JP4647952B2 - 2,2'-bis (hydroxymethyl) butanoic acid powder and method for producing aqueous polyurethane resin - Google Patents

Description

  The present invention relates to 2,2′-bis (hydroxymethyl) butanoic acid powder, and in particular, can be suitably used as a raw material for an aqueous polyurethane resin having excellent durability such as water resistance, heat resistance, light resistance, and alkali resistance. It relates to 2,2′-bis (hydroxymethyl) butanoic acid with controlled particle size.

  2,2'-bis (hydroxymethyl) alkanoic acid is used as a raw material for aqueous polyurethane resins, polyester resins, alkyd resins, polycarbonate resins, plasticizers, lubricants, surfactants, base materials for cosmetics, reactive monomers, etc. Widely used.

  In the production of aqueous polyurethane resins, conventionally, 2,2′-bis (hydroxymethyl) alkanoic acid represented by the following general formula (1) is used as 2,2′-bis (hydroxymethyl) propionic acid (hereinafter referred to as DMPA (dimethylolpropion). Acid) may be abbreviated. Specifically, in the presence of an organic solvent, a polyisocyanate, a polyol and DMPA are reacted to obtain a urethane prepolymer. After neutralization, water is added to perform phase inversion (water dispersion) to have two or more amino groups. After chain extension with a diamino compound, an aqueous polyurethane resin is produced by removing the solvent. DMPA has poor solubility in polyol compounds, polyisocyanate compounds and the like, and requires an organic solvent such as N-methyl-2-pyrrolidone in the production process as described above.

  However, the use of an organic solvent necessitates a desolvation step, which not only increases the cost of the product, but also deteriorates the working environment, measures against the release of volatile organic substances into the atmosphere, N-methyl-2 -Problems such as pyrrolidone toxicity occur.

  Therefore, in recent years, 2,2′-bis (hydroxymethyl) butane represented by the following general formula (2) having excellent solubility in raw material polyisocyanate and polyol as 2,2′-bis (hydroxymethyl) alkanoic acid An acid (hereinafter sometimes abbreviated as DMBA (dimethylolbutanoic acid)) is used, and a method of producing an aqueous polyurethane resin without a solvent is being adopted (see, for example, Patent Document 1).

  However, when DMBA is used in the production of an aqueous polyurethane resin, there is a problem that the fluctuation of physical properties between lots of the produced aqueous polyurethane resin is large and the durability is inferior.

Japanese Patent Application Laid-Open No. 8-259984

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a raw material DMBA for producing an aqueous polyurethane resin having uniform physical properties between lots and excellent durability. .

  In order to achieve the above object, the present inventors have intensively studied, and as a result, by using DMBA powder having a specific particle size distribution as a raw material of the aqueous polyurethane resin, an aqueous polyurethane having excellent durability can be obtained. The inventors have found that a resin can be stably produced, and have completed the present invention.

That is, the gist of the present invention is that 2,2′-bis (hydroxymethyl) butanoic acid powder having a particle size of 1.0 mm or more and less than 1.0% by weight, a polyisocyanate compound, and a polyol The present invention resides in a method for producing an aqueous polyurethane resin comprising reacting a compound as a raw material.

  The DMBA powder having a specific particle size distribution of the present invention can be suitably used as a raw material for an aqueous polyurethane resin, and the obtained aqueous polyurethane resin has excellent durability and uniform physical properties.

  Hereinafter, the present invention will be described in detail. The 2,2'-bis (hydroxymethyl) butanoic acid (DMBA) powder of the present invention is a powder having a particle content of 1.0 mm or more and less than 1.0% by weight. Preferably, in the DMBA powder of the present invention, the content of particles having a particle size of 1.0 mm or more is less than 1.0% by weight, and the content of particles having a particle size of 800 μm or less is 95% by weight or more. . As a more preferred embodiment, the DMBA powder of the present invention has a content of particles having a particle size of 1.0 mm or more of less than 1.0% by weight, and a content of particles having a particle size of 600 μm or less is 95% by weight or more. . In the case of a DMBA powder containing 1.0% by weight or more of particles having a particle size of 1.0 mm or more, if an aqueous polyurethane resin is produced using the DMBA powder, the fluctuation of physical properties between lots of the aqueous polyurethane resin is large. In addition, durability such as water resistance, heat resistance, light resistance and alkali resistance deteriorates. Moreover, it is preferable that the DMBA powder of the present invention does not contain a lump of 1.0 cm or more.

