JP6555262B2 - Aqueous polyurethane resin dispersion - Google Patents

Description

  The present invention relates to an aqueous polyurethane resin dispersion in which a polyurethane resin is dispersed in an aqueous medium. The present invention also relates to a coating composition containing the aqueous polyurethane resin dispersion and a polyurethane resin film obtained by heating and drying the composition containing the polyurethane resin dispersion.

  The water-based polyurethane resin dispersion is an environmentally friendly material that can provide a coating film having adhesiveness, abrasion resistance, rubber-like properties, and the like, and can reduce volatile organic substances compared to conventional organic solvent-based polyurethane. Therefore, it is a material that is being replaced by organic solvent-based polyurethane. Polyether polyol is a useful compound used as a raw material for polyurethane resin, and a polyurethane resin used for rigid foam, flexible foam, thermoplastic elastomer, microcellular and the like can be produced by reaction with an isocyanate compound. It has been described that a polyurethane resin using a polyether polyol is superior in a low-temperature flexibility property to a polyurethane resin using a polyester polyol or a polycarbonate polyol (see Non-Patent Document 1). In addition, coating films obtained by applying an aqueous polyurethane resin dispersion using polyether polyol as a raw material are also known to have durability such as adhesion to a substrate, resistance to moist heat and hydrolysis. (See Patent Document 1).

  As described above, the aqueous polyurethane resin dispersion using the polyether polyol exhibits good characteristics, but is not sufficient as compared with the organic solvent-based polyurethane. In particular, since the drying property of the coating film is high, it was difficult to re-disperse the film once applied to the base material and remove it. By the aqueous polyurethane resin dispersion having a specific amount of a blocked isocyanato group having a urethane bond, a urea bond, and a carbonate bond by the present inventors, the film forming speed after coating is controlled, Re-dispersion in water is possible, and the coating film obtained by applying and heat-treating it has excellent water resistance and solvent resistance, excellent adhesion to the electrodeposition coating film, It has been found that since the breaking energy is high, the impact resistance is also excellent (see Patent Document 2).

  By using polyamines having three or more amino groups and / or imino groups in the molecule as a chain extender in the aqueous polyurethane resin dispersion, the present inventors can increase the swelling rate in an aqueous cleaning solution. (See Patent Document 3).

International Publication No. 2012/017724 International Publication No. 2010/098316 International Publication No. 2012/1665569

"Latest polyurethane materials and applied technology" Issued by CM Publishing Co., Ltd. Chapter 1 Chapter 2 Pages 23-32, Volume 2 Chapter 2 Pages 145-155

  When the aqueous polyurethane resin dispersion is used as a film, paint, or coating material, it is applied to a substrate or the like using an application device such as a bar coater, roll coater, or air spray. A coating film is formed on the substrate by heating and drying the applied aqueous polyurethane resin dispersion. Moreover, when providing a multiple layer coating film, an aqueous coating material may be further apply | coated on an aqueous coating film. However, when the aqueous coating material is applied on the aqueous coating material, the surface smoothness of the laminated coating film may be lowered when the water resistance of the coating film is low.

  Moreover, in the conventional water-based polyurethane resin dispersion which can recoat a coating film, sufficient adhesiveness to a base material and the big breaking energy in a tension | tensile_strength may not be obtained. In particular, a material having a low elastic modulus at a low temperature suitable for use in a cold region and a high breaking energy has been demanded. The coating film obtained using the aqueous polyurethane resin dispersion described in Patent Document 2 has a problem that the coating film is easily cracked when used in a cold region because of its high elastic modulus at low temperatures. . The coating film obtained using the aqueous polyurethane resin dispersion described in Patent Document 3 has problems such as being easily cracked at low temperatures.

  The problem of the present invention is that when a film is formed on a substrate, the elastic modulus in tension at a low temperature of −20 ° C. is low, and it is possible to achieve a large breaking energy and excellent adhesion to an electrodeposition coating film. It is to provide an aqueous polyurethane resin dispersion. Furthermore, the subject of this invention is providing the water-based polyurethane resin dispersion which gives the coating film with the low water swelling rate and the high swelling rate to an aqueous cleaning liquid.

The present invention has been made to solve the above problems, and specifically has the following configuration.
[1] Blocking of (a) a polyisocyanate compound, (b) a polyol compound, (c) an acidic group-containing polyol compound, (d) a hydroxyalkanoic acid, and optionally (e) an isocyanato group dissociating at 80 to 180 ° C. A polyurethane resin obtained by reacting (A) a polyurethane prepolymer obtained by reacting an agent and (B) a chain extender having reactivity to the isocyanato group of the polyurethane prepolymer is dispersed in an aqueous medium. An aqueous polyurethane resin dispersion,
The (b) polyol compound includes a polyether polyol having a number average molecular weight of 800 to 3,500,
The (B) chain extender includes a polyamine compound having a total of 3 or more amino groups and / or imino groups in one molecule,
The polyurethane resin has a total content of urethane bonds and urea bonds of 6 to 20% by weight based on solid content, and a content ratio of ester bonds and / or carbonate bonds of 10% by weight based on solid content. An aqueous polyurethane resin dispersion having a weight average molecular weight of 50,000 or more.
[2] The aqueous polyurethane resin dispersion according to [1], wherein the acid value of the polyurethane resin is 10 to 40 mg KOH / g, and the acid value derived from the molecular terminal of the polyurethane resin is 3 to 30 mg KOH / g.
[3] The aqueous polyurethane resin dispersion according to [1] or [2], wherein (a) the polyisocyanate compound is an alicyclic diisocyanate.
[4] The aqueous polyurethane resin dispersion according to any one of [1] to [3], wherein (d) the hydroxyalkanoic acid has 2 to 30 carbon atoms.
[5] The aqueous polyurethane resin dispersion according to any one of [1] to [4], wherein the content of the alicyclic structure in the polyurethane resin is 6 to 30% by weight based on the solid content.
[6] The aqueous polyurethane according to any one of [1] to [5], wherein (e) the blocking agent is at least one selected from the group consisting of oxime compounds, pyrazole compounds and malonic ester compounds. Resin dispersion.
[7] A coating material composition comprising the aqueous polyurethane resin dispersion according to any one of [1] to [6].
[8] A polyurethane resin film produced by heating and drying a composition containing the aqueous polyurethane resin dispersion according to any one of [1] to [6].

  According to the present invention, when a film is formed on a substrate, a water-based polyurethane resin capable of achieving a low elastic modulus, a large breaking energy and excellent adhesion to an electrodeposition coating film at a low temperature of −20 ° C. A dispersion can be provided. The present invention can also provide an aqueous polyurethane resin dispersion that provides a coating film having a low water swelling rate and a high swelling rate in an aqueous cleaning solution.

  In this specification, the numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. Further, the amount of each component in the composition means the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition.

[Aqueous polyurethane resin dispersion]
The aqueous polyurethane resin dispersion comprises (a) a polyisocyanate compound, (b) a polyol compound, (c) an acidic group-containing polyol compound, (d) a hydroxyalkanoic acid, and optionally (e) an isocyanato that dissociates at 80-180 ° C. A polyurethane resin obtained by reacting (A) a polyurethane prepolymer obtained by reacting a group blocking agent with (B) a chain extender having reactivity with an isocyanate group of the polyurethane prepolymer is an aqueous medium. An aqueous polyurethane resin dispersion dispersed therein,
The (b) polyol compound contains a polyether polyol having a number average molecular weight of 800 to 3,500,
The (B) chain extender includes a polyamine compound having a total of 3 or more amino groups and / or imino groups in one molecule,
The polyurethane resin has a total content of urethane bonds and urea bonds of 6 to 20% by weight based on solid content, and a content ratio of ester bonds and / or carbonate bonds of less than 10% by weight based on solid content. And the weight average molecular weight is 50,000 or more.

  Since the coating film obtained using the aqueous polyurethane resin dispersion has high adhesion to the electrodeposition coating film, it can be used as a protective coating for steel sheets. Furthermore, it has a high swelling ratio in an aqueous cleaning solution (for example, an aqueous solution containing alcohol, amine, amino alcohol, cellosolve, etc.) and can be repainted. The polyurethane resin film of the present invention can also be used as a decorative film.

[(A) polyisocyanate compound]
(A) The polyisocyanate compound is not particularly limited as long as it is a compound having two or more isocyanate groups, and is an aromatic polyisocyanate compound, a linear or branched aliphatic polyisocyanate compound, and an alicyclic polyisocyanate compound. Any of these may be used.

  Aromatic polyisocyanate compounds include 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate (TDI), 2,6-tolylene diisocyanate, metaxylylene diisocyanate (XDI), 4, 4'-diphenylenemethane diisocyanate (MDI), 2,4-diphenylmethane diisocyanate, 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'- Examples include dimethyl-4,4′-diisocyanatodiphenylmethane, 1,5-naphthylene diisocyanate, m-isocyanatophenylsulfonyl isocyanate, and p-isocyanatophenylsulfonyl isocyanate.

  Linear or branched aliphatic polyisocyanate compounds are ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethyl. Hexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethyl caproate, bis (2-isocyanatoethyl) fumarate, bis (2-isocyanatoethyl) carbonate, 2-isocyanatoethyl-2,6-diisocyanate And natohexanoate.

