JP5797954B2 - Water-dispersible urethane prepolymer, water-dispersed polyurethane resin and water-based coating composition using the same - Google Patents

Description

  The present invention provides a water-dispersed polyurethane resin having excellent balance of physical properties such as oil resistance, hydrolysis resistance, weather resistance, flexibility and the like, and a coating film having good folding processability and self-healing property, and this water dispersion The present invention relates to a water-dispersible urethane prepolymer for forming a polyurethane resin and a water-based coating composition using the water-dispersed polyurethane resin.

  The water-dispersed polyurethane resin is widely used as a component of paints for flooring materials, wall materials, automobiles and the like because it provides a coating film having abrasion resistance, adhesion, and rubber elasticity. However, the physical properties of the coating film cannot be said to be sufficient as compared with solvent-based paints containing polyurethane resin as a component. In particular, in the case of a polyurethane emulsion using a polyester polyol, in addition to insufficient hydrolysis resistance of the coating film, there is also a disadvantage that the molecular weight decreases during storage of the emulsion. Moreover, when a polyether polyol is used, the heat resistance is not sufficient and the application is limited.

  In order to improve hydrolysis resistance, heat resistance, wear resistance and the like, a polyurethane emulsion using a polycarbonate diol has been proposed. For example, an organic diisocyanate, an amorphous polycarbonate diol, and a urethane prepolymer composed of a compound having one hydrophilic center and at least two isocyanate-reactive groups, and a reaction product of a chain extender, A polyurethane dispersion that provides a coating film excellent in hydrolyzability, durability, and low-temperature texture has been proposed (see Patent Document 1). In addition, a polyisocyanate component which essentially contains a diisocyanate and optionally contains other polyisocyanate compounds, a polycarbonate diol having an average molecular weight of 500 to 50,000 and a carboxyl group-containing diol, and a polyol component and monoamine compound which optionally contains other polyol compounds Water-dispersible polyurethane composition obtained from an amine component, a carboxyl group neutralizing agent component, and water optionally containing a diamine compound, and an automotive paint using the water-dispersible polyurethane composition are also proposed. (See Patent Document 2). Further, the polyurethane resin is obtained from an isocyanate group-terminated urethane prepolymer using polycarbonate diol as at least one polyol component, and based on the weight of the polyurethane resin, 2.0 to 4.0% by weight of carboxyl groups, 8 A polyurethane resin emulsion containing 0.0 to 14.0% by weight of urethane groups and 1.5 to 9.0% by weight of urea groups has been proposed (see Patent Document 3).

  When the above-mentioned various polyurethane emulsions are used, physical properties such as oil resistance, sweat resistance, hydrolysis resistance, weather resistance, flexibility and adhesion can be imparted in a more balanced manner. However, in recent years, in addition to the above-mentioned performance, there has been a demand for a self-repairing function for bending workability and scratches of the coating film. For example, there has been proposed a water-dispersed slurry paint having sufficient coating strength at the upper layer of the coating film and excellent in scratch resistance and scratch recovery properties at the lower layer of the coating film (see Patent Document 4). Further, it comprises at least a water-soluble and / or water-dispersible polymer having two or more epoxy groups in the molecule, a curing agent, an organic solvent, and water, and the curing agent contains an aliphatic tricarboxylic acid. There has been proposed an aqueous curable composition that can provide a coating film having excellent bending resistance (see Patent Document 5).

  However, a water-based coating composition containing a water-dispersed polyurethane resin, which has a good balance of physical properties such as oil resistance, hydrolysis resistance, weather resistance, and flexibility, and can provide a coating film having good folding workability and self-healing properties. Did not exist.

Japanese Patent No. 3151532 JP 2005-220255 A JP 2006-22221 A JP 2005-206668 A Japanese Patent Laid-Open No. 2005-220241

  The present invention provides a water-dispersed polyurethane resin having excellent balance of physical properties such as oil resistance, hydrolysis resistance, weather resistance, flexibility and the like, and a coating film having good folding processability and self-healing property, and this water dispersion An object is to provide a water-based paint composition using a water-dispersible urethane prepolymer and a water-dispersed polyurethane resin for forming a polyurethane resin.

  As a result of intensive studies to solve the above problems, the present inventor has obtained an aqueous dispersion obtained by reacting a polycarbonate diol having a specific structure with an organic isocyanate and an isocyanate-reactive compound having one hydrophilic center. The present inventors have found that the above-mentioned problems can be solved by using a water-soluble urethane prepolymer.

［２］上記［１］の水分散性ウレタンプレポリマーと鎖延長剤との反応生成物であり、平均粒径が１０〜１０００ｎｍである水分散ポリウレタン樹脂。
［３］上記［２］の水分散ポリウレタン樹脂を含む水系塗料組成物。 That is, the present invention has the following configuration.
[1] A water-dispersible urethane prepolymer which is a reaction product of (a) an organic isocyanate, (b) a polycarbonate diol, and (c) a compound having one hydrophilic center and at least two isocyanate-reactive groups. The polycarbonate diol (b) is a polycarbonate diol having a repeating unit represented by the following formula (A) and a terminal hydroxyl group, and 60 to 100 mol% of the repeating unit represented by the formula (A) Is a repeating unit represented by the following formula (B) or the following formula (C), and the ratio of the repeating unit represented by the formula (B) to the repeating unit represented by the formula (C) is 70:30. The water dispersible urethane prepolymer described above, characterized in that it is ˜30: 70 (molar ratio) and the primary terminal OH ratio is 95 to 99.5%.

[2] A water-dispersed polyurethane resin, which is a reaction product of the water-dispersible urethane prepolymer of [1] and a chain extender and has an average particle size of 10 to 1000 nm.
[3] A water-based coating composition containing the water-dispersed polyurethane resin of [2].

  According to the water-dispersed polyurethane resin of the present invention and the water-based coating composition using the same, it has an excellent balance of physical properties such as oil resistance, hydrolysis resistance, weather resistance, flexibility, and good folding workability and self-repairability. The coating film which has can be obtained.

Hereinafter, the present invention will be specifically described.
The water-dispersible urethane prepolymer of the present invention comprises a reaction product of an organic isocyanate (a), a polycarbonate diol (b), and a compound (c) having one hydrophilic center and at least two isocyanate-reactive groups. Consists of.

Organic isocyanate (a)
Examples of the organic isocyanate (a) used in the present invention include 2,4-triresin diisocyanate, 2,6-triresin diisocyanate and mixtures thereof, diphenylmethane-4,4′-diisocyanate (MDI), and naphthalene-1,5-diisocyanate. (NDI), 3,3′-dimethyl-4,4′-biphenylene diisocyanate (TODI), crude TDI, polymethylene polyphenylene polyisocyanate (PMDI), crude MDI, dianidine diisocyanate, tetramethylxylylene diisocyanate, and other aromatics Diisocyanate, xylylene diisocyanate (XDI), aromatic aliphatic diisocyanate such as p-phenylene diisocyanate, 4,4′-methylenebiscyclohexyl diisocyanate (hydrogenated MDI), isophorone dii Aliphatic diisocyanates such as socyanate (IPDI), cyclohexane diisocyanate (hydrogenated XDI), norbornene diisocyanate, hexamethylene diisocyanate (HDI), 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate Examples thereof include, but are not limited to, aliphatic diisocyanates such as lysidine isocyanate.