  The particles in the DMBA powder of the present invention are the smallest units that can be dispersed without destroying the essential structure, and may be not only single crystal particles but also an aggregate structure of small crystallites. The particle shape of the DMBA particles constituting the DMBA powder is not particularly limited, and examples thereof include a granular shape, a cubic shape, a plate shape, a column shape, a rod shape, and a square shape. Many particle shapes exist depending on particle generation conditions, and change depending on the metal content in the particles, the influence of inorganic substances other than DMBA, organic substances, and the like. In addition, since DMBA particles have crystal polymorphism, the shape of the particles, such as a prismatic shape or a needle shape, may change greatly. In the crystallization operation that is used when DMBA is industrially taken out as particles, it is usually a mass particle in which a large number of small crystallite aggregate structures are aggregated.

  The method for measuring the particle size of DMBA particles in the present invention is not particularly limited, and examples thereof include a method of measuring according to a sieving test method for chemical products shown in JIS-K0069. The particle size measured according to the sieving test method for chemical products shown in JIS-K0069 corresponds to the opening of the sieve. In addition, since DMBA is solidified by adhering moisture, it is preferable to measure by dry sieving. The sieving operation may be either manual sieving or mechanical sieving, and is not particularly limited. As the sieve to be used, a mesh sieve specified in JIS-Z 8801 is used. The content (% by weight) of DMBA particles can be determined based on the sieve residue defined in JIS-K0069. For example, the content of particles having a particle size of 1.0 mm or more is the percentage of the weight on the sieve after sieving with a sieve having an opening of 1.0 mm with respect to the weight of the sample.

  Further, the particle size and particle size distribution of the DMBA particles in the present invention may be measured using a particle size distribution measuring device. Examples of the particle size distribution measuring device include a LA-500 type particle size distribution measuring device manufactured by Horiba, Ltd.

  The DMBA production method is not particularly limited, and the most common method is to obtain 2,2′-bis (hydroxymethyl) butanal by performing an aldol reaction between normal butyraldehyde and formaldehyde in the presence of a basic catalyst. Next, a method of oxidizing the obtained 2,2′-bis (hydroxymethyl) butanal (Japanese Patent Laid-Open No. 11-10039) is exemplified.

  As said formaldehyde, it is preferable to use formalin diluted with water from the surface of handling, and formaldehyde concentration is 5 to 60 weight% normally, Preferably it is 30 to 55 weight%. As the basic catalyst, a water-soluble base (condensation catalyst) catalyst such as an alkali metal hydroxide or carbonate, an alkaline earth metal hydroxide or carbonate, or a tertiary amine compound is used. Two or more of these water-soluble bases may be used in combination.

  Examples of the alkali metal hydroxide include sodium hydroxide and potassium hydroxide. Examples of the carbonate include sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate and the like. Examples of the compound include aliphatic, alicyclic or heterocyclic amines having usually 3 to 20 carbon atoms, preferably 3 to 15 carbon atoms. Among them, aliphatic tertiary amines are preferable.

  Examples of the aliphatic tertiary amine include trimethylamine, triethylamine, tri-n-propylamine, tri-iso-propylamine, tri-n-butylamine, tri-iso-butylamine, and tri-tert-butylamine. Amines; asymmetric trialkylamines such as methyldiethylamine, dimethylethylamine, ethyldi-iso-propylamine, dimethyl-tert-butylamine; diamines such as N, N-tetramethyl-ethylenediamine and triethylenediamine; N, N-dimethylcyclohexylamine; Bis (2-hydroxyethyl) -cyclohexylamine, N-methylpyrrolidine, N-methylpiperidine, N-methylmorpholine, N, N-dimethylaminoethanol, N, N-dimethylaminoneope An amine having a substituent such as tanol; an amine having an aromatic ring such as tribenzylamine or N, N-dimethylbenzylamine; a tertiary amino group such as triethylenediamine or bis (2-dimethylaminoethyl) -methylamine; Examples of polyamines include: tetraalkylammonium hydroxides such as tetraethylammonium hydroxide and the like, among which trialkylamines are preferable.