The alicyclic polyisocyanate compound is not particularly limited as long as it is a compound having an alicyclic structure. Isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene. Diisocyanate (hydrogenated TDI), 1,3-isocyanatomethylcyclohexane (hydrogenated XDI), bis (2-isocyanatoethyl) -4-dichlorohexene-1,2-dicarboxylate, 2,5-norbornane diisocyanate, 2, And alicyclic polyisocyanate compounds such as 1,6-norbornane diisocyanate.
(A) A polyisocyanate compound may be used individually by 1 type, and may use multiple types together.

  (A) The polyisocyanate compound is preferably an alicyclic polyisocyanate compound, more preferably an alicyclic diisocyanate compound, and particularly preferably 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI) and isophorone diisocyanate (IPDI). (A) When the polyisocyanate compound is an alicyclic polyisocyanate compound, preferably an alicyclic diisocyanate compound, it is possible to obtain a coating film that is less susceptible to yellowing, and the resulting coating film has a higher breaking energy. Tend. (A) When the polyisocyanate compound is 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI) and / or isophorone diisocyanate (IPDI), the reactivity is easy to control, and the resulting coating film has high breaking energy, water The swelling rate tends to be low.

[(B) Polyol compound]
The (b) polyol compound is a polyol compound that does not contain one or more acidic groups, including (b-1) a polyether polyol having a number average molecular weight of 800 to 3,500. That is, the (b) polyol compound is a polyol compound other than a polyether polyol having a number average molecular weight of 800 to 3,500 and containing no acidic group (hereinafter referred to as “(b-2) other polyol compound”. May also be included). (B) The polyol compound preferably does not contain a polycarbonate polyol. (B) The polyol compound consists only of (b-1) a polyether polyol having a number average molecular weight of 800 to 3,500, or (b-1) a polyether polyol having a number average molecular weight of 800 to 3,500. It is more preferable that it consists only of multiple types of polyether polyols.

[(B-1) polyether polyol having a number average molecular weight of 800 to 3,500]
(B-1) A polyether polyol having a number average molecular weight of 800 to 3,500 (hereinafter also referred to as “component (b-1)”) has a number average molecular weight of 800 to 3,500 and an acidic group. If it is a polyether polyol which does not contain, it will not specifically limit. When the number average molecular weight of the polyether polyol is less than 800, there are problems such as low breaking energy in tension of the obtained coating film. When the number average molecular weight of the polyether polyol is more than 3,500, there is a problem that the obtained aqueous polyurethane resin dispersion is inferior in film forming property. The number average molecular weight of the component (b-1) is more preferably 1,500 to 3,200, and even more preferably 2,000 to 3,000, from the viewpoint of breaking energy and film-forming property in the coating film tension. When two or more kinds of polyether polyols having different molecular weights are used in combination, the number average molecular weight when the polyether polyols used in combination are mixed is preferably within this range.

  (B) The proportion of the component (b-1) in the total weight of the polyol compound is preferably 50 to 100% by weight, and 70 to 100% by weight from the viewpoint of breaking energy in the tension of the coating film. Is more preferable, and 85 to 100% by weight is particularly preferable.

In this specification, the number average molecular weight (Mn) of polyether polyol is calculated | required by following Formula from a hydroxyl value.
Mn = (56,100 × valence) / hydroxyl value In the formula, the valence is the number of hydroxyl groups in one molecule, and the hydroxyl value is a value measured in accordance with the method B of JIS K1557. When the polyether polyol is a polyether diol, the valence is 2.

  The specific structure of the component (b-1) is not particularly limited as long as the number average molecular weight is 800 to 3,500. Polyethylene glycol, poly (1,2-propylene glycol), poly (1,3-propylene) Glycol), poly (1,3-tetramethylene glycol), poly (1,4-tetramethylene glycol), poly (1,6-hexamethylene glycol), random copolymers and block copolymers of ethylene oxide and propylene oxide And a random copolymer or block copolymer of ethylene oxide and butylene oxide. Poly (1,4-tetramethylene glycol) is preferable in that the water swelling rate is low. These may be used alone or in combination.

[(B-2) Other polyol compounds]
(B-2) Other polyol compounds will not be specifically limited if it is a polyol compound which does not contain an acidic group. (B-2) Other polyol compounds include aliphatic diol, alicyclic diol, aromatic diol, polyfunctional polyol, polyether polyol other than number average molecular weight of 800 to 3,500, polyester polyol, polycarbonate polyol, polyester Polycarbonate polyol, polyether polyester polyol, polyether polycarbonate polyol and the like can be mentioned.

  Aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-pentanediol, 1,8-octanediol, Linear aliphatic diols such as 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol; 1,3-butanediol, 3-methylpentane-1,5-diol, 2- Examples include branched aliphatic diols such as ethylhexane-1,6-diol, 2-methyl-1,3-pentanediol, neopentyl glycol, and 2-methyl-1,8-octanediol. The alicyclic diol includes 1,3-cyclohexanediol, 1,4-cyclohexanediol, 2,2′-bis (4-hydroxycyclohexyl) propane, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol and the like. Is mentioned. Examples of the aromatic diol include 1,4-benzenedimethanol. Examples of the polyfunctional polyol include trimethylolpropane and pentaerythritol.

  (B-2) The other polyol compound is preferably an aliphatic diol, an alicyclic diol, or a polyether polyol having a number average molecular weight other than 800 to 3,500. Here, (b-2) the other polyol compound does not include the later-described (c) acidic group-containing polyol compound.

[(C) Acid group-containing polyol compound]
(C) The acidic group-containing polyol compound is not particularly limited as long as it is a compound having at least one acidic group and two or more hydroxy groups. Examples of the acidic group include a carboxy group and a sulfo group. The acidic group-containing polyol compound is preferably an acidic group-containing diol compound, and more preferably an acidic group-containing diol compound having 5 to 8 carbon atoms. (C) The acidic group-containing polyol compound is 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, N, N-bishydroxyethylglycine, N, N-bishydroxyethylalanine, 3,4- Examples include dihydroxybutane sulfonic acid and 3,6-dihydroxy-2-toluene sulfonic acid. (C) One type of acidic group-containing polyol compound may be used alone, or a plurality of types may be used in combination. (C) The acidic group-containing polyol compound is preferably a dimethylol alkanoic acid having 4 to 12 carbon atoms containing two methylol groups from the viewpoint of availability and reactivity, and 2,2-dimethylolpropionic acid and More preferred is 2,2-dimethylolbutanoic acid.

[(D) Hydroxyalkanoic acid]
(D) Hydroxyalkanoic acid is not particularly limited as long as it is a compound having one carboxyl group and one hydroxyl group in one molecule. (D) The number of carbon atoms of the hydroxyalkanoic acid is preferably 2-30, more preferably 6-30, and particularly preferably 10-26. (D) When the number of carbon atoms of the hydroxyalkanoic acid is from 2 to 30, the water swelling rate of the resulting polyurethane film tends to be low, and the adhesion to the electrodeposited surface tends to be high. (D) Hydroxyalkanoic acid is glycolic acid (2-hydroxyacetic acid), 3-hydroxybutyric acid, 4-hydroxybutyric acid, 10-hydroxydecanoic acid, hydroxypivalic acid (2,2-dimethyl-3-hydroxypropionic acid) , 12-hydroxy dodecanoic acid, 16-hydroxy hexadecanoic acid, milk acid, 3-hydroxypropionic acid, 2-hydroxy octanoic acid, 3-hydroxy undecanoic acid, 12-hydroxystearic acid, and 12-hydroxystearic oleic acid. Glycolic acid, 4-hydroxybutyric acid, hydroxypivalic acid, and 12-hydroxystearic acid are preferred. In view of lowering the water swelling rate of the resulting polyurethane film, (d) hydroxyalkanoic acid is particularly preferably 12-hydroxystearic acid. (D) Hydroxyalkanoic acid may be used individually by 1 type, and may use multiple types together.

[(E) Blocking agent for isocyanato group dissociating at 80 to 180 ° C.]
(E) Isocyanate group blocking agent that dissociates at 80 to 180 ° C. (hereinafter, also referred to as “(e) blocking agent”) is not particularly limited as long as it is a compound that dissociates from an isocyanate group at 80 to 180 ° C. . The “blocking agent” means a compound that can react with an isocyanato group to convert the isocyanato group into another group and can be reversibly converted from the other group to the isocyanato group by heat treatment. (E) The blocking agent is a malonic acid ester compound, preferably a malonic acid diester compound such as dimethyl malonate or diethyl malonate; a pyrazole compound such as 1,2-pyrazole or 3,5-dimethylpyrazole; 1 Oxime compounds such as 2,4-triazole and methyl ethyl ketoxime; diisopropylamine, caprolactam and the like. (E) The blocking agent is preferably at least one selected from the group consisting of an oxime compound, a pyrazole compound and a malonic ester compound from the viewpoint of the dissociation temperature. (E) The blocking agent is more preferably a pyrazole-based compound and particularly preferably 3,5-dimethylpyrazole from the viewpoint of high storage stability and low-temperature thermal cross-linking property. (E) A blocking agent may be used alone or in combination of two or more.