  From the viewpoint of preventing the light resistance from decreasing, it is preferable to use an alicyclic diisocyanate or an aliphatic diisocyanate, and in addition to this, from the viewpoint of hydrolysis resistance, it is more preferable to use an alicyclic diisocyanate. The organic isocyanate may be used in the form of a modified product such as carbodiimide modification, isocyanurate modification, biuret modification or the like, or may be blocked isocyanate blocked with various blocking agents. Normally, one type of organic isocyanate is selected and used, but two or more types may be selected from these organic isocyanates, and these may be mixed or sequentially added.

  Furthermore, polyisocyanate having three or more isocyanate groups in one molecule can also be used. Examples of the polyisocyanate having 3 or more isocyanate groups in one molecule include triisocyanate triisocyanate, 1-methylbenzol, in addition to the above-mentioned isocyanurate trimer, biuret trimer, trimethylolpropane adduct compound of diisocyanate. -2,4,6-triisocyanate, dimethyltriphenylmethane tetraisocyanate and the like. Further, these may be used in the form of modified products such as isocyanurate modification and biuret modification, or may be used in the form of blocked isocyanate blocked with various blocking agents.

Polycarbonate diol (b)
The polycarbonate diol (b) used in the present invention is a polycarbonate diol having a repeating unit represented by the following formula (A) and a terminal hydroxyl group, and is 60 to 100 mol% of the repeating unit represented by the formula (A). Is a repeating unit represented by the following formula (B) or (C), and the ratio of the repeating unit represented by the formula (B) to the repeating unit represented by the formula (C) is 70: 30-30. 70 (molar ratio), and the primary terminal OH ratio is 95 to 99.5%. In the polycarbonate diol (b), the ratio of the repeating unit represented by the formula (A) is preferably 95 mol% to 100 mol%, more preferably 98 mol% to 100 mol%, and still more preferably 99 mol%. It is mol% or more and 100 mol% or less.

The primary terminal OH ratio in the present invention is such that the polycarbonate diol is heated at a temperature of 160 ° C. to 200 ° C. with stirring at a pressure of 0.4 kPa or less, and the alcohols obtained as fractions are primary at both ends. It is defined as the weight percentage of the diol that is a hydroxyl group to the total of alcohols (excluding ethanol) containing the diol. The alcohol containing diol here corresponds to the segment of the terminal portion of the polycarbonate diol. Specifically, the primary terminal OH ratio in the present invention is such that the polycarbonate diol (70 g to 100 g) is heated at a temperature of 160 ° C. to 200 ° C. with stirring under a pressure of 0.4 kPa or less. A fraction corresponding to about 1 to 2% by weight, i.e. about 1 g (0.7 to 2 g) of a fraction is obtained and recovered using about 100 g (95 to 105 g) of ethanol as a solvent. The value calculated by the following formula (1) from the value of the peak area of the chromatogram obtained by subjecting the recovered solution to gas chromatography (GC) analysis.
Primary terminal OH ratio (%) = A ÷ B × 100 (1)
A: Sum of peak areas of diols whose both ends are primary OH groups B: Sum of peak areas of alcohols (excluding ethanol) containing diols

  Specific examples of “alcohols containing diol (excluding ethanol)” detected in the GC analysis performed for the measurement of the primary terminal OH ratio are 1,5-pentanediol, 1,6- Examples include hexanediol, 1,4-butanediol, 1,5-hexanediol, 1,4-cyclohexanediol, 1,4-pentanediol, 1-butanol, 1-pentanol, and 1-hexanol. When the polycarbonate diol is heated at a temperature of 160 ° C. to 200 ° C. with stirring under a pressure of 0.4 kPa or less as described above, only the terminal portion of the polycarbonate diol is decomposed and evaporated to obtain a fraction. . The ratio of diols in which both ends are primary OH groups in all alcohols in this fraction is the primary terminal OH ratio.

  The primary terminal OH ratio in the polycarbonate diol of the present invention is 95% to 99.5%. If the primary OH terminal ratio is in the above range, when the water-dispersed polyurethane resin obtained therefrom is blended to form a water-based coating composition, the coating film has good oil resistance, hydrolysis resistance, weather resistance and the like. Has a performance balance. If the primary terminal OH group ratio is 99.5% or less, it becomes easy to control the molecular weight of the polyurethane resin depending on the production conditions of the water-dispersed polyurethane resin, and a fine high molecular weight gel is formed. The dispersion stability is not lowered. Furthermore, since the viscosity of the urethane prepolymer is appropriately adjusted, the particle size of the water-dispersed polyurethane resin can be easily controlled. On the other hand, if the primary terminal OH group ratio is 95% or more, the molecular weight of the water-dispersed polyurethane resin can be increased to a predetermined value, the strength of the coating film obtained from the water-based coating composition is increased, and bending processing is performed. And self-repairability can be improved.

  Furthermore, when the primary terminal OH group ratio is 96% to 99.5%, the molecular weight of the water-dispersed polyurethane resin is increased without forming a fine high molecular weight gel, and the polyurethane resin having a desired particle size is obtained. Therefore, a coating film having better folding workability and self-repairability can be obtained. When the primary terminal OH group ratio is 97% to 99.5%, the coating has the best balance of oil resistance, hydrolysis resistance, weather resistance, etc., and has high folding workability and self-repairability. A membrane is obtained.

  In the production of the water-dispersed polyurethane resin, when aliphatic diisocyanate or alicyclic diisocyanate is used as the organic isocyanate, these diisocyanates are less reactive than aromatic diisocyanates, and therefore the reactivity of polycarbonate diol is higher. It becomes important. Furthermore, in water-dispersed polyurethane resins, hydrolysis resistance is required, so alicyclic diisocyanates are often selected. However, since they have a bulky cyclic structure, the urethane reaction has a large effect on the structure of the polycarbonate diol used. Is done. In particular, when the OH group of the polycarbonate diol is secondary or tertiary, the steric hindrance around the OH group becomes prominent, and the synergistic effect with the bulky structure of isocyanate significantly reduces the reactivity. If the primary terminal OH group of the polycarbonate diol is within the range of the present invention, the reactivity is kept good, so that there is no time for production and a water-dispersed polyurethane resin having the desired molecular weight and structure is obtained. It is done.

  The urethane prepolymer is obtained by reacting the polycarbonate diol (b), one hydrophilic center and a compound (c) having at least two isocyanate reactivity, and the organic isocyanate (a). When the hydrophilic center is uniformly present in the urethane prepolymer, the water dispersibility of the urethane prepolymer is improved, and a water-dispersed polyurethane resin having a uniform particle size can be obtained. Furthermore, the dispersion stability of the water-dispersed polyurethane resin is also improved. As a result, the foldability and self-repairability of the coating film obtained from the water-based coating composition are also improved. On the other hand, when the reactivity of one hydrophilic center and at least two isocyanate-reactive compounds with the organic isocyanate is considerably higher than the reactivity between the polycarbonate diol and the organic isocyanate, the latter reaction is preferentially performed. Occurrence is not preferable because the hydrophilic center is localized in the urethane prepolymer. If the primary terminal OH group of the polycarbonate diol is within the scope of the present invention, it is preferable because a urethane prepolymer having a structure in which hydrophilic centers are uniformly present can be obtained because there is no great difference in the reactivity of the two reactions. .

  The method for producing the polycarbonate diol of the present invention is not particularly limited. For example, it can be produced by various methods described in Schnell, Polymer Reviews, Vol. 9, p9-20 (1994).