  Examples of a method for oxidizing 2,2′-bis (hydroxymethyl) butanal include methods such as oxidation with hydrogen peroxide, oxidation with perisobutyric acid, oxidation with oxygen or air, and nitric acid oxidation. A method of oxidizing with hydrogen water is common. As the hydrogen peroxide solution, an aqueous solution of usually 20 to 60% by weight, preferably 40 to 60% by weight is used. In addition, when the obtained 2,2′-bis (hydroxymethyl) butanal contains a metal colloid, a metal oxide, a heavy metal salt, etc., there is a possibility of promoting the decomposition of hydrogen peroxide. It is preferable to remove. The hydrogen peroxide solution may contain a stabilizer such as phosphoric acid, uric acid, or a derivative thereof.

  As another method for producing DMBA, trimethylolpropane and formaldehyde are reacted in the presence of an acidic catalyst, the product is oxidized in the presence of an acid catalyst mainly composed of nitric acid, and the cyclic product obtained in the presence of an acidic catalyst is obtained. A method of decomposing carboxylic acid can also be used (see JP 2002-226426 A).

  DMBA obtained by each of the above production methods can be obtained as particles by cooling crystallization. The crystallization solvent is not particularly limited. For example, alcohols such as methanol, ethanol, propanol and isopropyl alcohol, aliphatic ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, ethyl acetate, propyl acetate, butyl acetate and isobutyl acetate. Aliphatic esters such as acetonitrile, aliphatic nitriles such as acetonitrile and propionitrile, etc. can be used, preferably aliphatic ketones, particularly preferably methyl isobutyl ketone.

  The amount of the crystallization solvent used is usually 1 to 10 times, preferably 1.5 to 5 times as a weight ratio to DMBA. When the amount of the crystallization solvent used is too large, the amount of DMBA dissolved increases and the crystallization rate decreases, and when it is too small, the purity of DMBA decreases. The water content in the crystallization solvent is usually 10% by weight or less, preferably 7% by weight or less.

  When the crystallization solvent contains a metal component, the metal is taken into the crystallized DMBA particles and causes deterioration of the quality of the aqueous polyurethane resin using the DMBA particles. Therefore, the crystallization solvent should not contain the metal component. Is preferred. The total content of alkali metal (or salt thereof) and alkaline earth metal (or salt thereof) in the crystallization solvent is usually 30 ppm or less, preferably 15 ppm or less. Further, the total content of metals belonging to Groups 3 to 14 of the periodic table is usually 5 ppm or less, preferably 2 ppm or less.

  The cooling rate in the cooling crystallization is usually 15 ° C./Hr or less, preferably 10-15 ° C./Hr. When the temperature before cooling crystallization is not so high, the most preferable cooling rate for obtaining the DMBA particles of the present invention is 5 ° C./Hr or less. However, since the temperature before cooling crystallization is usually high, the crystallization time becomes too long at a cooling rate of 5 ° C./Hr or less, and industrial productivity is inferior. When the cooling rate is 15 ° C./Hr or higher, the DMBA particles are difficult to handle such as fine powder or needle crystals.

  The temperature at which the cooling crystallization is completed is usually 30 to -10 ° C, preferably 10 to -5 ° C. When crystallization is completed at a temperature higher than 30 ° C., uncrystallized DMBA remains in the solvent, resulting in poor industrial productivity. When crystallization is completed at a temperature lower than −10 ° C., the purity of DMBA decreases due to precipitation of impurities.

  The DMBA slurry after cooling crystallization can be taken out as a powder by solid-liquid separation. Solid-liquid separation can be performed by, for example, a centrifuge. The residual ratio of the solvent in the DMBA particles after solid-liquid separation is usually 5% by weight or less, preferably 3% by weight or less, based on the undried particles after solid-liquid separation. When the solvent residual ratio exceeds 5% by weight, the purity of the DMBA powder is reduced, or the DMBA particles are aggregated to form particles having a large particle size. Ideally, the solvent residual ratio should be 1% by weight or less, but this is industrially disadvantageous because of the long separation time. If the solvent residual ratio is 3% by weight or less, there is no problem in the quality of DMBA particles.