[(A) Polyurethane prepolymer]
(A) The polyurethane prepolymer comprises (a) a polyisocyanate compound, (b) one or more polyol compounds including a polyether polyol having a number average molecular weight of 800 to 3,500, (c) an acidic group-containing polyol compound, ( d) A polyurethane prepolymer obtained by reacting a hydroxyalkanoic acid and optionally (e) a blocking agent of an isocyanato group which dissociates at 80 to 180 ° C. The method for producing the polyurethane prepolymer is not particularly limited, and examples thereof include the following methods.

The first method performs a urethanization reaction by reacting (a) a polyisocyanate compound, (b) a polyol compound, and (c) an acidic group-containing polyol compound in the presence or absence of a urethanization catalyst. Thereafter, (d) a hydroxyalkanoic acid is reacted to synthesize a polyurethane prepolymer (A).
In the second method, a urethanization reaction is performed by reacting (a) a polyisocyanate compound, (b) a polyol compound, and (c) an acidic group-containing polyol compound in the presence or absence of a urethanization catalyst. Then, (d) the hydroxyalkanoic acid is reacted, and finally (e) the blocking agent is reacted in the presence or absence of the blocking catalyst to perform the blocking reaction, and a part of the terminal isocyanate group is blocked. (A) A method for synthesizing a polyurethane prepolymer.
In the third method, (a) a polyisocyanate compound and (e) a blocking agent are reacted in the presence or absence of a blocking catalyst to perform a blocking reaction, thereby blocking a part of the isocyanate group. The polyisocyanate compound was synthesized and reacted with (b) a polyol compound and (c) an acidic group-containing polyol compound in the presence or absence of a urethanization catalyst. d) A method of synthesizing (A) a polyurethane prepolymer by reacting with a hydroxyalkanoic acid.

  Urethane catalyst is not particularly limited, and salts of metals and organic and inorganic acids such as tin-based catalysts (trimethyltin laurate, dibutyltin dilaurate, etc.), lead-based catalysts (lead octylate, etc.), organometallic derivatives, amines Examples thereof include system catalysts (triethylamine, N-ethylmorpholine, triethylenediamine, etc.), diazabicycloundecene catalysts, and the like. The urethanization catalyst is preferably dibutyltin dilaurate from the viewpoint of reactivity. The blocking catalyst is not particularly limited, and examples thereof include alkaline catalysts such as dibutyltin dilaurate and sodium methoxide. The conditions for the urethanation reaction and the blocking reaction are not particularly limited, and can be appropriately selected according to the reactivity of the components used. For example, the conditions for the urethanization reaction can be 3 to 15 hours at a temperature of 50 to 100 ° C. The conditions for the blocking reaction can be 1 to 5 hours at a temperature of 50 to 100 ° C. The urethanization reaction and the blocking reaction may be performed independently or continuously.

[(B) Chain extender]
(B) The chain extender includes (B-1) a polyamine (hereinafter also referred to as “(B-1) polyamine”) having three or more amino groups and / or imino groups in total in one molecule. (B) The chain extender may contain (B-2) other chain extender in addition to (B-1) polyamine.

  (B-1) Polyamine is, for example, a triamine compound such as diethylenetriamine, bis (2-aminopropyl) amine, bis (3-aminopropyl) amine; triethylenetetramine, tripropylenetetramine, N- (benzyl) triethylenetetramine N, N ′ ″-(dibenzyl) triethylenetetramine, tetramine compounds such as N- (benzyl) -N ′ ″-(2-ethylhexyl) triethylenetetramine; tetraethylenepentamine, tetrapropylenepentamine, etc. Examples include pentamine compounds; hexamine compounds such as pentaethylenehexamine and pentapropylenehexamine; and polyamine compounds such as polyethyleneimine and polypropyleneimine. (B-1) Polyamine is diethylenetriamine, triethylenetetramine, bis (2-aminopropyl) amine, bis (3-aminopropyl) amine, tripropylenetetramine, tetraethylenepenta, from the viewpoint of reactivity with the polyurethane prepolymer. Preferred are polyamines having two amino groups and one or more imino groups, such as amine, tetrapropylenepentamine, pentaethylenehexamine, and pentapropylenehexamine. (B-1) A polyamine may be used individually by 1 type, and may use multiple types together.

  (B-2) Other chain extenders include, for example, hydrazine, ethylenediamine, 1,4-tetramethylenediamine, 2-methyl-1,5-pentanediamine, 1,6-hexamethylenediamine, 1,4-hexa. Diamine compounds such as methylenediamine, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, 1,3-bis (aminomethyl) cyclohexane, xylylenediamine, piperazine, 2,5-dimethylpiperazine; 1,4- Examples include polyol compounds such as butanediol and 1,6-hexanediol; water and the like. (B-2) The other chain extender is preferably a diamine compound. (B-2) Another chain extender may be used individually by 1 type, and may use multiple types together.

  (B) The content of the (B-1) polyamine compound in the chain extender is preferably 10 to 100 mol%, more preferably 20 to 100 mol%, and 30 to 100 mol%. It is particularly preferred.

  The amount of the (B) chain extender is preferably equal to or less than the equivalent of the unblocked isocyanato group that becomes the chain extension origin in the (A) polyurethane prepolymer, and more preferably the amount of the unblocked isocyanato group. 0.7 to 0.99 equivalents. (B) When the amount of the chain extender is equal to or less than the equivalent of the unblocked isocyanato group, preferably 0.99 equivalent or less, the molecular weight of the chain-extended polyurethane resin tends to be suppressed. The strength of the coating film obtained by applying the obtained aqueous polyurethane resin dispersion tends to be further improved.

[Method for producing aqueous polyurethane resin dispersion]
The manufacturing method in particular of an aqueous polyurethane resin dispersion is not restrict | limited, The following method is mentioned. The production method of the non-restricted aqueous polyurethane resin dispersion includes (a) a polyisocyanate compound, (b) a polyol compound, (c) an acidic group-containing polyol compound, (d) a hydroxyalkanoic acid, and optionally (e) a blocking agent. A step of reacting to obtain a polyurethane prepolymer, a step of neutralizing acidic groups in the polyurethane prepolymer, a step of dispersing the polyurethane prepolymer in an aqueous medium, and a reaction of (B) a chain extender to the polyurethane prepolymer. A step of obtaining an aqueous polyurethane resin dispersion.

  In the method for producing an aqueous polyurethane resin dispersion, the step of obtaining a polyurethane prepolymer includes the above-described method for producing a polyurethane prepolymer. In the method for producing an aqueous polyurethane resin dispersion, the step of neutralizing acidic groups and the step of dispersing the polyurethane prepolymer in an aqueous medium may be performed separately or together. In the method for producing an aqueous polyurethane resin dispersion, the step of reacting the polyurethane prepolymer with the (B) chain extender may be after the step of dispersing the polyurethane prepolymer in the aqueous medium, and the polyurethane prepolymer in the aqueous medium. You may carry out with the process to disperse | distribute. Each step in the method for producing an aqueous polyurethane resin dispersion may be performed in an inert gas atmosphere or in the air.

  In the aqueous polyurethane resin dispersion, the total content of urethane bonds and urea bonds in the aqueous polyurethane resin dispersion is 6 to 20% by weight and 7 to 15% by weight based on the solid content. Is preferably 7.5 to 13.5% by weight, more preferably 8 to 13% by weight. Here, the content ratio of the urethane bond means the content ratio of the urethane bond unit (-NHCOO-) in the solid content of the polyurethane resin, and the content ratio of the urea bond means the urea bond unit (in the solid content of the polyurethane resin ( -NHCONH-) means the content ratio. If the total content of urethane bonds and urea bonds is less than 6% by weight, the coating film cannot be sufficiently formed, and the coating film surface becomes sticky after drying. In addition, when the total content of urethane bonds and urea bonds exceeds 20% by weight, when the aqueous polyurethane resin dispersion is applied to a substrate, the redispersibility of the paint or coating film in an aqueous solvent may be reduced. Since it is inferior, removal becomes difficult and repainting may not be possible.

  The urethane bond content in the aqueous polyurethane resin dispersion is not particularly limited as long as the sum of the urea bond content and the urea bond content is 6 to 20% by weight based on the solid content. The content of urethane bonds in the aqueous polyurethane resin dispersion is preferably 4 to 15% by weight, more preferably 5 to 12% by weight, and 6 to 10% by weight based on the solid content. Particularly preferred. The content of urea bonds in the aqueous polyurethane resin dispersion is not particularly limited as long as the sum of the content of urethane bonds and the content of urethane bonds is 6 to 20% by weight based on the solid content. The urea bond content in the aqueous polyurethane resin dispersion is preferably 1 to 6% by weight, more preferably 1.5 to 5% by weight, and 2 to 4.5% by weight based on the solid content. More preferably. Here, the content ratio of the urethane bond and the content ratio of the urea bond in the aqueous polyurethane resin dispersion can be calculated from the charged amounts of the respective components when the aqueous polyurethane resin dispersion is prepared. It can also be calculated from the infrared absorption spectrum of the coating film.