  The polycarbonate diol of the present invention uses 1,5-pentanediol and 1,6-hexanediol as diol raw materials. In addition to these diols, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-dodecanediol, Diols having no side chain such as 1,11-undecanediol, 1,12-dodecanediol, 2-methyl-1,8-octanediol, 2-ethyl-1,6-hexanediol, 2-methyl-1, 3-propanediol, 3-methyl-1,5-pentanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-butyl-2-ethyl- Diols having side chains such as 1,3-propanediol and 2,2-dimethyl-1,3-propanediol, 1,4-cyclohexanedi Pentanol, 2- bis (4-hydroxycyclohexyl) - cyclic diols such as propane, may be used one or more kinds of diol as a raw material. The amount is not particularly limited as long as the ratio of the repeating unit shown in the present invention is satisfied.

  Furthermore, a compound having 3 or more hydroxyl groups per molecule, for example, trimethylolethane, trimethylolpropane, hexanetriol, pentaerythritol and the like can be used within a range not impairing the performance of the polycarbonate diol of the present invention. When too many compounds having three or more hydroxyl groups in one molecule are used, gelation occurs due to crosslinking during the polymerization reaction of the polycarbonate. Therefore, even when a compound having three or more hydroxyl groups in one molecule is used, the compound is preferably 0.1 to 5% by weight based on the total amount of diols as raw materials. More preferably, the content is 1 to 2% by weight.

  The polycarbonate diol of the present invention includes, as carbonates, dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, and dibutyl carbonate, diaryl carbonates such as diphenyl carbonate, ethylene carbonate, trimethylene carbonate, 1,2-propylene carbonate, 1, Examples thereof include alkylene carbonates such as 2-butylene carbonate, 1,3-butylene carbonate, and 1,2-pentylene carbonate. Among these, one or more carbonates can be used as a raw material. The use of dialkyl carbonate and / or diaryl carbonate is preferred because a polycarbonate diol having a primary terminal OH ratio within the scope of the present invention can be easily obtained depending on conditions such as the charge ratio of diol to carbonate. Moreover, it is more preferable to use dimethyl carbonate, diethyl carbonate, diphenyl carbonate, and dibutyl carbonate from the viewpoint of availability and easy setting of conditions for the polymerization reaction.

  In the production of the polycarbonate diol of the present invention, a catalyst may or may not be added. When adding a catalyst, it can select freely from a normal transesterification catalyst. For example, lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, zinc, aluminum, titanium, cobalt, germanium, tin, lead, antimony, arsenic, cerium and other metals, salts, alkoxides, organic compounds Used. Particularly preferred are titanium, tin and lead compounds. Moreover, the usage-amount of a catalyst is 0.00001 to 0.1% of the polycarbonate diol weight normally obtained.

  An example of a method for producing polycarbonate diol will be described. The polymerization can be carried out in two stages. For example, when dimethyl carbonate is used as the carbonate, diol and dimethyl carbonate are mixed in a molar ratio of 20: 1 to 1:10 and reacted at 100 to 300 ° C. under normal pressure or reduced pressure, and the resulting methanol is dimethyl carbonate. A low molecular weight polycarbonate diol can be obtained by removal as a mixture with carbonate. Next, heating at 160 to 250 ° C. under reduced pressure removes unreacted diol and dimethyl carbonate, and self-condenses the low molecular weight polycarbonate diol to obtain a polycarbonate diol having a predetermined molecular weight. When ethylene carbonate is used as the carbonate, diol and ethylene carbonate are mixed at a molar ratio of 20: 1 to 1:10 and reacted at 100 to 200 ° C. under reduced pressure. To obtain a low molecular weight polycarbonate diol. Next, heating is performed at 130 to 250 ° C. under reduced pressure to remove unreacted diol and ethylene glycol, and self-condensation of low molecular weight polycarbonate diol can yield polycarbonate diol having a predetermined molecular weight.

  The polycarbonate diol having a primary terminal OH ratio of the present invention is the polymerization conditions such as the purity of the raw material diol, temperature and time, and when a dialkyl carbonate or / and diaryl carbonate is used as the carbonate, the charging ratio of the diol and the carbonate, etc. From the above conditions, one method can be selected or appropriately combined. Industrially obtained 1,5-pentanediol contains 0.2 to 2% by weight of 1,5-hexanediol and 1,4-cyclohexanediol as impurities having secondary hydroxyl groups, respectively. On the other hand, 1,6-hexanediol obtained industrially contains 0.1 to 2% by weight of impurities having a secondary hydroxyl group such as 1,4-cyclohexanediol. Since these diols having secondary hydroxyl groups have low transesterification reactivity during the production of polycarbonate diols, they often become terminal groups of polycarbonate diols, resulting in polycarbonate diols having secondary hydroxyl groups at the ends.

  In addition, when dialkyl carbonate and / or diaryl carbonate is used as the carbonate, polycarbonate diol is prepared by reacting the diol and carbonate in a stoichiometric amount or a proportion close thereto in accordance with the molecular weight of the target polycarbonate diol. In many cases, an alkyl group or an aryl group derived from carbonate remains at the terminal of the. Therefore, by setting the amount of diol with respect to the carbonate to 1.01 to 1.30 times the stoichiometric amount, the terminal of the alkyl group or aryl group remaining at the terminal of the polycarbonate diol can be reduced to form a hydroxyl group. . Furthermore, due to side reactions, the end of the polycarbonate diol may become a vinyl group, or when dimethyl carbonate is used as a carbonate, for example, it may become a methyl ester or a methyl ether. In general, the side reaction is more likely to occur as the reaction temperature is higher and the reaction time is longer.

  In the polycarbonate diol (b) used in the present invention, the ratio of the repeating unit represented by the above formula (B) or (C) in the repeating unit represented by the above formula (A) (hereinafter referred to as “main component ratio”) Is 60 to 100 mol%. If the main component ratio is within this range, the coating film obtained from the water-based coating composition has a good balance of performance such as hydrolysis resistance, heat resistance and flexibility. When the main component ratio is 60 mol% or more, the viscosity of the polycarbonate diol is increased, the particle size of the water-dispersed polyurethane resin is not increased, and the coating film obtained from the aqueous coating composition is also less flexible. There is nothing. When the ratio of the main component is 75 to 100 mol%, the above problem is less likely to occur. It is most preferable when the main component ratio is 90 to 100 mol%.

  In the polycarbonate diol (b) used in the present invention, the ratio of the repeating unit represented by the above formula (B) and the repeating unit represented by the above formula (C) (hereinafter referred to as “copolymerization ratio”) (B): represented by the above formula (C)) is in a molar ratio of 70:30 to 30:70. When the copolymerization ratio is within this range, the crystallinity of the polycarbonate diol is lowered, the flexibility of the coating film is increased, and bending workability and self-repairability are obtained. When the copolymerization ratio is 65:35 to 35:65 in terms of molar ratio, the crystallinity of the polycarbonate diol is further reduced. Furthermore, when the copolymerization ratio is 60:40 to 40:60, the crystallinity of the polycarbonate diol is further reduced, so that a coating film having high flexibility and good folding workability and self-repairability can be obtained. .