  When the residual ratio of the solvent and moisture of the DMBA powder after solid-liquid separation is high, drying is preferable. Drying is performed under normal pressure or reduced pressure, and at a temperature lower than the melting point of DMBA until the desired moisture content is achieved. The melting point of DMBA is in the range of 107 to 116 ° C., and varies depending on the purity, water content and the like. The water content after the drying step is usually 0.5% by weight or less, preferably 0.2% by weight or less.

  In the DMBA powder of the present invention, the content of a polyol compound having a trifunctional or higher functional group capable of reacting with an isocyanate group such as trimethylolpropane (TMP) at a low temperature is usually 1.0% by weight or less, preferably 0.8%. 5% by weight or less, more preferably 0.1% by weight or less. A tri- or higher functional polyol compound such as TMP has the effect of increasing the branching of the urethane prepolymer when DMBA is used as a raw material for the aqueous polyurethane resin. If the content exceeds the above range, the viscosity of the urethane prepolymer This causes an increase in the particle size of the aqueous polyurethane resin. Further, when lot runout occurs in the TMP content in the DMBA powder, it causes lot runout in the viscosity of the urethane prepolymer and the particle size of the aqueous polyurethane resin.

  In the above production method, the DMBA powder having the particle size distribution of the present invention can be obtained by controlling cooling crystallization conditions, solid-liquid separation conditions, and the like. When the obtained DMBA powder is not in the particle size distribution range of the present invention, the particle size distribution range of the present invention can be achieved by the following method. For example, when the content of particles having a particle size of 1.0 mm or more is 1.0% by weight or more, according to the sieving test method for chemical products shown in JIS-K 0069, the mesh sieve specified in JIS-Z 8801 is used. By sieving using a sieve having a minimum aperture of 1 mm and removing the sieve residue, particles having a particle diameter of 1 mm or more can be made less than 1.0% by weight.

  Furthermore, when the content of particles having a particle size of 800 μm or less, which is a preferred embodiment of the present invention, achieves a particle size distribution range of 95% by weight or more, a sieve having a minimum mesh opening of 800 μm is used. In the case of achieving a particle size distribution range in which the content of particles having a particle size of 600 μm or less, which is a more preferable embodiment, is 95% by weight or more, a screen having a minimum mesh opening size of 600 μm is used. The sieving may be performed.

  If the particles are charged during sieving and adhere to the sieving body and sieving cannot be performed accurately, the sieving must be performed correctly by removing the static electricity by grounding or suctioning from the bottom of the sieving. I can do it.

  The angle of repose of the DMBA powder of the present invention is usually 20 to 80 degrees, preferably 35 to 70 degrees. The angle of repose of the powder can be measured by, for example, a three-wheeled cylinder rotation method. Specifically, a sample is put into a cylindrical container, and is rotated at an equal low speed of 2 revolutions per minute, and the maximum angle formed with respect to a horizontal plane in a static equilibrium state is measured.

  The DMBA of the present invention is preferably used as a self-emulsifier of an aqueous polyurethane resin, but in addition, polyester resins, alkyd resins, polycarbonate resins, plasticizers, lubricating oils, surfactants, base materials for cosmetics, reactive monomers, etc. It can be used as a raw material. Hereinafter, an aqueous polyurethane resin using DMBA and a method for producing the same will be described.

  The aqueous polyurethane resin includes the DMBA powder (a) of the present invention, a polyisocyanate compound (b) having two or more isocyanate groups in the molecule, a polyol compound (c) having two or more hydroxyl groups in the molecule, It is obtained using a chain extender (d) having two or more active hydrogen atoms capable of reacting with an isocyanate group in the molecule as a main raw material. The method for producing the aqueous polyurethane resin is not limited except that the DMBA powder (a) of the present invention is used, and a conventionally known method can be adopted. That is, the DMBA powder (a) of the present invention, the polyisocyanate compound (b), the polyol compound (c) having two or more hydroxyl groups in the molecule, and the short chain diol used as necessary are reacted. To produce a urethane prepolymer having an NCO group at the end.