  In the aqueous polyurethane resin dispersion, the content ratio of the isocyanate group to which the blocking agent is bonded (also referred to as blocked isocyanate group) is not particularly limited, but is 2.0% by weight or less in terms of solid content and in terms of isocyanate group. Preferably, it is 1.5% by weight or less, more preferably 1.2% by weight or less, and particularly preferably 1.0% by weight or less. Here, the content ratio of the isocyanate group to which the blocking agent is bonded is calculated by calculating the content ratio of the isocyanate group to which the blocking agent is bonded in the solid content of the polyurethane resin as the content ratio of the isocyanate group (-NCO). means. The content ratio of the isosinato group to which the blocking agent is bonded in the aqueous polyurethane resin dispersion can be calculated from the amount of each component charged when preparing the aqueous polyurethane resin dispersion. When the content ratio of the isocyanate group to which the blocking agent is bonded is 2.0% by weight or less, the elongation at break of the obtained coating film becomes higher and a coating film resistant to impact can be obtained.

  In the aqueous polyurethane resin dispersion, the content of ester bonds and / or carbonate bonds in the aqueous polyurethane resin dispersion is preferably less than 10% by weight and more preferably less than 7% by weight based on the solid content. More preferably, it is wt%, particularly preferably 0 wt%. Here, the content ratio of the ester bond means the content ratio of the ester bond unit (—COO—) in the solid content of the polyurethane resin, and the content ratio of the carbonate bond means the carbonate bond in the solid content of the polyurethane resin. It means the content ratio of units (—OCOO—). The content rate of the ester bond and / or carbonate bond in the aqueous polyurethane resin dispersion can be calculated from the charged amounts of the respective components when preparing the aqueous polyurethane resin dispersion. It can also be calculated from the infrared absorption spectrum of the coating film. When the content ratio of the ester bond and / or the carbonate bond exceeds 10% by weight, there is a problem that the elastic modulus at low temperature is increased and the breaking energy is decreased.

  The weight average molecular weight of the polyurethane resin is 50,000 or more, preferably 70,000 or more, more preferably 90,000 or more, further preferably 120,000 or more, and 150,000. The above is particularly preferable. When the weight average molecular weight of the polyurethane resin is less than 50,000, the elongation at break of the obtained coating film becomes small, and a coating film resistant to impact cannot be obtained. When the weight average molecular weight of the polyurethane resin is 150,000 or more, there is a tendency that a coating film having a lower swelling rate in water and excellent in water resistance is obtained. In this specification, the weight average molecular weight is measured by gel permeation chromatography (GPC), and is a conversion value obtained from a standard curve of standard polystyrene prepared in advance.

Although the acid value of a polyurethane resin is not specifically limited, It is preferable that it is 10-40 mgKOH / g, It is more preferable that it is 13-35 mgKOH / g, It is especially preferable that it is 14-30 mgKOH / g. There exists a tendency for the dispersibility in an aqueous medium to improve that the acid value of a polyurethane resin is the range of 10-40 mgKOH / g.
The polyurethane resin preferably has an acid value derived from molecular terminals of 3 to 30 mgKOH / g, more preferably 4 to 25 mgKOH / g, and particularly preferably 5 to 15 mgKOH / g. When the acid value derived from the molecular end is in the range of 3 to 30 mg KOH / g, the swelling rate to the aqueous cleaning liquid tends to be high, and the adhesion to the electrodeposition coating film tends to be high.
Therefore, the acid value of the polyurethane resin is preferably 10 to 40 mgKOH / g, and the acid value derived from the molecular terminal of the polyurethane resin is preferably 3 to 30 mgKOH / g. In particular, when the acid value of the polyurethane resin is in the range of 14 to 30 mg KOH / g and the acid value derived from the molecular terminal is in the range of 5 to 15 mg KOH / g, the breaking energy of the coating film at a low temperature of −20 ° C. Can be high.
The acid value of the polyurethane resin is the sum of (c) the acid value derived from the acidic group-containing polyol and (d) the acid value derived from the hydroxyalkanoic acid. Moreover, the acid value derived from the molecular terminal of the polyurethane resin is the acid value derived from (d) hydroxyalkanoic acid.
The acid value of the aqueous polyurethane resin is a value measured according to the indicator titration method of JIS K1557. The acid value derived from the molecular end of the aqueous polyurethane resin is calculated based on the solid content based on the molar concentration of hydroxyalkanoic acid (mol / g) from the charged amount of each component when preparing the aqueous polyurethane resin dispersion. It is the value converted into the weight fraction (mgKOH / g) of potassium hydroxide required for neutralization.

  In the molecular terminal portion of the polyurethane resin, the molar ratio between the carboxy group and the isocyanate group to which the blocking agent is bonded (hereinafter also referred to as “terminal carboxy group / blocked NCO group”) is 10/90 to 70/30. Is preferable, 20/80 to 60/40 is more preferable, 30/70 to 60/40 is further preferable, and 30/70 to 49/51 is particularly preferable. In the terminal carboxy group / blocked NCO group, by reducing the number of moles of the terminal carboxy group relative to the number of moles of the blocked NCO group, a coating film that does not break (provided high breaking energy) unless higher energy is applied. An aqueous polyurethane resin dispersion can be obtained.

  The content of the alicyclic structure in the aqueous polyurethane resin dispersion is not particularly limited, but is preferably 6 to 30% by weight, more preferably 7 to 25% by weight, and 7 to 22 based on the solid content. It is more preferable that it is weight%, and it is especially preferable that it is 8-20 weight%. When the content of the alicyclic structure in the aqueous polyurethane resin dispersion is 6% by weight or more, the tensile strength of the coating film is increased and the breaking energy is increased. In addition, when the content of the alicyclic structure in the aqueous polyurethane resin dispersion is 30% by weight or less, when the obtained aqueous polyurethane resin dispersion is applied to a substrate, the paint or coating film is reconstituted in an aqueous solvent. Since the dispersibility is high, removal is easy and repainting is easier. For example, when the alicyclic structure is a cyclohexane ring, the content ratio of the alicyclic structure based on the solid content is a portion obtained by removing two hydrogen atoms from cyclohexane (the cyclohexane residue) in the solid content in the aqueous polyurethane resin dispersion. It shows how many groups are present.

〔Neutralizer〕
The aqueous polyurethane resin dispersion preferably contains a neutralizing agent as an optional component. The neutralizing agent is used to neutralize at least some of the acidic groups of the polyurethane prepolymer and disperse the polyurethane prepolymer in the aqueous medium. Here, the aqueous polyurethane resin dispersion containing a neutralizing agent is preferably obtained by reacting a polyurethane prepolymer dispersed in an aqueous medium with a chain extender. Neutralizing agents are trimethylamine, triethylamine, tri-n-propylamine, tributylamine, triethanolamine, aminomethylpropanol, aminomethylpropanediol, aminoethylpropanediol, trihydroxymethylaminomethane, monoethanolamine, N, N -Organic amines such as dimethylethanolamine and triisopropanolamine; inorganic alkali salts such as potassium hydroxide and sodium hydroxide; ammonia and the like. These may be used alone or in combination of two or more.

  From the viewpoint of workability, the neutralizing agent is preferably an organic amine, and more preferably triethylamine. The amount of the neutralizing agent is, for example, 0.4 to 1.2 equivalents, and preferably 0.6 to 1.0 equivalents per equivalent of acidic group in the aqueous polyurethane resin dispersion.

[Optional ingredients]
The aqueous polyurethane resin dispersion may contain amino alcohol, monoalcohol and monoamine as further optional components. For example, a polyurethane prepolymer containing a hydroxyl group at the molecular end can be obtained by reacting the polyurethane prepolymer with amino alcohol in a state where the polyurethane prepolymer is dispersed in water. Thereby, the swelling rate to an aqueous cleaning liquid can be adjusted. Examples of the amino alcohol include ethanolamine, butanolamine, hexanolamine and the like, and ethanolamine is preferable from the viewpoint of water dispersibility. The amount of amino alcohol added is preferably less than 2% by weight, more preferably less than 1% by weight, based on the solid content of the aqueous polyurethane resin dispersion.

  For example, (A) a polyurethane prepolymer having a molecular terminal nonreactive can be obtained by reacting a polyurethane prepolymer with a monoalcohol or monoamine in a state where the polyurethane prepolymer is dispersed in water. Thereby, a crosslinking degree can be adjusted and it becomes possible to control the elasticity modulus of a coating film. Examples of the monoalcohol include ethanol, n-propanol, isopropanol, n-butanol, hexanol, octanol and the like, and n-butanol is preferable from the viewpoint of ease of production. Examples of the monoamine include ethylamine, n-propylamine, isopropylamine, n-butylamine, n-hexylamine and the like. The amount of monoalcohol and monoamine added is preferably less than 2% by weight, more preferably less than 1% by weight, based on the solid content of the aqueous polyurethane resin.

  From the viewpoint of reactivity, the monoalcohol is preferably used in the production of the (A) polyurethane prepolymer. The monoamine is preferably used after (A) the polyurethane prepolymer is dispersed in an aqueous medium, and is preferably used before (B) the chain extender is added. (A) In the case of adding a monoalcohol during the production of the polyurethane prepolymer, it is preferable to carry out the reaction in a state heated to 60 ° C. or higher from the viewpoint of improving the reaction rate. When adding a monoamine, it is preferable to make it react in the state of 60 degrees C or less from the point which suppresses a side reaction.