  Conventionally, polycarbonate diol is composed of a repeating unit represented by the above formula (C) and a terminal hydroxyl group, and has high crystallinity, but although the resulting coating film has high hydrolysis resistance, heat resistance and chemical resistance, Insufficient flexibility and limited use for coating compositions. In the present invention, the crystallinity is improved with the repeating unit (repeating unit of the above formula (B)) having a methylene chain length close to that of the repeating unit of the above formula (C), having no branched structure, and having an odd number of methylene chains. By reducing, maintaining high hydrolysis resistance, heat resistance and chemical resistance of the coating film obtained, and maintaining good flexibility, it can be used for coating composition applications. It was. Furthermore, when satisfy | filling the specific main component ratio and the copolymerization ratio, it discovered that the coating film obtained from a coating composition has bending workability and self-repairability.

The range of the average molecular weight of the polycarbonate diol (b) used in the present invention is 800 to 5000 in terms of number average molecular weight. When the number average molecular weight of the polycarbonate diol is 800 or more, folding workability and self-repairability can be obtained without lowering the strength of the coating film obtained using the water-dispersed polyurethane resin. Further, when the number average molecular weight is 5000 or less, the viscosity of the polycarbonate diol does not increase, and there is no situation in which the production of the water-dispersed polyurethane resin is difficult. The number average molecular weight of the polycarbonate diol is more preferably 1000 to 3000.

The polycarbonate diol (b) of the present invention may contain a structure represented by a repeating unit of the following formula (D) in the molecule for the purpose of improving flexibility.

  The content of the repeating unit of the formula (D) in the polycarbonate diol (b) molecule is not particularly limited as long as it does not affect the present invention, but as the amount increases, heat resistance and chemical resistance are increased. descend. Accordingly, when the repeating unit represented by the formula (D) is introduced, the repeating unit of the carbonate represented by the formula (A) is represented by the formula (D) (having an ether-derived structure). The repeating unit is preferably 0.05 to 5 mol%, more preferably 0.05 to 3 mol%.

Compound (c) having one hydrophilic center and at least two isocyanate-reactive groups
The compound (c) having one hydrophilic center and at least two isocyanate-reactive groups used in the present invention is used for the purpose of maintaining the emulsion stability of the water-dispersed polyurethane resin. The hydrophilic center is, for example, a carboxylic acid group or a sulfonic acid group, and indicates a hydrophilic group that can be neutralized with an alkaline group. The isocyanate-reactive group generally refers to a group that reacts with an isocyanate such as alcohol or amine to form a urethane bond or a urea bond. Specific examples of the compound (c) include compounds represented by the following formula (E) such as 2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid and 2,2-dimethylolvaleric acid. Furthermore, diaminocarboxylic acids such as lysine, cystine, and 3,5-aminocarboxylic acid can be used, but are not limited thereto.

  When the compound (c) having one hydrophilic center and at least two isocyanate-reactive groups is used, it is usually neutralized with a neutralizing agent from the viewpoint of emulsion stability. Examples of neutralizing agents include trialkylamines such as trimethylamine, triethylamine, tri-n-propylamine, tributylamine, N, N-dimethylethanolamine, N, N-dimethylpropanolamine, N, N-dipropylethanol. Amines, N, N-dialkylalkanolamines such as 1-dimethylamino-2-methyl-propanol, N-alkyl-N, N-dialkanolamines, trialkanolamines such as triethanolamine, sodium hydroxide, potassium hydroxide Lithium hydroxide, ammonia, trimethylammonium hydroxide, and the like. The amount of the neutralizing agent is preferably 0.5 to 2.0 equivalents, more preferably 0.7 to 1.2 equivalents, relative to the number of moles of the hydrophilic center.

Chain extender The chain extender used in the present invention includes water, ethylene glycol, short chain diols such as 1,4-butanediol, hydrazine, ethylenediamine, diethyltriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, Propylenediamine, hexamethylenediamine, cyclohexylenediamine, piperazine, 2-methylpiperazine, phenylenediamine, tolylenediamine, xylenediamine, α, α'-methylenebis (2-chloroaniline), 3,3'-dichloro-α, and polyamines such as α′-biphenylamine, m-xylenediamine, isophoronediamine, N-methyl-3,3′-diaminopropylamine, and adducts of diethylenetriamine and acrylate or hydrolysis products thereof. , But it is not limited to.

  The amount of chain extender is usually 0 per mole of isocyanate groups in a urethane prepolymer comprising an organic isocyanate, a polycarbonate diol, and a compound having one hydrophilic center and at least two isocyanate-reactive groups. 0.1 to 0.95 mol, preferably 0.1 to 0.6 mol.

Production Method of Urethane Prepolymer The method for producing the urethane prepolymer of the present invention can be a known method, and is not particularly limited. For example, in the presence of an organic solvent, polycarbonate diol (b), one hydrophilic center and at least two isocyanate-reactive compound (c), and organic isocyanate (a) are reacted at a temperature of 20 to 120 ° C. Thus, a urethane prepolymer whose terminal is an isocyanate can be produced.

  In the present invention, the compounding amount of the organic isocyanate (a) is the isocyanate-reactive property of the compound (c) having a hydroxyl group of the polycarbonate diol (b), one hydrophilic center and at least two isocyanate-reactive groups. It is usually 95 to 250% equivalent, preferably 120 to 200% equivalent, based on the total with the group. If the compounding quantity of organic isocyanate (a) is said range, the structure and molecular weight of water-dispersed polyurethane resin can be designed freely. The amount of the compound (c) having one hydrophilic center and at least two isocyanate-reactive groups is not particularly limited, but is usually 0.1 to 0.1% relative to the polycarbonate diol (b). 30% by weight is used.

  In the process of producing the urethane prepolymer of the present invention, an organic solvent may be used as necessary. The organic solvent may be any solvent inert to the isocyanate. Examples include ketones such as methyl ethyl ketone and acetone, esters such as methyl acetate and ethyl acetate, acetonitrile, tetrahydrofuran, toluene, dioxane, and N-methylpyrrolidone. These can be used alone or in admixture of two or more.

  If the boiling point of the organic solvent is less than 100 ° C., that is, lower than the boiling point of water, the properties of the coating film change over time by removing only the organic solvent from the water-dispersed polyurethane resin or coating film almost completely. The occurrence of inconvenience can be prevented. Therefore, it is preferable to use an organic solvent having a boiling point of 100 ° C. or lower. When using an organic solvent, 3 to 3 weights of organic isocyanate (a), polycarbonate diol (b), and compound (c) having one hydrophilic center and at least two isocyanate-reactive groups. It can be used in an amount of 100% by weight.

  In the process of producing the urethane prepolymer of the present invention, a known catalyst may be used as necessary. Examples of the catalyst include amines such as triethylamine, N-ethylmorpholine, and triethylenediamine, tin compounds such as dibutyltin dilaurate, dioctyltin dilaurate, and tin octylate, and titanium compounds such as tetrabutyltitanate. The amount used is preferably 0.00001 to 0.1% by weight based on the urethane prepolymer produced.

Method for producing water-dispersed polyurethane resin The method for producing the water-dispersed polyurethane resin of the present invention is not particularly limited, and examples thereof include the following methods. Urethane prepolymer in which polycarbonate diol (b), at least two isocyanate-reactive compound (c) and organic isocyanate (a) are reacted with isocyanate in the presence of an organic solvent. The urethane prepolymer is poured into an aqueous solution containing a chain extender and emulsified, and after chain extension reaction, the organic solvent contained in the system is removed by a method such as distillation to obtain a water-dispersed polyurethane resin. be able to. The neutralizing agent may be used in the process of producing the urethane prepolymer, may be added before the urethane prepolymer is produced, and before being added to the chain extender-containing aqueous solution, or may be added to the chain extender-containing aqueous solution. . The chain extension reaction is usually performed at 20 to 100 ° C.