  In the production of the urethane prepolymer, the equivalent ratio of the NCO group of the polyisocyanate compound (b) to the hydroxyl group of the polyol compound (c) is usually NCO group / OH group = 1.1 to 30/1.

  Since the aqueous polyurethane resin of the present invention uses DMBA, the polyisocyanate compound (b) and the polyol compound (c) can be reacted without using an organic solvent. However, an organic solvent may be used to facilitate subsequent emulsification / dispersion operations. The organic solvent preferably has a boiling point of 50 to 120 ° C. so that it can be easily removed after making the resin aqueous. For example, acetone (boiling point 56.3 ° C.), methyl ethyl ketone (boiling point 79.6 ° C.), methyl isobutyl ketone ( Boiling point 117 ° C), tetrahydrafuran (boiling point 66 ° C), 1,4-dioxane (boiling point 101.4 ° C), ethyl acetate (boiling point 76.8 ° C), toluene (boiling point 110.6 ° C), etc. . Among them, acetone and methyl ethyl ketone are preferable because the polyurethane resin has good solubility and can be easily removed, and acetone is particularly preferably used.

  The urethanization reaction can be carried out without a catalyst, but in order to accelerate the reaction, for example, an organometallic catalyst such as dibutyltin dilaurate, dibutyltin dioctoate, stannous octoate, a third such as triethylenediamine, toluethylamine, tributylamine, A secondary amine catalyst may be used. The urethanization reaction temperature is usually 20 to 120 ° C. The reaction time depends on the reaction temperature, solid content, etc., but is usually about 1 to 40 hours.

  After producing the urethane prepolymer, neutralize the carboxyl group in the urethane prepolymer chain by adding a basic substance, dissolve or disperse in water, and then extend the urethane prepolymer with the chain extender (d) I can do it. Further, after production of the urethane prepolymer, a basic substance may be added after chain extension with a chain extender or a polyisocyanate compound, and dissolved or dispersed in water.

  When metal is contained in the water used for dispersing the urethane prepolymer, the quality of the aqueous polyurethane resin is deteriorated. Therefore, it is preferable to use demineralized water as the water used for dispersing the urethane prepolymer. The total content of alkali metals and alkaline earth metals in the desalted water is usually 5 ppm or less, preferably 2 ppm or less. Furthermore, the total content of metal components belonging to Groups 3 to 14 of the periodic table is usually 5 ppm or less, preferably 2 ppm or less.

  Examples of the polyisocyanate compound (b) include aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 1,5-naphthalene diisocyanate, p- or m-phenylene diisocyanate. , Cycloaliphatic diisocyanates such as isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, 1,4-cyclohexylene diisocyanate, hydrogenated tolylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, m- Examples thereof include tetramethylxylylene diisocyanate. These polyisocyanate compounds may be used in combination of two or more.

  Examples of the polyol compound (c) include polyether polyols such as polytetramethylene ether glycol, polypropylene glycol and polyethylene glycol, polyethylene adipate having a bifunctional terminal hydroxyl group obtained by condensation reaction of diol and dicarboxylic acid, and polyethylene / butylene adipate. 1,6-polybutylene adipate, polypropylene adipate, polyhexamethylene adipate, polyneopentylene adipate, poly-3-methyl-1,5-pentylene adipate, terephthalic acid or isophthalic acid, adipic acid and the like in combination Condensation reaction products with hexanediol, 3-methyl-1,5-pentanediol and the like, polyester polyols such as polycaprolactone and polymethylvalerolactone, polycarbonate polyol Ol, silicone polyol, polybutadiene polyol, polyolefin polyol, and the like. The number average molecular weight of these polyol compounds (c) is usually 400 to 5000. These polyols may be used in combination of two or more.

  As required, short-chain diols such as ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, and trimethylolpropane In addition, a short-chain triol such as glycerin, and a trifunctional polyol obtained by adding propylene oxide, ethylene oxide, ε-caprolactone or the like to these may be used together with the polyol compound (c).

