate type amphoteric surfactant, a sulfate ester type amphoteric surfactant, a sulfonate type amphoteric surfactant, and a phosphate ester type amphoteric interface. Examples of the surfactant include amphoteric surfactants and amino acid-type amphoteric surfactants and betaine-type amphoteric surfactants. Examples of the nonionic surfactant (S-4) include alkylene oxide addition type nonionic surfactants and polyhydric alcohol type nonionic surfactants.

  Examples of the polymeric active agent (T) include cellulose compounds (for example, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose and saponified products thereof), gelatin, starch, dextrin, gum arabic, Chitin, chitosan, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene glycol, polyethyleneimine, polyacrylamide, acrylic acid (salt) -containing polymer (sodium polyacrylate, potassium polyacrylate, ammonium polyacrylate, sodium hydroxide part of polyacrylic acid Neutralized product, sodium acrylate-acrylic acid ester copolymer), sodium hydroxide of styrene-maleic anhydride copolymer Partial) neutralization product, water-soluble polyurethane (polyethylene glycol, reaction products of polycaprolactone diol with polyisocyanate etc.) and the like.

  The polyurethane resin (U) is preferably dissolved quickly in (A), and a known dispersion mechanism can be used. Examples thereof include ultrasonic dispersion, stirring dispersion, and media dispersion. be able to. When the polyurethane resin (U) is dispersed in (A), the Reynolds number is preferably 500 or more, more preferably 1000 or more, and particularly preferably 2000 or more.

When the polyurethane resin (U) is completely dissolved in the supercritical or subcritical water (A), the dissolution time may be set within a range in which the molecular weight of the polyurethane resin (U) is not significantly reduced by decomposition. preferable. The same applies to the time until the time point at which at least one of cooling and decompression is performed after dissolution.
The weight average molecular weight (Mwi) of the polyurethane resin (U) before being dissolved in the supercritical or subcritical water (A), and the weight average molecular weight (Mwe) after performing at least one of cooling and decompression operations. ) From the viewpoint of the physical properties of the resin particle polyurethane resin (U), Mwe / Mwi is preferably 0.5 or more, more preferably 0.7 or more, and particularly preferably 0.9 or more.
In the present invention, the weight average molecular weight and number average molecular weight of the polyurethane resin are measured by GPC using dimethylformamide as a solvent and polystyrene as a standard.

  The aqueous solution (B) in the supercritical state or subcritical state in which the polyurethane resin (U) is dissolved is subjected to at least one of cooling and decompression, whereby (B) is released from the supercritical state or subcritical state, and the polyurethane resin (U) becomes supersaturated, polyurethane resin particles (U1) are precipitated, and a urethane resin aqueous dispersion (Q) is obtained. By such a method, an aqueous dispersion of a polyurethane resin having a narrow molecular weight distribution can be obtained without using an organic solvent.

The operation of cooling and decompression may be performed by cooling the container containing (B) or the pipe through which (B) flows with a refrigerant from the outside, and (B) is usually 0 to 90 ° C., preferably You may make it discharge in the normal pressure water and the air of the temperature of 0-50 degreeC. When cooling a container or piping, it is necessary to set the temperature of a refrigerant | coolant so that an inside may not become 0 degrees C or less, The temperature becomes like this. Preferably it is 0-100 degreeC, More preferably, it is 5-50 degreeC.
The method of discharging (B) is not particularly limited, and examples thereof include a method of spraying through a nozzle, capillary, orifice, or the like. When discharging (B), in order to suppress the aggregation of the precipitated resin particles, the surfactant (S), the polymer surfactant (T) and the like are previously discharged at a normal pressure at which (B) is discharged. It may be added to water.
The cooling rate is preferably set as appropriate according to the target particle size of the resin particles. Usually, the more rapidly the cooling is performed, the finer resin particles are obtained. The time for cooling from the dissolution temperature [temperature of (B)] of the polyurethane resin (U) to the temperature at which the polyurethane resin particles (U1) are precipitated is preferably 1 second to 30 minutes, more preferably 5 seconds to 15 minutes. .

  The apparatus for producing the resin water dispersion of the present invention may be any of batch, semi-batch, and continuous, but is preferably continuous from the viewpoint of productivity and continuously. Water dispersion of polyurethane resin (U) or (U) continuously in the supercritical or subcritical water (A), the part (X1) that heats and pressurizes water to make it supercritical or subcritical Part (X2) in which the body is mixed, part (X3) in which the polyurethane resin (U) is uniformly dissolved at a constant temperature and constant pressure in (A), and (B) in which (U) is dissolved in (A) It is preferable to have a portion (X4) for continuously performing at least one of cooling and decompression and a portion (X5) for storing the cooled and / or decompressed fluid. Here, it is preferable to hold (X2) and (X3) in a supercritical state or a subcritical state, and it is preferable to provide a pressure adjusting mechanism such as a pressure adjusting valve in (X4).