[Aqueous medium]
The polyurethane resin is dispersed in an aqueous medium. Examples of the aqueous medium include water, a mixed medium of water and a hydrophilic organic solvent, and the like. Examples of water include clean water, ion-exchanged water, distilled water, and ultrapure water, but ion-exchanged water is preferable in view of availability and the fact that polyurethane resin particles become unstable due to the influence of salt.

  The hydrophilic organic solvent is a lower monohydric alcohol such as methanol, ethanol or propanol; a polyhydric alcohol such as ethylene glycol or glycerin; N-methylmorpholine, dimethyl sulfoxide, dimethylformamide, N-methylpyrrolidone or N-ethylpyrrolidone. And aprotic hydrophilic organic solvents such as dipropylene glycol dimethyl ether (DMM) and β-alkoxypropionic acid amide. The amount of the hydrophilic organic solvent in the aqueous medium is preferably 0 to 20% by weight, and more preferably 0 to 10% by weight.

[Coating film obtained by applying aqueous polyurethane resin dispersion]
The coating film obtained by applying the aqueous polyurethane resin dispersion is excellent in water resistance and solvent resistance, and is excellent in adhesion to the electrodeposition coating film. There are two types of electrodeposition coatings, anionic and cationic. Generally, the cationic type uses a modified epoxy resin as a base resin and is crosslinked with isocyanate, whereas the anionic type is crosslinked by oxidative polymerization. In the cationic type, the secondary hydroxyl group generated by the ring opening of the epoxy group remains, and in the anionic type, the carboxyl group is introduced. Therefore, in the heat drying process of the aqueous polyurethane resin dispersion of the present invention, the molecular end is derived. It is considered that the acid groups of the electrode are associated with the polar groups on the surface of the electrodeposition coating film to develop adhesiveness. Such electrodeposition coatings are used in industrial machinery such as heavy machinery and agricultural machinery, vehicles such as automobiles and bicycles, prefabricated steel frames, fire doors, building materials such as sashes, electrical equipment such as switchboards, elevators, and microwave ovens. Yes.

  The aqueous polyurethane resin dispersion can be applied, for example, on a base material on which an electrodeposition coating film is formed using an application device and baked at a temperature of 60 to 250 ° C. A drying step can be provided before the baking step, or baking can be performed at a time after the aqueous polyurethane resin dispersion is applied and dried, and another coating material is applied and dried.

[Coating material composition]
The coating material composition includes an aqueous polyurethane resin dispersion and optionally an additive. When the coating material composition does not contain an additive, the coating material composition consists only of an aqueous polyurethane resin dispersion. Additives include plasticizers, antifoaming agents, leveling agents, fungicides, rust inhibitors, matting agents, flame retardants, tackifiers, thixotropic agents, lubricants, antistatic agents, thickeners, thickeners , Diluents, pigments, dyes, ultraviolet absorbers, light stabilizers, antioxidants, fillers and the like. The coating material composition can be applied to coating (film formation) on various substrates such as metal, ceramic, synthetic resin, nonwoven fabric, woven fabric, knitted fabric, and paper.

[Polyurethane resin film]
A polyurethane resin film (hereinafter also referred to as “polyurethane film”) is produced by heating and drying a composition containing an aqueous polyurethane resin dispersion. The composition comprising the aqueous polyurethane resin dispersion comprises an aqueous polyurethane resin dispersion and optionally an additive. When the composition containing the aqueous polyurethane resin dispersion does not contain an additive, the composition containing the aqueous polyurethane resin dispersion consists only of the aqueous polyurethane resin dispersion. Examples of the additive include the components described above for the coating material.

  The method for producing the polyurethane resin film is not particularly limited, and a step of applying a composition containing an aqueous polyurethane resin dispersion on a releasable substrate, and drying the composition containing the aqueous polyurethane resin dispersion to form a polyurethane resin Examples thereof include a method including a step of forming a film and a step of peeling the releasable substrate and the polyurethane resin film.

  The peelable substrate is not particularly limited, and examples thereof include a glass substrate; a plastic substrate such as polyethylene terephthalate and polytetrafluoroethylene; and a metal substrate. The peelable substrate is obtained by treating the surface of each substrate with a release agent. The coating apparatus for applying the composition containing the aqueous polyurethane resin dispersion is not particularly limited, and examples thereof include a bar coater, a roll coater, a gravure roll coater, and an air spray.

  The thickness of the polyurethane resin film is not particularly limited, but is preferably 0.01 mm to 0.5 mm.

Next, the present invention will be described in more detail with reference to examples and comparative examples.
The physical properties were measured as follows.
(1) Hydroxyl value: Measured according to JIS K 1557 method B.
(2) Free isocyanate group content: 0.5 g of the reaction mixture after completion of the urethanization reaction was sampled and added to a mixed solution of 0.1 mL / L (liter) of dibutylamine-tetrahydrofuran (THF) solution and 10 mL of THF. Then, unconsumed dibutylamine was titrated with 0.1 mol / L hydrochloric acid. From the difference between the titration value and the blank experiment, the molar concentration of the isocyanate group remaining in the reaction mixture was calculated. The molar concentration was converted to the weight fraction of isocyanato groups to obtain the free isocyanate group content. The indicator used for titration is bromophenol blue.
(3) Acid value: 100 g of the aqueous polyurethane resin dispersion was diluted 10 times with pure water, and 10 g of acetic acid was mixed and stirred at room temperature. The precipitated solid was filtered with a 120 mesh stainless steel wire mesh. 600 g of water was poured into the obtained solid, stirred for 30 minutes at room temperature and allowed to stand, and then the solid was filtered through a 120-mesh stainless wire mesh. The same operation was repeated 5 times. After the remaining solid was dried at 60 ° C. for 24 hours, the acid value was measured according to the indicator titration method of JIS K 1557.
(4) The content ratio (urethane bond content) based on solid content of urethane bonds and the content ratio (urea bond content) based on solid content of urea bonds are determined based on the proportions of the raw materials of the aqueous polyurethane resin dispersion, The molar concentration (mole / g) of the urea bond was calculated and expressed as a weight fraction. The weight fraction was based on the solid content of the aqueous polyurethane resin dispersion. An aqueous polyurethane resin dispersion (0.3 g) was applied to a glass substrate with a thickness of 0.2 mm, and the weight remaining after heating and drying at 140 ° C. for 4 hours was measured. The partial concentration was used. The weight fraction was calculated using the product of the total weight of the aqueous polyurethane resin dispersion and the solid content concentration as the solid content weight.
(5) For the ester bond solid content content (ester bond content), the molar concentration (mol / g) of the ester bond is calculated from the charge ratio of each raw material of the aqueous polyurethane resin dispersion, and converted to a weight fraction. I wrote what I did. The weight fraction was calculated based on the solid content of the aqueous polyurethane resin dispersion by the same method as the content of the urethane bond based on the solid content.
(6) For the carbonate bond solid content basis content (carbonate bond content), the carbonate bond molar concentration (mol / g) is calculated from the charge ratio of each raw material of the aqueous polyurethane resin dispersion, and converted to the weight fraction. I wrote what I did. The weight fraction was calculated based on the solid content of the aqueous polyurethane resin dispersion by the same method as the content of the urethane bond based on the solid content.
(7) For the acid value derived from the molecular end (terminal acid value), the molar concentration (mol / g) of hydroxyalkanoic acid is calculated based on the solid content based on the charge ratio of each raw material of the aqueous polyurethane resin dispersion. Is converted to the weight fraction of potassium hydroxide required for neutralization (mgKOH / g).
(8) The content ratio (alicyclic structure content) based on the solid content of the alicyclic structure represents the weight fraction of the alicyclic structure calculated from the charging ratio of each raw material of the aqueous polyurethane resin dispersion. The weight fraction was calculated based on the solid content of the aqueous polyurethane resin dispersion by the same method as the content of the urethane bond based on the solid content.
(9) The weight average molecular weight of the polyurethane resin in the aqueous polyurethane resin dispersion was measured by gel permeation chromatography (GPC), and a conversion value obtained from a standard polystyrene calibration curve prepared in advance was described.
(10) The content ratio of the isocyanate group to which the blocking agent based on the solid content in the aqueous polyurethane resin dispersion is bonded (in terms of isocyanate group, blocked NCO content) is the weight of the isocyanate group charged in the charged molar amount of the blocking agent. The ratio divided by the solid content weight of the aqueous polyurethane resin dispersion was expressed. The solid content weight of the aqueous polyurethane resin dispersion was calculated by the same method as the content based on the solid content of the urethane bond.