  Basic substances used to neutralize the carboxyl groups in the urethane prepolymer chain include tertiary amines such as trimethylamine, triethylamine, methyldiethylamine, and tripropylamine, dimethylethanolamine, methyldiethanolamine, and triethanolamine. Examples thereof include alkanolamines such as ammonia, hydroxides or carbonates of alkali metals such as ammonia, sodium and potassium. Of these, tertiary amines and alkanolamines are preferred. The usage-amount of a basic substance is 0.5-1 equivalent with respect to 1 equivalent of carboxyl groups of a urethane prepolymer normally.

  Examples of the chain extender (d) include ethylenediamine, 1,2-propanediamine, tetramethylenediamine, hexamethylenediamine, 1,4-cyclohexylenediamine, isophoronediamine, 4,4'-dicyclohexylmethanediamine, m-xylylene. Examples include diamines such as range amine and phenylenediamine; polyethylene polyamines such as diethylenetriamine, triethylenetetramine, and tetraethylenepentamine; and hydrazine, piperazine, and hydrazine and dihydrazide compounds of adipic acid or phthalic acid. Further, short chain diols, short chain triols, trifunctional polyols used together with the above-mentioned polyol compound (c) may be used, and monoethanolamine, diethanolamine, aminoethylaminoethanol, etc. may be used in combination with the above-mentioned polyamine compound. Good. These may be used alone or in combination of two or more.

  The average dispersed particle size of the aqueous polyurethane resin produced using the DMBA powder (a) of the present invention is usually 500 μm or less, preferably 300 μm or less. When the average dispersed particle size exceeds 500 μm, problems such as deterioration of dispersion stability and deterioration of resin physical properties may occur.

  The aqueous polyurethane resin of the present invention may contain a water-soluble or water-dispersible curing agent having two or more functional groups capable of reacting with a carboxyl group in one molecule. Examples of functional groups that can react with a carboxyl group include, for example, an epoxy group, a carbodiimide group, an oxazoline group, an aziridine group, and the like. The above curing agents may be used alone or in combination of two or more. When the above curing agent is used in combination, the carboxyl group reacts when the aqueous polyurethane resin is heat-treated to increase the crosslink density, so that a resin having higher durability can be obtained. Further, the disappearance of the hydrophilic carboxyl group increases the water resistance of the resin.

  Since the aqueous polyurethane resin of the present invention is produced using the DMBA powder (a) of the present invention having a controlled particle size, it is compared with the aqueous polyurethane resin using a DMBA powder having a non-controlled particle size. And the combined effect of the said hardening | curing agent becomes remarkable. That is, not only water resistance but also durability such as heat resistance, light resistance, and alkali resistance is excellent.

  The reason why the aqueous polyurethane resin of the present invention is excellent in durability is not clear, but because there are few particles having a particle size of 1.0 mm or more, the DMBA powder quickly dissolves during the prepolymer reaction, and the reaction becomes uniform. It is thought that it is easy to be done. When there are a large number of particles with a particle size of 1.0 mm or more and the DMBA powder does not dissolve quickly, the reaction of the carboxyl groups of the DMBA powder becomes non-uniform, and the cross-linked structure becomes non-uniform, resulting in durability of the resin. It is considered to have an influence.

  Compared to polyurethane resins that use organic solvents, water-based polyurethane resins are becoming more and more important because they are adapting to environmental problems. Only paints such as automotive paints, woodwork paints, can paints, etc. Rather, they are being used in a wide variety of fields, including artificial and synthetic leather raw materials, surfactant raw materials, and microencapsulated raw materials. The water-based polyurethane resin of the present invention can be suitably used for these applications because of its stable resin properties and excellent durability. In particular, a film obtained by heat-treating the aqueous polyurethane resin of the present invention at 80 ° C. for 10 hours has excellent durability such as water resistance, heat resistance, light resistance and alkali resistance, and is extremely useful.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to these Examples, unless the summary is exceeded. An evaluation method in each example and comparative example will be described.

  The physical properties of the aqueous polyurethane resin were measured as follows.

(1) Resin solid content:
The sample was weighed 1 to 1.5 g in an aluminum cup, and heated and dried at 110 ° C. for 1 hour.

(2) Viscosity:
Using an EM type rotational viscometer manufactured by Tokyo Keiki Co., Ltd., the viscosity at 25 ° C. was measured.