  In the process of producing the water-dispersed polyurethane resin of the present invention, an organic solvent may be used as necessary. When an organic solvent is used in the production of the urethane prepolymer to be used, an organic solvent may be further added. Similar to the production of the urethane prepolymer, the organic solvent may be any solvent inert to the isocyanate, such as ketones such as methyl ethyl ketone and acetone, esters such as methyl acetate and ethyl acetate, acetonitrile, tetrahydrofuran and toluene. , Dioxane, N-methylpyrrolidone and the like can be used alone or in admixture of two or more.

  If the boiling point of the organic solvent is less than 100 ° C., that is, lower than the boiling point of water, the properties of the coating film change over time by removing only the organic solvent from the water-dispersed polyurethane resin or coating film almost completely. The occurrence of inconvenience can be prevented. Therefore, it is preferable to use an organic solvent having a boiling point of 100 ° C. or lower. When using an organic solvent, the weight of the organic isocyanate (a), the polycarbonate diol (b), the compound (c) having one hydrophilic center and at least two isocyanate-reactive groups and the chain extender On the other hand, it can be used in an amount of 3 to 100% by weight.

  In the process of producing the water-dispersed polyurethane resin of the present invention, a known catalyst may be used as necessary. Examples of the catalyst include amines such as triethylamine, N-ethylmorpholine, and triethylenediamine, tin compounds such as dibutyltin dilaurate, dioctyltin dilaurate, and tin octylate, and titanium compounds such as tetrabutyltitanate.

  To ensure emulsion stability, anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, polymeric surfactants, reactive surfactants, etc., commonly used in emulsions Can be used.

  Nonionic surfactants include, for example, aliphatic alcohol alkylene oxide adducts, alkylphenol alkylene oxide adducts, polyhydric alcohol fatty acid esters such as sorbitan monolaurate, fatty acid alkanolamides such as coconut oil fatty acid diethanolamide, (poly Examples thereof include, but are not limited to, dialkylamine oxides such as oxyalkylene alkylphenyl ether, (poly) oxyalkylene alkylamine, and lauryldimethylamine oxide.

  Anionic surfactants include ether carboxylic acids such as sodium lauryl ether acetate or salts thereof, sulfate esters such as sodium lauryl sulfate or salts thereof, (poly) oxyethylene sodium lauryl sulfate, (poly) oxyethylene lauric acid triethanol Examples include, but are not limited to, amines, sulfonates such as sodium dodecylbenzenesulfonate, phosphate esters or salts thereof such as sodium lauryl phosphate, and fatty acid salts such as sodium laurate. Cationic surfactants include, but are not limited to, primary to tertiary amine salts, pyridinium salts, alkylpyridinium salts, and the like.

  The surfactants can be used in any amount as required, but are organic isocyanate (a), polycarbonate diol (b), and one hydrophilic center and at least two isocyanate-reactive. The amount is usually 0.1 to 30% by weight, preferably 3 to 20% by weight, based on the total weight of the urethane prepolymer which is a reaction product of the group-containing compound (c) and the chain extender.

  The state of the water-dispersed polyurethane resin of the present invention is usually an emulsion, suspension, colloidal dispersion or the like. The average particle diameter of the water-dispersed polyurethane resin in the water dispersion is preferably 10 to 1000 nm. When the average particle size of the water-dispersed polyurethane resin is 10 nm or more, the production of the water-dispersed polyurethane resin is facilitated. Can be obtained. The average particle size of the water-dispersed polyurethane resin is more preferably 10 to 500 nm, and further preferably 10 to 250 nm. When the average particle size is in such a range, the strength and chemical resistance of the coating film are improved, and the bending workability and self-repairability are further improved.

  In the water-dispersed polyurethane resin of the present invention, the amount of the solid content is not particularly limited, but is usually 10 to 70% by weight, preferably 20 to 60% by weight.

Preparation of water-based coating composition The water-based coating composition of the present invention contains the above-mentioned water-dispersed polyurethane resin as an essential component, and is prepared using other water-dispersible resins, crosslinking agents, and additives as necessary.

  Examples of the water-dispersible resin or aqueous resin composition include water-dispersed or water-soluble polyurethane resins other than the water-dispersed polyurethane resin of the present invention, acrylics, styrene / acrylic copolymers, Saran-based, vinyl acetate-based, vinyl acetate / acrylic. Synthetic resin emulsions such as copolymers and ethylene / vinyl acetate copolymers. The content of these resins in the aqueous coating composition is usually 60% by weight or less, preferably 50% by weight or less of the aqueous coating composition.

  Examples of the crosslinking agent include water-soluble or water-dispersible amino resins, water-soluble or water-dispersible polyepoxides, water-soluble or water-dispersible blocked isocyanate compounds, and polyethylene urea. The addition amount of the crosslinking agent is usually 30% by weight or less, preferably 20% by weight or less of the water-based coating composition.

  Additives generally include pigments, dyes, pigment dispersants, light stabilizers, auxiliary binders, thickeners, leveling agents, thixotropic agents, antifoaming agents, foaming agents, ultraviolet absorbers, antioxidants, reducing agents. Sticking agent, film forming aid, curing agent, silane coupling agent, antiblocking agent, antigelling agent, dispersion stabilizer, radical scavenger, inorganic or organic filler, plasticizer, lubricant, antistatic agent, antibacterial Examples include, but are not limited to, agents, fungicides, preservatives, and antifreeze agents.

  A solvent can be added for the purpose of improving the appearance of the coating film after drying. Examples of the solvent include C1-C20 monohydric alcohols such as methanol, ethanol, and propanol, glycols such as ethylene glycol, propylene glycol, and diethylene glycol, trihydric alcohols such as glycerin, and cellosolves such as methyl cellosolve and ethyl cellosolve. Can be used. The addition amount is preferably 20% by weight or less, more preferably 15% by weight or less, based on the weight of the water-based coating composition.

  The water-based coating composition of the present invention is produced by mixing and stirring the above water-dispersed polyurethane resin and each of the above optional components. In mixing, all the components may be mixed at the same time, or each component may be added in stages and mixed. The solid content concentration of the water-based coating composition of the present invention is usually 10 to 70% by weight, preferably 15 to 60% by weight.

  The water-based coating composition of the present invention can be used, for example, for plastics, metals, glass, foams, and molded products thereof. Specific examples of coating objects (base materials) include automotive interior parts such as instrument panels, center consoles and door trims, weak electrical products such as computers, televisions and washing machines, wall interior materials such as wall materials, floor materials and ceiling materials. Etc. A coating film can be formed by coating a substrate with the water-based coating composition of the present invention and drying it. In addition, a primer can be applied to the substrate before using the paint of the present invention.

  The method for applying the aqueous coating composition of the present invention to a substrate is not particularly limited. For example, spray coating, roll coater method, bell coating, disc coating, brush coating and the like can be mentioned. The coating amount can be freely set depending on the purpose of coating and the type of the substrate, but is usually applied so that the coating thickness at the time of drying is 15 to 50 μm. Drying may be performed at room temperature or may be heated. When heating, it is normally performed at 60 to 150 ° C. for 3 to 60 minutes.