(11) Swelling ratio of coating film in water: 0.3 mL of aqueous polyurethane resin dispersion was applied to a glass plate at a thickness of 72 μm (bar coater # 36) until the solid content concentration of the coating film reached 90%. Heat drying at 50 ° C. This coating film was immersed in ion exchange water at 28 ° C. for 2 hours, and the coating film weight before and after immersion was measured. The swelling ratio of the coating film into water was calculated by the following formula. The solid content concentration of the dried coating film was calculated by the same method as the content ratio of the urethane bond based on the solid content.
(Swelling ratio) = [(weight of coating film after water immersion) − (weight of coating film before water immersion)] / (weight of coating film before water immersion) × 100
(12) Swelling ratio of dry coating film to aqueous cleaning solution: Aqueous cleaning solutions containing 5%, 4%, 1% and 90% of butyl cellosolve, isopropanol, dimethylethanolamine and ion-exchanged water on a weight basis were prepared. . An aqueous polyurethane resin dispersion (0.3 mL) was coated on a glass plate at a thickness of 72 μm (bar coater # 36), and dried by heating at 50 ° C. until the solid content concentration of the coating film reached 90%. This coating film was immersed in an aqueous cleaning solution at 28 ° C. for 15 seconds, and the coating film weight before and after immersion was measured. The swelling ratio of the coating film into the aqueous cleaning solution was calculated by the following formula. The solid content concentration of the dried coating film was calculated by the same method as the content ratio of the urethane bond based on the solid content.
(Swelling ratio) = [(weight of coating film after immersion in aqueous cleaning liquid) − (weight of coating film before immersion in aqueous cleaning liquid)] / (weight of coating film before immersion in aqueous cleaning liquid) × 100
(13) The elastic modulus, tensile strength, and elongation at break of the polyurethane resin film were measured by a method based on JIS K 7311. The measurement conditions were a measurement temperature of −20 ° C., a humidity of 50%, a tensile speed of 100 mm / min, a measurement temperature of 23 ° C., a humidity of 50%, and a tensile speed of 100 mm / min.
(14) The breaking energy was determined by integrating the stress from zero elongation to elongation at break of the elongation-stress curve.
(15) The adhesion with the electrodeposited surface was evaluated as follows. An aqueous polyurethane resin dispersion was applied to an automotive steel plate cationic electrodeposition coating plate (manufactured by Nippon Test Panel Co., Ltd.) with a thickness of 40 μm (bar coater # 20), dried by heating at 140 ° C. for 30 minutes, and the resulting coating film was used. A cross-cut peel test was conducted. The coating film was cut at an interval of 1 mm vertically and horizontally in an area of 10 mm × 10 mm, and after sticking an adhesive tape, the number of cells remaining on the surface of the electrodeposition layer when peeled off was visually evaluated. For example, the case where 60 out of 100 remained was described as 60/100.

[Example 1]
[Production of aqueous polyurethane resin dispersion (1)]
In a reaction vessel into which a stirrer, a reflux condenser and a thermometer were inserted, PTMG2000 (registered trademark; poly (1,4-tetramethylene glycol) manufactured by Mitsubishi Chemical; number average molecular weight 1,962; hydroxyl value 57.2 mgKOH / g) 299 g, 2,2-dimethylolpropionic acid (DMPA) 9.80 g and N-ethylpyrrolidone (NEP) 85.5 g were charged under a nitrogen stream. 98.9 g of 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI) and 0.34 g of dibutyltin dilaurate (catalyst) were added and heated to 90 ° C. to carry out a urethanization reaction over 2.5 hours. Thereafter, 27.1 g of 12-hydroxystearic acid was injected, and stirring was continued at the same temperature for 4.5 hours to obtain a polyurethane prepolymer. The free NCO group content at the end of the urethanization reaction was 1.65% by weight. 505 g was extracted from the mixture obtained by adding and mixing 17.0 g of triethylamine to the reaction mixture, and added to 870 g of water under strong stirring. Subsequently, 17.9 g of 35 wt% diethylenetriamine aqueous solution was added to carry out chain extension reaction to obtain an aqueous polyurethane resin dispersion (1).

[Production of polyurethane film (A)]
The aqueous polyurethane resin dispersion (1) was applied as a coating material composition on a glass plate and dried at 60 ° C. for 2 hours and at 120 ° C. for 2 hours to obtain a good coating layer. The coating layer was peeled off to produce a polyurethane film (A). The film thickness of the polyurethane film (A) was 0.10 mm.

[Example 2]
[Production of aqueous polyurethane resin dispersion (2)]
In the same reaction vessel as in Example 1, PTMG2000 (registered trademark; poly (1,4-tetramethylene glycol) manufactured by Mitsubishi Chemical; number average molecular weight 1,962; hydroxyl value 57.2 mgKOH / g) 343 g, 2,2- 11.3 g of dimethylolpropionic acid (DMPA) and 98.9 g of N-ethylpyrrolidone (NEP) were charged under a nitrogen stream. 120 g of 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI) and 0.38 g of dibutyltin dilaurate (catalyst) were added and heated to 90 ° C. to carry out a urethanization reaction over 3 hours. Thereafter, 47.8 g of 12-hydroxystearic acid was injected, and stirring was continued for 3.5 hours at the same temperature to obtain a polyurethane prepolymer. The free NCO group content at the end of the urethanization reaction was 1.57% by weight. 620 g was extracted from the mixture obtained by adding and mixing 25.2 g of triethylamine to the reaction mixture, and added to 1,050 g of water under vigorous stirring. Subsequently, 20.8 g of 35% by weight diethylenetriamine aqueous solution was added to carry out chain extension reaction to obtain an aqueous polyurethane resin dispersion (2).

[Production of polyurethane film (B)]
The aqueous polyurethane resin dispersion (2) was applied as a coating material composition on a glass plate and dried at 60 ° C. for 2 hours and at 120 ° C. for 2 hours to obtain a good coating layer. The obtained coating layer was peeled off to produce a polyurethane film (B). The film thickness of the obtained polyurethane film (B) was 0.10 mm.

[Example 3]
[Production of aqueous polyurethane resin dispersion (3)]
In a reaction vessel similar to that of Example 1, PTMG2000 (registered trademark; poly (1,4-tetramethylene glycol) manufactured by Mitsubishi Chemical; number average molecular weight 1,962; hydroxyl value 57.2 mgKOH / g) 231 g, 2,2- 10.8 g of dimethylolpropionic acid (DMPA) and 113 g of N-ethylpyrrolidone (NEP) were charged under a nitrogen stream. 96.7 g of 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI) and 0.29 g of dibutyltin dilaurate (catalyst) were added and heated to 90 ° C. to carry out a urethanization reaction over 4 hours. Thereafter, 12.4 g of 12-hydroxystearic acid was injected, and stirring was continued for 2 hours at the same temperature. Further, 6.85 g of 3,5-dimethylpyrazole (DMPZ) was injected, and stirring was continued at the same temperature for 1.5 hours to obtain a polyurethane prepolymer. The free NCO group content at the end of the urethanization reaction was 1.89% by weight. 464 g was extracted from the mixture obtained by adding and mixing 12.8 g of triethylamine to the reaction mixture, and added to 660 g of water under strong stirring. Subsequently, 12.4 g of 35 wt% 2-methyl-1,5-pentanediamine aqueous solution and 11.0 g of 35 wt% diethylenetriamine aqueous solution were added to carry out chain extension reaction to obtain an aqueous polyurethane resin dispersion (3). Regarding the aqueous polyurethane resin dispersion (3), the molar ratio of the carboxy group to the blocked NCO group (terminal carboxy group / blocked NCO group) was 37/63 at the end of the polyurethane resin.

[Production of polyurethane film (C)]
The aqueous polyurethane resin dispersion (3) was applied as a coating material composition on a glass plate and dried at 60 ° C. for 2 hours and at 120 ° C. for 2 hours to obtain a good coating layer. The obtained coating layer was peeled off to produce a polyurethane film (C). The film thickness of the polyurethane film (C) was 0.10 mm.

[Example 4]
[Production of aqueous polyurethane resin dispersion (4)]
In the same reaction vessel as in Example 1, PTMG2000 (registered trademark; poly (1,4-tetramethylene glycol) manufactured by Mitsubishi Chemical; number average molecular weight 1,962; hydroxyl value 57.2 mgKOH / g) 303 g, 2,2- 9.36 g of dimethylolpropionic acid (DMPA) and 83.5 g of N-ethylpyrrolidone (NEP) were charged under a nitrogen stream. 83.7 g of isophorone diisocyanate (IPDI) and 0.33 g of dibutyltin dilaurate (catalyst) were added and heated to 90 ° C. to carry out a urethanization reaction over 3 hours. Thereafter, 26.9 g of 12-hydroxystearic acid was injected, and stirring was continued for 4 hours at the same temperature to obtain a polyurethane prepolymer. The content of free NCO groups at the end of the urethanization reaction was 1.69% by weight. 504 g was extracted from the mixture obtained by adding and mixing 16.8 g of triethylamine to the reaction mixture, and added to 860 g of water under strong stirring. Subsequently, 17.3 g of 35 wt% diethylenetriamine aqueous solution was added to carry out chain extension reaction to obtain an aqueous polyurethane resin dispersion (4).

[Production of polyurethane film (D)]
The aqueous polyurethane resin dispersion (4) was applied as a coating material composition on a glass plate and dried at 60 ° C. for 2 hours and 120 ° C. for 2 hours to obtain a good coating layer. The obtained coating layer was peeled off to produce a polyurethane film (D). The film thickness of the obtained polyurethane film (D) was 0.10 mm.