(3) Average particle size:
It measured using the Horiba LA-500 type | mold particle size distribution measuring apparatus.

  The durability and mechanical properties of the polyurethane film were evaluated as follows.

(4) Alkali resistance:
The polyurethane film was immersed in a 5% aqueous solution of sodium hydroxide for 24 hours, taken out, dried, and cured at room temperature for 24 hours, and then the tensile strength and elongation of the film were measured. The tensile strength and elongation retention after the durability test relative to the tensile strength and elongation before the durability test were calculated.

(5) Acid resistance:
The polyurethane film was immersed in a 5% aqueous hydrochloric acid solution for 24 hours, taken out, dried, and cured at room temperature for 24 hours, and then the tensile strength and elongation of the film were measured. The tensile strength and elongation retention after the durability test relative to the tensile strength and elongation before the durability test were calculated.

(6) Light resistance:
The polyurethane film was tested with a xenon weather meter for 150 hours, and then the tensile strength and elongation of the film were measured. The tensile strength and elongation retention after the durability test relative to the tensile strength and elongation before the durability test were calculated.

(7) Heat resistance:
After heating in an oven at 120 ° C. for 7 days and curing at room temperature for 24 hours, the tensile strength and elongation of the film were measured. The tensile strength and elongation retention after the durability test relative to the tensile strength and elongation before the durability test were calculated.

(8) Measurement of tensile strength and elongation of film:
The film after the durability test was cut into a short rail shape having a length of 10 mm and a width of 120 mm with a punching blade, and measured according to JIS K5400 using a Tensilon UTM-III-100 type tensile tester manufactured by Toyo Baldwin.

Example 1 (Production of DMBA):
DMBA was produced by the following method. In a 500 ml round bottom flask equipped with a reflux condenser, 72 g of n-butyraldehyde and 98 g of a 52 wt% formaldehyde aqueous solution were added, and 10.6 g of a 30 wt% NaOH aqueous solution was added dropwise while heating to 40 ° C. The reaction was carried out at a liquid temperature of 60 ° C. for 1 hour. Subsequently, the low boiling point component containing n-butyraldehyde was distilled off at 90 ° C. and normal pressure. 156 g of the resulting reaction station was heated to 60 ° C., and 51 g of 35% by weight hydrogen peroxide solution was added dropwise over 2 hours, followed by further reaction for 5 hours. To 200 g of the resulting oxidation reaction solution, 7.9 g of 47 wt% sulfuric acid was added to make sodium derived sodium from sodium sulfate, 90 g of water was distilled off at 60 ° C. under reduced pressure, and 208 g of methyl isobutyl ketone was added. . The amount of water in the reaction solution was 0.7% by weight. After the sodium sulfate precipitated as the water content decreased was filtered off, the filtrate was cooled to 0 ° C. at a cooling rate of 0.20 ° C./min to precipitate DMBA crystals. The obtained DMBA crystal slurry was solid-liquid separated to recover DMBA and dried at 60 ° C. for 24 hours. The obtained DMBA powder had a residual water content of 0.01% by weight, a melting point (final melting) of 115 ° C., an Na concentration of 8.2 ppm, and a total nitrogen amount of 10 ppm, and had a particle size distribution shown in Table 1.

Comparative Examples 1-2 (production of DMBA):
The DMBA powder obtained in Example 1 was subjected to dry sieving by a sieving test method according to JIS-K0069. First, sieves having openings of 600 μm, 800 μm, and 1 mm were sequentially stacked from below. Next, the DMBA powder obtained in Example 1 was put on a sieve having an opening of 1 mm at the top, and sieved by shaking the sieve. The DMBA powder remaining on each sieve was mixed at an appropriate ratio to prepare DMBA powders having a particle size distribution as shown in Table 1.

Example 2 (Production of aqueous polyurethane):
Into a four-necked flask, 133.6 g of isophorone diisocyanate, 190.4 g of polytetramethylene glycol (molecular weight of about 1000) and 18.0 g of DMBA obtained in Example 1 were added, and stirred at a liquid temperature of 90 ° C. while blowing nitrogen gas. A urethane prepolymer was produced. After stirring for 1 hour, the isocyanate group content was measured to confirm that the theoretical amount was reached, and the liquid temperature was cooled to 50 ° C. The content of the isocyanate group was determined by adding di-n-butylamine to react with the isocyanate group and then back-titrating excess di-n-butylamine with hydrochloric acid (Anal. Chem, 20 1084 ( 1948)).