EXAMPLES Next, although an Example and a comparative example demonstrate this invention in detail, this invention is not limited by these examples at all.
The physical property values shown in the following examples and comparative examples were measured by the following methods.

1) Primary terminal OH ratio of polycarbonate diol The primary terminal OH ratio of polycarbonate diol was measured by the following method. Weigh about 70 to 100 g of polycarbonate diol in a 300 cc eggplant flask and heat at about 180 ° C. with stirring under a pressure of 0.1 kPa or less using a rotary evaporator connected to a trap bulb for collecting fractions. The polycarbonate diol was heated in a bath to obtain a fraction equivalent to 1 to 2% by weight of the polycarbonate diol in the trap sphere, that is, about 1 g (0.7 to 2 g). This was recovered using about 100 g (95 to 105 g) of ethanol as a solvent, and the peak value of the chromatogram obtained by subjecting the recovered solution to GC analysis was calculated by the following formula (1).
Primary terminal OH ratio (%) = A ÷ B × 100 (1)
A: Sum of peak areas of diols having both ends at the primary OH group B: Sum of peak areas of alcohols (excluding ethanol) containing diol Gas chromatographic analysis conditions: Column: DB-WAX (US & J Company) Manufactured), 30 m, film thickness 0.25 μm, temperature rising condition: 60 ° C. to 250 ° C., detector: FID (flame ionization detector)

2) Number average molecular weight of polycarbonate diol The hydroxyl value was determined according to JIS K1557-1 and calculated using the following mathematical formula (2).
Number average molecular weight = 2 / (OH value × 10 ⁻³ /56.1) (2)

3) Copolymerization ratio and main component ratio of polycarbonate diol 1 g of a sample was taken into a 100 ml eggplant flask, 30 g of ethanol and 4 g of potassium hydroxide were added, and reacted at 100 ° C. for 1 hour. After cooling the reaction solution to room temperature, 2-3 drops of phenolphthalein was added to the indicator and neutralized with hydrochloric acid. After cooling in the refrigerator for 1 hour, the precipitated salt was removed by filtration and analyzed using GC (gas chromatography). GC analysis was performed using gas chromatography GC-14B (manufactured by Shimadzu Corporation, Japan) with DB-WAX (manufactured by J & W, USA) as a column, diethylene glycol diethyl ester as an internal standard, and a detector as FID. The temperature rising profile of the column was maintained at 60 ° C. for 5 minutes and then heated to 250 ° C. at 10 ° C./min.

(I) Copolymerization ratio Using the above analysis results, from the molar ratio of 1,5-pentanediol and 1,6-hexanediol, the copolymerization ratio (of 1,5-pentanediol when the whole is 100) The number of moles: the number of moles of 1,6-hexanediol).
(Ii) Main component ratio It calculated | required by following Numerical formula (3) using said analysis result.
Main component ratio (mol%) = {(B + C) / A} × 100 (3)
A: Total number of moles of diol derived from the repeating unit of the above formula (A)
B: Number of moles of 1,5-pentanediol
C: Number of moles of 1,6-hexanediol

4) Purity analysis of polycarbonate diol raw material diol 1,5-hexanediol and 1,6-hexanediol used as diol raw materials were analyzed by gas chromatography. The conditions were gas chromatography GC-14B (manufactured by Shimadzu Corporation) with DB-WAX (manufactured by J & W) as a column, diethylene glycol diethyl ester as an internal standard, and a detector as FID. The temperature rising profile of the column was maintained at 60 ° C. for 5 minutes and then heated to 250 ° C. at 10 ° C./min.

5) Average particle diameter of water-dispersed polyurethane resin The average particle diameter of the water-dispersed polyurethane resin was measured using a particle size analyzer Nanotrac 150 (manufactured by Microtrac).

6) Mechanical strength and elongation at break The water-dispersed polyurethane resin was stored at 40 ° C. for 1 month, then formed on a glass plate, left at room temperature for 24 hours, and then heat treated at 120 ° C. for 30 minutes to a thickness of 100 μm. A sample of a polyurethane resin film having a width of 10 mm and a length of 60 mm was obtained.
Using a Tensilon tensile tester RTC-1250A (manufactured by ORIENTEC) in a thermostatic chamber, the mechanical strength (MPa) of the sample film and the elongation (%) at break were measured with a chuck distance of 50 mm and a tensile speed of 100 mm / min. It was measured. This sample film was also used for evaluating flexibility and oil resistance.

7) Flexibility The test was performed by the method shown in 6) above, and the stress (MPa) at the time of 50% elongation (at the time of 25 mm elongation) was measured. The lower the stress, the higher the flexibility.

8) Oil resistance The oil resistance (swell ratio) after the sample film was immersed in oleic acid at 45 ° C for 1 week was measured. The oil resistance (swelling rate) was determined using the following mathematical formula (4).
Oil resistance (%) = {(weight after test−weight before test) / weight before test} × 100 (4)

9) Weather resistance After a predetermined time (200 hours) has elapsed in 60 minutes (of which precipitation is 12 minutes) in a sunshine type weatherometer WEL-SUN-DC (made by Suga Test Instruments), the above 5) Mechanical strength (MPa) was measured by the indicated method. When the value after the test was 80% or more compared to the value before the test, the weather resistance was evaluated by ◯, when the value was 60% or more and less than 80%, and when it was less than 60%. .

10) Flexibility According to JIS K5600-5-1, the flexibility of the coating film formed from the polyurethane resin was measured (curvature radius 5 mm).
As a result of visual inspection, the flexibility was evaluated with ◯ when there was no abnormality, Δ when a slight crack was generated, and x when a crack was generated as a whole.

11) Restorability A brass brush (3 rows, wire diameter 0.14 mm, hair length 16 mm) was applied to the surface of the coating film at a right angle, and a load of 300 g was applied from the top to move the brush at a speed of 1 cm / second. The brass brush was removed and the coating film after 5 minutes was visually observed. The repairability was evaluated by ◯ when there was no abnormality, Δ when the scratch was slightly left, and x when the scratch was clearly confirmed.

[Polycarbonate diol polymerization example 1]
1,5-pentanediol and 1,6-hexanediol used as raw materials were analyzed. The 1,5-pentanediol had a purity of 98.3% by weight and contained 1.2% by weight of 1,5-hexanediol and 0.1% by weight of 1,4-cyclohexanediol. The remaining 0.4% by weight of impurities was a plurality of unknowns. The 1,6-hexanediol had a purity of 98.8% by weight and contained 0.6% by weight of 1,4-cyclohexanediol. The remaining 0.6% by weight of impurities was a plurality of unknowns. In the following polymerization examples, the raw materials were used except for Polymerization Examples 8 and 12.

  In a 2 L glass flask equipped with a rectifying column packed with a regular packing and a stirrer, 430 g (4.8 mol) of dimethyl carbonate, 260 g (2.5 mol) of 1,5-pentanediol, 1,6- 310 g (2.6 mol) of hexanediol was charged. Titanium tetrabutoxide (0.09 g) was added as a catalyst, heated and stirred at a temperature of 140 to 150 ° C. under normal pressure, and reacted for 10 hours while distilling off the resulting mixture of methanol and dimethyl carbonate. Thereafter, the reaction temperature was 150 ° C. to 190 ° C. and the pressure was 10 to 15 kPa, and the reaction was carried out for 5 hours while distilling off the resulting mixture of methanol and dimethyl carbonate. Then, it was made to react at 190 degreeC for 8 hours, reducing pressure gradually to 0.5kPa. The results of analyzing the obtained polycarbonate diol are shown in Table 1. This polycarbonate diol is referred to as PC1.