[Example 5]
[Production of aqueous polyurethane resin dispersion (5)]
In the same reaction vessel as in Example 1, PTMG2000 (registered trademark; poly (1,4-tetramethylene glycol) manufactured by Mitsubishi Chemical; number average molecular weight 1,955; hydroxyl value 57.4 mgKOH / g) 137 g, ETERNACOLL UH-200 (Registered trademark; polycarbonate diol manufactured by Ube Industries; number average molecular weight 1,975; hydroxyl value 56.8 mg KOH / g; polycarbonate diol obtained by reacting 1,6-hexanediol and dimethyl carbonate) 64.9 g, 2, 2-Dimethylolpropionic acid (DMPA) (6.61 g) and Idemitsu Kosan Ecamide M-100 (solvent) (82.6 g) were charged under a nitrogen stream. 72.3 g of 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI) and 0.25 g of dibutyltin dilaurate (catalyst) were added and heated to 90 ° C., and a urethanization reaction was performed over 2.5 hours. Thereafter, 28.0 g of 12-hydroxystearic acid was injected, and stirring was continued for 3.5 hours at the same temperature to obtain a polyurethane prepolymer. The free NCO group content at the end of the urethanization reaction was 1.48% by weight. 380 g was extracted from the mixture obtained by adding and mixing 14.8 g of triethylamine to the reaction mixture, and added to 590 g of water under strong stirring. Subsequently, 12.1 g of 35% by weight diethylenetriamine aqueous solution was added to carry out chain extension reaction to obtain an aqueous polyurethane resin dispersion (5).

[Production of polyurethane film (E)]
The aqueous polyurethane resin dispersion (5) was applied as a coating material composition on a glass plate and dried at 60 ° C. for 2 hours and at 120 ° C. for 2 hours to obtain a good coating layer. The obtained coating layer was peeled off to produce a polyurethane film (E). The film thickness of the obtained polyurethane film (E) was 0.10 mm.

[Comparative Example 1]
[Production of aqueous polyurethane resin dispersion (6)]
In the same reaction vessel as in Example 1, PTMG2000 (registered trademark; poly (1,4-tetramethylene glycol) manufactured by Mitsubishi Chemical; number average molecular weight 1,979; hydroxyl value 56.7 mgKOH / g) 300 g, 2,2- 13.7 g of dimethylolpropionic acid (DMPA) and 131 g of N-methylpyrrolidone (NMP) were charged under a nitrogen stream. 82.0 g of isophorone diisocyanate (IPDI) and 0.32 g of dibutyltin dilaurate (catalyst) were added and heated to 90 ° C., and a urethanization reaction was performed over 6 hours to obtain a polyurethane prepolymer. The content of free NCO groups at the end of the urethanization reaction was 1.63% by weight. 480 g was extracted from the mixture obtained by adding and mixing 10.3 g of triethylamine to the reaction mixture, and added to 680 g of water under strong stirring. Subsequently, 16.2 g of 35% by weight 2-methyl-1,5-pentanediamine aqueous solution was added to carry out chain extension reaction to obtain an aqueous polyurethane resin dispersion (6).

[Production of polyurethane film (F)]
The aqueous polyurethane resin dispersion (6) was applied as a coating material composition on a glass plate and dried at 60 ° C. for 2 hours and at 120 ° C. for 2 hours to obtain a good coating layer. The obtained coating layer was peeled off to produce a polyurethane film (F). The film thickness of the obtained polyurethane film (F) was 0.10 mm.

[Comparative Example 2]
[Production of aqueous polyurethane resin dispersion (7)]
In a reaction vessel similar to that of Example 1, PTMG2000 (registered trademark; poly (1,4-tetramethylene glycol) manufactured by Mitsubishi Chemical; number average molecular weight 1,979; hydroxyl value 56.7 mgKOH / g) 320 g, 2,2- 12.8 g of dimethylolpropionic acid (DMPA) and 139 g of N-methylpyrrolidone (NMP) were charged under a nitrogen stream. 96.2 g of isophorone diisocyanate (IPDI) and 0.35 g of dibutyltin dilaurate (catalyst) were added, and the mixture was heated to 90 ° C. and subjected to urethanization for 5.5 hours to obtain a polyurethane prepolymer. The free NCO group content at the end of the urethanization reaction was 2.48% by weight. 557 g was extracted from a mixture obtained by adding and mixing 10.2 g of triethylamine to the reaction mixture, and added to 820 g of water under strong stirring. Subsequently, 27.6 g of 35 wt% diethylenetriamine aqueous solution was added to carry out chain extension reaction to obtain an aqueous polyurethane resin dispersion (7).

[Production of polyurethane film (G)]
The aqueous polyurethane resin dispersion (7) was applied as a coating material composition on a glass plate and dried at 60 ° C. for 2 hours and 120 ° C. for 2 hours to obtain a good coating layer. The obtained coating layer was peeled off to produce a polyurethane film (G). The film thickness of the obtained polyurethane film (G) was 0.10 mm.

[Comparative Example 3]
[Production of aqueous polyurethane resin dispersion (8)]
In the same reaction vessel as in Example 1, ETERRNACOLL UH-200 (registered trademark; polycarbonate diol manufactured by Ube Industries; number average molecular weight 1,988; hydroxyl value 56.4 mgKOH / g; 1,6-hexanediol and dimethyl carbonate were reacted. Polycarbonate diol) 488 g, 2,2-dimethylolpropionic acid (DMPA) 15.9 g and N-methylpyrrolidone (NMP) 282 g were charged under a nitrogen stream. 176 g of 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI) and 0.55 g of dibutyltin dilaurate (catalyst) were added and heated to 90 ° C. to carry out a urethanization reaction over 3 hours. Thereafter, 66.7 g of 12-hydroxystearic acid was injected, and stirring was continued at the same temperature for 5 hours to obtain a polyurethane prepolymer. The free NCO group content at the end of the urethanization reaction was 1.34% by weight. 910 g was extracted from the mixture obtained by adding and mixing 35.5 g of triethylamine to the reaction mixture, and added to 1,190 g of water under strong stirring. Subsequently, 27.5 g of 35% by weight diethylenetriamine aqueous solution was added to carry out chain extension reaction to obtain an aqueous polyurethane resin dispersion (8).

[Manufacture of polyurethane film (H)]
The aqueous polyurethane resin dispersion (8) was applied as a coating material composition on a glass plate and dried at 60 ° C. for 2 hours and at 120 ° C. for 2 hours to obtain a good coating layer. The obtained coating layer was peeled off to produce a polyurethane film (H). The film thickness of the obtained polyurethane film (H) was 0.10 mm.

[Comparative Example 4]
[Production of aqueous polyurethane resin dispersion (9)]
In the same reaction vessel as in Example 1, ETERRNACOLL UH-200 (registered trademark; polycarbonate diol manufactured by Ube Industries; number average molecular weight 1,993; hydroxyl value 56.3 mgKOH / g; 1,6-hexanediol and dimethyl carbonate were reacted. Polycarbonate diol) 597 g, 2,2-dimethylolpropionic acid (DMPA) 18.1 g and N-methylpyrrolidone (NMP) 354 g were charged under a nitrogen stream. 180 g of isophorone diisocyanate (IPDI) and 0.64 g of dibutyltin dilaurate (catalyst) were added and heated to 90 ° C. to carry out a urethanization reaction over 3 hours. Thereafter, 80.3 g of 12-hydroxystearic acid was injected, and stirring was continued for 3 hours at the same temperature to obtain a polyurethane prepolymer. The free NCO group content at the end of the urethanization reaction was 1.38% by weight. 1,243 g was extracted from the mixture obtained by adding and mixing 41.8 g of triethylamine to the reaction mixture, and added to 1,620 g of water under vigorous stirring. Subsequently, 35.1 g of 35 wt% diethylenetriamine aqueous solution was added to carry out chain extension reaction to obtain an aqueous polyurethane resin dispersion (9).

[Production of polyurethane film (I)]
The aqueous polyurethane resin dispersion (9) was applied as a coating material composition on a glass plate and dried at 60 ° C. for 2 hours and at 120 ° C. for 2 hours to obtain a good coating layer. The obtained coating layer was peeled off to produce a polyurethane film (I). The film thickness of the obtained polyurethane film (I) was 0.10 mm.

[Comparative Example 5]
[Production of aqueous polyurethane resin dispersion (10)]
In a reaction vessel similar to that in Example 1, ETERNACOLL UH-200 (registered trademark; polycarbonate diol manufactured by Ube Industries; number average molecular weight 2,000; hydroxyl value 56.1 mgKOH / g; 1,6-hexanediol and dimethyl carbonate were added. (Polycarbonate diol obtained by reaction) 272 g, 2,2-dimethylolpropionic acid (DMPA) 18.5 g and N-methylpyrrolidone (NMP) 176 g were charged under a nitrogen stream. 125 g of 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI) and 0.33 g of dibutyltin dilaurate (catalyst) were added and heated to 90 ° C. to carry out a urethanization reaction over 5 hours. Thereafter, 10.4 g of 3,5-dimethylpyrazole (DMPZ) was injected, and stirring was continued for 1.5 hours at the same temperature to obtain a polyurethane prepolymer. The content ratio of free isocyanate groups at the end of the urethanization reaction was 1.78% by weight. 564 g was extracted from the mixture obtained by adding and mixing 13.9 g of triethylamine to the reaction mixture, and added to 870 g of water under strong stirring. Then, 36.5 g of 35% by weight 2-methyl-1,5-pentanediamine aqueous solution was added to carry out chain extension reaction to obtain an aqueous polyurethane resin dispersion (10).