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

  When manufacturing a resin water dispersion, 1 or more types chosen from a pH adjuster, an antifoamer antioxidant, a coloring inhibitor, a plasticizer, a mold release agent, etc. can be added as needed. 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 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.
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 volume average particle diameter (Dv) and number average particle diameter (Dn) of the polyurethane resin particles (U1) in the present invention are measured by a laser diffraction particle size distribution measuring apparatus [for example, LA-750 {manufactured by Horiba, Ltd.}], Or it can measure using the light-scattering particle size distribution measuring apparatus [For example, ELS-8000 {made by Otsuka Electronics Co., Ltd.}].

  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. In the following, “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 twin-screw kneader, a polycarbonate diol having an Mn of 1,000 “Asahi Kasei PCDL-T4671” [Asahi Kasei Chemicals Co., Ltd.] 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, ion exchange water is fed from the water tank (T1) of FIG. 1 through the pump (P1) into the reactor (R1) at a flow rate of 40 ml / min. The heater (H1) and the pressure adjustment valve (V1) The reactor (R1) was controlled so that the temperature inside the reactor (R1) was 400 ° C. and the pressure was 30 MPa, and with the cooler (C1), the (V1) outlet temperature was controlled to be 30 ° C. to obtain a steady state. Meanwhile, 300.7 parts of the cut polyurethane resin (U-1), 688.4 parts of ion-exchanged water and 10.9 parts of 25% ammonia water (neutralizing agent) are placed in the raw material tank (T2) of FIG. Stir and mix. Next, the slurry in (T2) is fed from the raw material tank (T2) through the slurry pump (P2) into the reactor (R1) at a flow rate of 60 ml / min, and further the heater (H1) and pressure control valve In (V1), the internal temperature was controlled to 400 ° C. and the pressure to 30 MPa. The slurry was recovered in the recovery tank (T3) for 30 minutes from the time when the temperature and pressure were stabilized, and 1,000 parts of polyurethane resin aqueous dispersion (Q-1) was obtained. In addition, the residence time of the fluid in the reactor (R1) was 2 minutes, and the time until it was cooled by the cooler (C1) and reached the outlet temperature (30 ° C.) was 5 seconds. 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, and the prepolymer was dispersed in water at 30 ° C. 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.
<Urea group content>
The urea group content of the polyurethane resin is calculated from the N atom content determined by a nitrogen analyzer [ANTEK7000 (manufactured by Antec)] and the ratio of urethane groups and urea groups determined by ¹ H-NMR. ^{The 1} H-NMR measurement is carried out by the method described in “Structural study of polyurethane resin by NMR: Takeda Laboratory Report 34 (2), 224-323 (1975)”. That is, when ¹ H-NMR is measured and an aliphatic group is used, the urea group is determined from the ratio of the integral amount of hydrogen derived from a urea group near a chemical shift of 6 ppm and the integral amount of hydrogen derived from a urethane group near a chemical shift of 7 ppm. The weight ratio of the urethane groups is measured, and the urethane group and urea group contents are calculated from the weight ratio and the N atom content. When aromatic isocyanate is used, the weight ratio of urea groups to urethane groups is calculated from the ratio of the integral amount of hydrogen derived from urea groups near the chemical shift of 8 ppm and the integral amount of hydrogen derived from urethane groups near the chemical shift of 9 ppm.

<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.
<Concentration of solid content>
About 1 g of polyurethane resin aqueous dispersion was thinly spread on a Petri dish, weighed accurately, then weighed precisely after heating at 130 ° C for 45 minutes using a circulating constant temperature dryer, and heated to the weight before heating The percentage (percentage) of the remaining residual weight is calculated.
<Viscosity>
The viscosity of the polyurethane resin aqueous dispersion is measured using a B-type rotational viscometer at a constant temperature of 25 ° C. <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.

T1: Water tank T2: Raw material tank T3: Recovery tank P1: Pump P2: Slurry pump H1: Heater R1: Tube reactor C1: Cooler V1: Pressure adjustment valve

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 dissolved in water (A) in a supercritical state or a subcritical state, cooling and A process for producing a polyurethane resin aqueous dispersion (Q), wherein polyurethane resin particles (U1) having a volume average particle diameter (Dv) of 0.005 to 5 μm are formed by performing at least one of operations of reduced pressure.   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 (U) is a polyurethane resin obtained by subjecting a polyol and a polyisocyanate to a urethanization reaction at 100 to 250 ° C in a uniaxial or biaxial kneader. A method for producing an aqueous polyurethane resin dispersion.   4. The granulation of the polyurethane resin (U) to a particle size of 0.2 to 200 mm and the production of the polyurethane resin aqueous dispersion (Q) are carried out continuously after the urethanization reaction. The manufacturing method of the polyurethane resin aqueous dispersion of description.   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, wherein the unit 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.

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