[Polycarbonate diol polymerization example 2]
Using the same apparatus as in Polymerization Example 1, 420 g (4.7 mol) of dimethyl carbonate, 260 g (2.5 mol) of 1,5-pentanediol, and 270 g (2.3 mol) of 1,6-hexanediol were charged. Titanium tetrabutoxide 0.08 g was added as a catalyst, and the reaction was performed under the same conditions as in Polymerization Example 1. The results of analyzing the obtained polycarbonate diol are shown in Table 1. This polycarbonate diol is referred to as PC2.

[Polycarbonate diol polymerization example 3]
Using the same apparatus as in the above Polymerization Example 1, 500 g (4.2 mol) of diethyl carbonate, 150 g (1.4 mol) of 1,5-pentanediol, and 350 g (3.0 mol) of 1,6-hexanediol were charged. 0.10 g of titanium tetrabutoxide was added as a catalyst, heated and stirred at a temperature of 140 to 150 ° C. under normal pressure, and reacted for 10 hours while distilling off the resulting mixture of ethanol and diethyl carbonate. Thereafter, the reaction temperature was 150 ° C. to 190 ° C. and the pressure was 10 to 15 kPa, and the reaction was performed for 5 hours while distilling off the mixture of ethanol and diethyl carbonate to be produced. Then, it was made to react at 190 degreeC for 8 hours, reducing pressure gradually to 0.5kPa. The results of analyzing the obtained polycarbonate diol are shown in Table 1. This polycarbonate diol is referred to as PC3.

[Polymerized diol polymerization example 4]
Using the same apparatus as in Polymerization Example 1, 465 g (5.3 mol) of ethylene carbonate, 260 g (2.5 mol) of 1,5-pentanediol, and 330 g (2.8 mol) of 1,6-hexanediol were charged. 0.10 g of titanium tetrabutoxide was added as a catalyst, and the mixture was stirred and heated at normal pressure. The reaction temperature was 150 ° C. to 190 ° C., the pressure was 3.0 to 5.0 kPa, and the reaction was performed for 15 hours while distilling off the mixture of ethylene glycol and ethylene carbonate to be produced. Thereafter, the pressure was reduced to 0.5 kPa, and the reaction was further continued at 190 ° C. for 8 hours while distilling off ethylene carbonate and diol. The results of analyzing the obtained polycarbonate diol are shown in Table 1. This polycarbonate diol is referred to as PC4.

[Polymerized diol polymerization example 5]
Using the same apparatus as in Polymerization Example 1, the raw materials were charged under the same conditions. The mixture was heated and stirred at a temperature of 140 to 150 ° C. under normal pressure, and the mixture was reacted for 7 hours while distilling off the resulting mixture of methanol and dimethyl carbonate. Thereafter, the reaction was carried out at a reaction temperature of 150 ° C. to 190 ° C. and a pressure of 10 to 15 kPa for 3 hours while distilling off the resulting mixture of methanol and dimethyl carbonate. Then, it was made to react at 190 degreeC for 3 hours, reducing pressure gradually to 0.5kPa. The results of analyzing the obtained polycarbonate diol are shown in Table 1. This polycarbonate diol is referred to as PC5.

[Polymerized diol polymerization example 6]
Using the same apparatus as in Polymerization Example 1, 450 g (5.1 mol) of ethylene carbonate, 260 g (2.5 mol) of 1,5-pentanediol, and 310 g (2.6 mol) of 1,6-hexanediol were charged. 0.10 g of titanium tetrabutoxide was added as a catalyst, and the mixture was stirred and heated at normal pressure. The reaction temperature was 150 ° C. to 190 ° C., the pressure was 3.0 to 5.0 kPa, and the reaction was carried out for 10 hours while distilling off the mixture of ethylene glycol and ethylene carbonate to be produced. Thereafter, the pressure was reduced to 0.5 kPa, and the mixture was further reacted at 190 ° C. for 5 hours while distilling off ethylene carbonate and diol. The results of analyzing the obtained polycarbonate diol are shown in Table 1. This polycarbonate diol is referred to as PC6.

[Polymerized diol polymerization example 7]
The raw materials were charged under the conditions of Polymerization Example 6. 0.10 g of titanium tetrabutoxide was added as a catalyst, and the mixture was stirred and heated at normal pressure. The reaction temperature was 150 ° C. to 190 ° C., the pressure was 3.0 to 5.0 kPa, and the reaction was performed for 15 hours while distilling off the mixture of ethylene glycol and ethylene carbonate to be produced. Thereafter, the pressure was reduced to 0.5 kPa, and the mixture was further reacted at 190 ° C. for 15 hours while distilling off ethylene carbonate and diol. The results of analyzing the obtained polycarbonate diol are shown in Table 1. This polycarbonate diol is referred to as PC7.

[Polymerized diol polymerization example 8]
Raw materials 1,5-pentanediol and 1,6-hexanediol were purified by distillation. As a result, 1,5-pentanediol had a purity of 98.9% by weight, 1,5-hexanediol was 0.5% by weight, and 1,4-cyclohexanediol was not detected. The remaining 0.6% by weight of impurities was a plurality of unknowns. The 1,6-hexanediol had a purity of 99.1% by weight and contained 0.3% by weight of 1,4-cyclohexanediol. The remaining 0.6% by weight of impurities was a plurality of unknowns. Polycarbonate diol was polymerized using the above raw materials.

  Using the same apparatus as in Polymerization Example 1, 570 g (4.8 mol) of diethyl carbonate, 260 g (2.5 mol) of 1,5-pentanediol, and 315 g (2.7 mol) of 1,6-hexanediol were charged. Titanium tetrabutoxide 0.09 g was added as a catalyst, and the reaction was carried out under the conditions shown in Polymerization Example 3 above. The results of analyzing the obtained polycarbonate diol are shown in Table 1. This polycarbonate diol is referred to as PC8.

[Polymerized diol polymerization example 9]
Using the same apparatus as in Polymerization Example 1, 460 g (3.9 mol) of diethyl carbonate, 100 g (1.0 mol) of 1,5-pentanediol, and 370 g (3.1 mol) of 1,6-hexanediol were charged. Titanium tetrabutoxide (0.10 g) was added as a catalyst, and the reaction was carried out under the same conditions as in Polymerization Example 3. The results of analyzing the obtained polycarbonate diol are shown in Table 1. This polycarbonate diol is referred to as PC9.

[Polymerized diol polymerization example 10]
Using the same apparatus as in Polymerization Example 1, 430 g (4.8 mol) of dimethyl carbonate and 590 g (5.0 mol) of 1,6-hexanediol were charged. Titanium tetrabutoxide 0.09 g was added as a catalyst, and the reaction was carried out under the same conditions as in Polymerization Example 1. The results of analyzing the obtained polycarbonate diol are shown in Table 1. This polycarbonate diol is referred to as PC10.