  Next, 12.3 g of triethylamine was added for neutralization, and after stirring for 30 minutes, demineralized water was added dropwise over 6 minutes to perform phase inversion. Next, an aqueous solution composed of 15.4 g of hydrazine monohydrate / 64.3 g of demineralized water was added dropwise over 7 minutes to carry out a chain extension reaction, and the mixture was stirred at 40 ° C. for 3 hours to obtain an aqueous solution having a solid content of 34.9 wt% 994.0 g of polyurethane resin was obtained (referred to as Run-1). Using the same raw material as above, an aqueous polyurethane resin was further produced twice under the same conditions (referred to as Run-2 and Run-3). Table 2 shows the physical property evaluation of the obtained aqueous polyurethane resin. The physical properties of the resins obtained from Run-1 to 3 were found to be uniform and reproducible.

  Next, after adding 3 parts by weight of “Denacol CR-5L” (polyfunctional epoxy resin) manufactured by Nagase Kasei Kogyo Co., Ltd. to 100 parts by weight of each of the resins obtained in Runs 1 to 3, a doctor blade was used. And it apply | coated to the glass plate so that film thickness might be set to 200 micrometers. Subsequently, after drying at 80 degreeC for 10 hours, it was immersed in demineralized water for 30 minutes, peeled from the glass plate, and obtained the transparent polyurethane film. The results of the durability test are shown in Table 4. The three types of films prepared from the resins obtained from Run-1 to 3 showed almost the same durability, good reproducibility, and excellent alkali resistance, light resistance, and heat resistance.

Comparative Example 3 (Production of aqueous polyurethane):
Three types of water-based polyurethane resins (Run-4 to 6) were obtained in the same manner as in Example 2 except that DMBA obtained in Comparative Example 2 was used as a raw material for the urethane prepolymer. Table 2 shows the physical property evaluation of the obtained aqueous polyurethane resin. The dispersion of physical properties of the resins obtained with Runs 4 to 6 was large, and the dispersibility of Run-6 was poor.

  Next, a transparent polyurethane film was obtained by the same operation as in Example 2. The results of the durability test are shown in Table 4. As a result of the durability test, variations in durability of the three types of films prepared from the resins obtained in Runs 4 to 6 were large, and alkali resistance, light resistance, and heat resistance were also the same as those of Run-1 to Example 3 in Example 2. It was inferior in comparison.

Comparative Example 4 (Production of aqueous polyurethane):
Three types of water-based polyurethane resins (Run-7 to 9) were obtained by the same method as in Example 2 except that DMBA obtained in Comparative Example 3 was used as a raw material for the urethane prepolymer. Table 2 shows the evaluation of physical properties of the obtained aqueous polyurethane resin. The dispersion of physical properties of the resins obtained with Run-7 to 9 was large, and the dispersibility of Run-9 was poor.

  Next, a transparent polyurethane film was obtained by the same operation as in Example 2. The results of the durability test are shown in Table 4. As a result of the durability test, variations in durability of the three types of films prepared from the resins obtained in Runs 7 to 9 are large, and the alkali resistance, light resistance, and heat resistance are also the same as those of Runs 1 to 3 of Example 2. It was inferior in comparison.

Claims (3)

And the content of the particle size 1.0mm or more of the particles is less than 1.0% by weight of 2,2'-bis (hydroxymethyl) butane Sankotai, a polyisocyanate compound, reacting the polyol compound as a starting material A method for producing an aqueous polyurethane resin comprising: 2. The method for producing an aqueous polyurethane resin according to claim 1, wherein the content of 2,2′-bis (hydroxymethyl) butanoic acid powder as a raw material has a particle size of 800 μm or less is 95% by weight or more. 3. The method for producing an aqueous polyurethane resin according to claim 1, wherein the content of the 2,2′-bis (hydroxymethyl) butanoic acid powder as a raw material has a particle size of 600 μm or less is 95% by weight or more.