[Production of polyurethane film (J)]
The aqueous polyurethane resin dispersion (10) was applied as a coating material composition on a glass plate and dried at 60 ° C. for 2 hours and 120 ° C. for 2 hours, thereby obtaining a good coating layer. The obtained coating layer was peeled off to produce a polyurethane film (J). The film thickness of the obtained polyurethane film (J) was 0.10 mm.

[Comparative Example 6]
[Production of aqueous polyurethane resin dispersion (11)]
In a reaction vessel similar to that in Example 1, PTMG2000 (registered trademark; poly (1,4-tetramethylene glycol) manufactured by Mitsubishi Chemical; number average molecular weight 1,955; hydroxyl value 57.4 mgKOH / g) 230 g, 2,2- Dimethylolpropionic acid (DMPA) 7.56 g and Idemitsu Kosan Ecamide M-100 (solvent) 109 g were charged under a nitrogen stream. 81.4 g of 4,4′-dicyclohexylmethane diisocyanate (hydrogenated MDI) and 0.28 g of dibutyltin dilaurate (catalyst) were added and heated to 90 ° C., and a urethanization reaction was performed over 2.5 hours. Thereafter, 32.2 g of 12-hydroxystearic acid was injected, and stirring was continued at the same temperature for 4 hours to obtain a polyurethane prepolymer. The free isocyanate group content at the end of the urethanization reaction was 1.55% by weight. 454 g was extracted from the mixture obtained by adding and mixing 16.8 g of triethylamine to the reaction mixture, and added to 670 g of water under strong stirring. Then, 25.3 g of a 35% by weight 2-methyl-1,5-pentanediamine aqueous solution was added to carry out a chain extension reaction to obtain an aqueous polyurethane resin dispersion (11).

[Manufacture of polyurethane film (K)]
The aqueous polyurethane resin dispersion (11) was applied as a coating material composition on a glass plate and dried at 60 ° C. for 2 hours and 120 ° C. for 2 hours to obtain a good coating layer. The obtained coating layer was peeled off to produce a polyurethane film (K). The film thickness of the obtained polyurethane film (K) was 0.10 mm.

  Urethane bond content ratio, urea bond content ratio, carbonate bond content ratio, ester bond content ratio, alicyclic structure content ratio, blocked isocyanate group content in aqueous polyurethane resin dispersions (1) to (11) The ratio (in terms of isocyanato group), acid value, terminal acid value, and weight average molecular weight are shown in Table 1. Table 2 shows the results of the water swelling rate of the coating films of the aqueous polyurethane resin dispersions (1) to (11), the swelling rate to the cleaning liquid, and the adhesion test with the electrodeposition coated surface. Table 2 shows the tensile properties of the polyurethane films (A) to (K) at -20 ° C and 23 ° C.

Abbreviations in Table 1 represent the following. H12-MDI is 4,4'-dicyclohexylmethane diisocyanate, IPDI is isophorone diisocyanate, PTMG2000 is Mitsubishi Chemical PTMG2000, UH-200 is Ube Industries' ETERNACOLL UH-200, HS is 12-hydroxystearic acid, DMPZ represents 3,5-dimethylpyrazole, MPMD represents 2-methyl-1,5-pentamethylenediamine, and DETA represents diethylenetriamine.
The notation of weight average molecular weight * indicates that measurement was impossible because it was insoluble in NMP of the eluent.

  * In Table 2 represents that measurement was impossible because the coating film was cracked at -20 ° C. ** indicates that measurement was impossible because the coating film was dissolved.

  The aqueous polyurethane resin dispersions of Examples 1 to 5 have a high swelling ratio of the coating film to the cleaning liquid, a low water swelling ratio, a low elastic modulus at −20 ° C., a high breaking energy, and an electrodeposited coating surface. High adhesion. As described in Comparative Example 1, when the hydroxyalkanoic acid and the polyamine having three or more amino groups and / or imino groups are not contained in the molecule, the swelling ratio to the cleaning liquid is lowered, and the electrodeposited surface Adhesion with is reduced. As described in Comparative Example 2, when the hydroxyalkanoic acid is not contained, the water swelling rate is increased, the coating film is cracked at a low temperature, and the adhesion with the electrodeposited surface is lowered. As described in Comparative Example 3 and Comparative Example 4, when the polyether polyol is not contained, the elastic modulus increases, the breaking energy decreases, and the adhesion with the electrodeposited surface decreases. As described in Comparative Example 5, the means for improving the cleaning properties described in the prior art does not provide sufficient cleaning properties, the elastic modulus at −20 ° C. is high, and the elongation at break is low. As described in Comparative Example 6, when the hydroxyalkanoic acid is contained and the polyamine having three or more amino groups and / or imino groups is not contained in the molecule, the water swelling rate is increased and the tensile strength is increased. Lower.

  The aqueous polyurethane resin dispersion can be widely used as a raw material for paints and coating materials. The aqueous polyurethane resin dispersion of the present invention is particularly useful as a raw material for paints and coating agents for providing a protective coating for an electrodeposition coating on steel sheets for building materials, electrical equipment, vehicles, industrial equipment, office machines, etc. .

Claims (8)

(A) polyisocyanate compound, (b) a polyol compound, (c) an acidic group-containing polyol compound, and (d) glycolic acid (2-hydroxyacetic acid), 3-hydroxybutyric acid, 4-hydroxybutyric acid, 10-hydroxy decanoic acid Hydroxypivalic acid (2,2-dimethyl-3-hydroxypropionic acid), 12-hydroxydodecanoic acid, 16-hydroxyhexadecanoic acid, lactic acid, 3-hydroxypropionic acid, 2-hydroxyoctanoic acid, 3-hydroxyundecanoic acid And (A) a polyurethane prepolymer obtained by reacting a hydroxyalkanoic acid selected from the group consisting of 12-hydroxystearic acid and 12-hydroxyoleic acid , and isocyanato group reactive with the polyurethane prepolymer (B ) Obtained by reacting with chain extender Polyurethane resin is an aqueous polyurethane resin dispersion which is dispersed in an aqueous medium,
(B) The polyol compound includes a polyether polyol having a number average molecular weight of 800 to 3,500,
(B) The chain extender includes a polyamine compound having a total of 3 or more amino groups and / or imino groups in one molecule,
The polyurethane resin has a total content of urethane bonds and urea bonds of 6 to 20% by weight based on solid content, and a content ratio of ester bonds and / or carbonate bonds of less than 10% by weight based on solid content. An aqueous polyurethane resin dispersion having a weight average molecular weight of 50,000 or more. (A) polyisocyanate compound, (b) polyol compound, (c) acidic group-containing polyol compound, (d) glycolic acid (2-hydroxyacetic acid), 3-hydroxybutyric acid, 4-hydroxybutyric acid, 10-hydroxydecanoic acid, Hydroxypivalic acid (2,2-dimethyl-3-hydroxypropionic acid), 12-hydroxydodecanoic acid, 16-hydroxyhexadecanoic acid, lactic acid, 3-hydroxypropionic acid, 2-hydroxyoctanoic acid, 3-hydroxyundecanoic acid, (A) polyurethane prepolymer obtained by reacting a hydroxyalkanoic acid selected from the group consisting of 12-hydroxystearic acid and 12-hydroxyoleic acid, and (e) a blocking agent of an isocyanato group dissociating at 80 to 180 ° C. A polymer and the polyurethane prepolymer Reactive to Soshianato group (B) a chain extender and a polyurethane resin obtained by reacting a is an aqueous polyurethane resin dispersion which is dispersed in an aqueous medium,
(B) The polyol compound includes a polyether polyol having a number average molecular weight of 800 to 3,500,
(B) The chain extender includes a polyamine compound having a total of 3 or more amino groups and / or imino groups in one molecule,
The polyurethane resin has a total content of urethane bonds and urea bonds of 6 to 20% by weight based on solid content, and a content ratio of ester bonds and / or carbonate bonds of less than 10% by weight based on solid content. An aqueous polyurethane resin dispersion having a weight average molecular weight of 50,000 or more. The aqueous polyurethane resin dispersion according to claim 1 or 2 , wherein the acid value of the polyurethane resin is 10 to 40 mgKOH / g, and the acid value derived from the molecular terminal of the polyurethane resin is 3 to 30 mgKOH / g. The aqueous polyurethane resin dispersion according to any one of claims 1 to 3 , wherein (a) the polyisocyanate compound is an alicyclic diisocyanate.   The water-based polyurethane resin dispersion as described in any one of Claims 1-4 whose alicyclic structure content rate in a polyurethane resin is 6-30 weight% on solid content basis. The aqueous polyurethane resin dispersion according to any one of claims 2 to 5, wherein the blocking agent (e) is at least one selected from the group consisting of an oxime compound, a pyrazole compound, and a malonic ester compound. body.   The coating material composition containing the water-based polyurethane resin dispersion as described in any one of Claims 1-6.   The polyurethane resin film manufactured by heat-drying the composition containing the water-based polyurethane resin dispersion as described in any one of Claims 1-6.