[Polymerized diol polymerization example 11]
Using the same apparatus as in Polymerization Example 1, 460 g (5.1 mol) of dimethyl carbonate, 260 g (2.5 mol) of 1,5-pentanediol, and 280 g (2.4 mol) of 1,6-hexanediol were charged. Titanium tetrabutoxide 0.09 g was added as a catalyst, heated and stirred at a temperature of 140 to 150 ° C. under normal pressure, and reacted for 5 hours while distilling off the resulting mixture of ethanol and diethyl carbonate. Thereafter, the reaction temperature was 150 ° C. to 210 ° C., the pressure was 9 to 15 kPa, and the reaction was carried out for 5 hours while distilling off the resulting mixture of ethanol and diethyl carbonate. Then, it was made to react at 210 degreeC for 6 hours, reducing pressure gradually to 0.5kPa. The results of analyzing the obtained polycarbonate diol are shown in Table 1. This polycarbonate diol is referred to as PC11.

[Polymerized diol polymerization example 12]
The same 1,5-pentanediol and 1,6-hexanediol as in Polymerization Example 8 were used. Using the same apparatus as in Polymerization Example 1, 450 g (5.1 mol) of ethylene carbonate, 260 g (2.5 mol) of 1,5-pentanediol, and 310 g (2.6 mol) of 1,6-hexanediol were charged. 0.10 g of titanium tetrabutoxide was added as a catalyst, and the mixture was stirred and heated at normal pressure. The reaction temperature was 150 ° C. to 190 ° C., the pressure was 3.0 to 5.0 kPa, and the reaction was carried out for 15 hours while distilling off the resulting mixture of ethylene glycol and ethylene carbonate. Thereafter, the pressure was reduced to 0.5 kPa, and the reaction was further continued at 190 ° C. for 8 hours while distilling off ethylene carbonate and diol. The results of analyzing the obtained polycarbonate diol are shown in Table 1. This polycarbonate diol is referred to as PC12.

[Example 1]
In a reaction vessel equipped with a reflux condenser, a thermometer, and a stirrer, 200 g of polycarbonate diol (hereinafter referred to as PCD) PC1, 66.2 g of isophorone diisocyanate (hereinafter referred to as IPDI), triethylamine (hereinafter referred to as TMA). 23.3 g of dimethylolpropionic acid (hereinafter referred to as DMPA) neutralized with 700 g of methyl ethyl ketone (hereinafter referred to as MEK) was added and reacted at 50 ° C. for 2 hours. The urethane prepolymer was obtained. After the temperature in the reaction vessel was set to 30 ° C., 640 g of distilled water was added to the urethane prepolymer at a rate of 20 g / min while stirring to obtain an emulsion of a urethane prepolymer solution. Further, 23.8 g of a 20 wt% aqueous solution of ethylenediamine (hereinafter referred to as EDA) as a chain extender was added over 30 minutes with stirring. Thereafter, the temperature in the reaction vessel was set to 40 ° C., and the reaction was further continued for 30 minutes. After changing the reflux condenser to a simple distillation apparatus, MEK as a solvent was distilled off while raising the internal temperature of the reaction vessel to 80 ° C. under reduced pressure over 3 hours, and the solid content was about 30% by weight. A water-dispersed polyurethane resin (average particle size: 96 nm) was obtained. This water-dispersed polyurethane resin is referred to as PUD1.

[Examples 2 to 8]
In each of Examples 2 to 8, a water-dispersed polyurethane resin was obtained in the same manner as in Example 1 using PC2 to PC8 as the polycarbonate diol under the conditions shown in Table 2. Each of the water-dispersed polyurethane resins is referred to as PUD2 to PUD8.
In Example 7, since the prepolymer viscosity became high, MEK as a solvent was added and 1.5 times the predetermined amount shown in Table 2 was used.

[Comparative Examples 1-4]
In each of Comparative Examples 1 to 4, water-dispersed polyurethane resin was obtained in the same manner as in Example 1 using PC9 to 12 as polycarbonate diol under the conditions shown in Table 2. Each water-dispersed polyurethane resin is called PUD9-12.

  Regarding PUD 1 to 12, sample films were formed by the method shown in 5) above, and mechanical strength, elongation at break, flexibility and oil resistance were evaluated. The results are shown in Table 3 below.

  All of the examples of the present invention were found to have high mechanical strength and excellent balance between flexibility and oil resistance.

[Example 9]
90 g of water-dispersed polyurethane resin PUD1, 10 g of crosslinking agent (Duranate WB40-100, manufactured by Asahi Kasei Chemicals), 20 g of urethane beads (P800T, manufactured by Negami Kogyo), 10 g of carbon black (FW200P, manufactured by Degussa), light resistance To the water stabilizer (DIC-TBS, manufactured by DIC Corporation) 0.1 g, film-forming aid (NMP, manufactured by Kuraray Co., Ltd.) 5 g, ion-exchanged water is added so that the solid content concentration is 30%, A water-based coating composition was obtained by stirring. The coating composition was applied in the form of an ABS plate and cured by heating at 80 ° C. for 2 hours to obtain a coating film having a thickness of 40 to 50 μm. Using the obtained coating film, weather resistance, repairability and flexibility were evaluated, and the results are shown in Table 4 below.

[Examples 10 to 16, Comparative Examples 5 to 8]
In each of these Examples and Comparative Examples, water-based paint compositions were prepared by the method shown in Example 9 using water-dispersed polyurethane resins PUD2 to PUD12. A coating film was obtained by the method shown in Example 9 using the obtained water-based coating composition. Using the obtained coating film, weather resistance, repairability and flexibility were evaluated, and the results are shown in Table 4 below.

  All of the examples of the present invention were found to have good weather resistance, repairability and flexibility.

[Example 17]
Thickener (ASE-60, manufactured by Rohm & Haas) 20 g, carbon black (FW200P, manufactured by Degussa) 40 g, and titanium oxide (CR-93, manufactured by Ishihara Sangyo) 20 g were added to 30 g of ion-exchanged water and stirred. . Thereto, 10 g of a film-forming aid (NMP, manufactured by Kuraray Co., Ltd.), 80 g of an acrylic emulsion (Polytron Z330, manufactured by Asahi Kasei Chemicals Co., Ltd.), and 80 g of a water-dispersed polyurethane resin (PUD1) are added and stirred to prepare an aqueous coating composition. Obtained. This aqueous coating composition was spray-coated on a steel plate and cured by heating at 80 ° C. for 3 minutes to obtain a coating film having a thickness of 20 nm.

  The water-dispersible urethane prepolymer according to the present invention has an excellent balance of physical properties such as oil resistance, hydrolysis resistance, weather resistance, and flexibility, and can provide a coating film having good folding workability and self-repairability. It can utilize suitably for the use of a coating composition.

Claims (3)

A water dispersible urethane prepolymer which is a reaction product of (a) an organic isocyanate, (b) a polycarbonate diol, and (c) a compound having one hydrophilic center and at least two isocyanate-reactive groups, The polycarbonate diol (b) is a polycarbonate diol having a repeating unit represented by the following formula (A) and a terminal hydroxyl group, and 60 to 100 mol% of the repeating unit represented by the formula (A) is: It is a repeating unit represented by the formula (B) or the following formula (C), and the ratio of the repeating unit represented by the formula (B) and the repeating unit represented by the formula (C) is 70:30 to 30: The water-dispersible urethane prepolymer as described above, which is 70 (molar ratio) and has a primary terminal OH ratio of 95 to 99.5%.

  A water-dispersed polyurethane resin which is a reaction product of the water-dispersible urethane prepolymer of claim 1 and a chain extender and has an average particle size of 10 to 1000 nm.   A water-based paint composition comprising the water-dispersed polyurethane resin according to claim 2.