WO2009119065A1 - Aqueous polyurethane dispersing element and manufacturing method thereof - Google Patents

Abstract

The objective is to provide an aqueous polyurethane dispersing element with excellent dispersion properties as well as excellent producibility (concretely, where control of the reaction is easy and the polyurethane dispersing element obtained also has consistent quality and can be supplied to the market) and wherein diphenylmethane diisocyanate is used as the organic diisocyanate, and a method for manufacturing said dispersing element. The problem above is solved by using diphenylmethane diisocyanate configured from three kinds of isomers, namely, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and 2,2'-diphenylmethane diisocyanate, which comprises 2,4'-diphenylmethane diisocyanate above a specified proportion.

Description

Aqueous polyurethane dispersion and method for producing the same

The present invention relates to an aqueous polyurethane dispersion using diphenylmethane diisocyanate (hereinafter abbreviated as “MDI”) as an organic diisocyanate, and a method for producing the dispersion.

Paints, adhesives and coating agents containing organic solvents have adverse effects on human bodies, safety and health problems such as explosion and fire, and pollution problems such as air pollution and water pollution. In order to improve these problems, the development of water system has been actively conducted in recent years. *

Various resins such as an acrylic resin, a polyurethane resin, a polyester resin, and a latex are used as the resin for the aqueous system. Among them, polyurethane resin is excellent in durability, abrasion resistance, and the like, and therefore, attempts to apply it to an aqueous system in various usages are widely made. For example, Patent Document 1 discloses a water-dispersible polyurethane-based paint, and Patent Document 2 discloses a water-dispersible polyurethane-based adhesive. These are water-based polyurethane resins alone, but in order to combine the characteristics of each resin, a combination of various resins such as an acrylic emulsion and a polyurethane emulsion has been studied. *

However, the water-based polyurethane resins described in Patent Document 1 and Patent Document 2 basically do not satisfy all required performances such as adhesiveness, adhesion, and alkali resistance, and the appearance of such resins has been desired. . *

As an improvement, Patent Document 3 discloses a water-dispersed urethane-urea using a specific aromatic diisocyanate and an aliphatic diisocyanate that is price competitive and has excellent heat resistance, chemical resistance, mechanical strength, and the like. It is shown. However, the aromatic diisocyanate in Patent Document 3 has a reactivity that is too high, so that the amount of introduction in the production method and the polyurethane resin is limited. *

In addition, for the purpose of obtaining higher mechanical strength of the resulting resin, a method of introducing only MDI as an aromatic diisocyanate has been studied (see, for example, Patent Document 4 and Patent Document 5). However, when MDI is used as the aromatic diisocyanate, the reactivity is too high as described above, and therefore an extremely excellent production (stirring) facility needs to be sophisticated. Moreover, even if the production (stirring) equipment is sophisticated, it is extremely difficult to produce a dispersion because of the high reactivity. *

Japanese Patent Laid-Open No. 4-198361 Japanese Patent Laid-Open No. 5-117358 JP 2005-29793 A JP 62-109813 A JP-A-1-168756

In view of the background as described above, the present invention can stably disperse even when MDI is used as an organic diisocyanate, even if the production (stirring) equipment is not extremely sophisticated, and even when using ordinary synthesis equipment. It is an object of the present invention to obtain an aqueous polyurethane dispersion excellent in water resistance. *

Further, the present invention provides an aqueous polyurethane dispersion excellent in productivity (specifically, reaction control is easy, and the resulting polyurethane dispersion can be supplied to the market with stable quality). An object is to provide a manufacturing method.

MDI is 4,4′-diphenylmethane diisocyanate (hereinafter abbreviated as “4,4′-MDI”), 2,4′-diphenylmethane diisocyanate (hereinafter abbreviated as “2,2′-MDI”), It consists of three isomers of 2'-diphenylmethane diisocyanate (hereinafter abbreviated as "2,2'-MDI"). As a result of intensive studies to solve the above-described series of problems, the present inventors have used MDI containing 2,4′-MDI in a ratio higher than a specific ratio as an organic diisocyanate. As a result, the present invention has been completed. *

That is, the present invention is shown in the following (1) to (2). *

(1) A polyurethane resin obtained by reacting an organic diisocyanate (A), a polymer polyol (B), a carboxyl group-containing low molecular glycol (C), a neutralizer (D), and a chain extender (E) in water. An aqueous polyurethane dispersion obtained by emulsifying, wherein the organic diisocyanate (A) is diphenylmethane diisocyanate (A1) containing 75% by mass or more of 2,4′-diphenylmethane diisocyanate. *

(2) Neutralizing isocyanate group-terminated prepolymer obtained by reacting organic diisocyanate (A), polymer polyol (B), and low molecular glycol (C) containing a carboxyl group with neutralizing agent (D) Then, after being dispersed in water, a chain extension reaction is performed with a chain extender (E), and the method for producing an aqueous polyurethane dispersion according to (1).

According to the present invention, when MDI is used as an organic diisocyanate, an aqueous polyurethane dispersion excellent in dispersibility can be obtained even if the production (stirring) equipment is not extremely sophisticated. *

Further, according to the present invention, even when MDI is used as an organic diisocyanate, productivity (specifically, reaction control is easy, and the polyurethane dispersion obtained can be supplied to the market with stable quality. It is also possible to provide a method for producing an aqueous polyurethane dispersion excellent in

The present invention will be described in further detail. *

The aqueous polyurethane dispersion of the present invention is obtained by reacting an organic diisocyanate (A), a polymer polyol (B), a carboxyl group-containing low molecular glycol (C), a neutralizer (D), and a chain extender (E). In the aqueous polyurethane dispersion obtained by emulsifying the obtained polyurethane resin in water, MDI (A1) containing 75% by mass or more of 2,4′-MDI is used as the organic diisocyanate (A). *

<Organic Diisocyanate (A)> As described above, MDI is composed of three isomers of 4,4′-MDI, 2,4′-MDI, and 2,2′-MDI. The isomer composition ratios of these MDIs in the present invention can ensure excellent dispersibility in the obtained aqueous polyurethane dispersion, and also can improve productivity (specifically, reaction control is easy and the resulting polyurethane dispersion can be obtained). In view of the fact that the MDI is 100 mass%, the content of 2,4′-MDI is 75 mass% or more (preferably 80 mass%). It is necessary to be 95.0% by mass or more, particularly preferably from the viewpoint that the more stable dispersibility of the aqueous polyurethane dispersion and productivity can be reliably obtained. The isomer composition ratio of MDI can be obtained from a calibration curve based on the area percentage of each peak obtained by GPC or gas chromatography (hereinafter abbreviated as “GC”). *

In the present invention, on the premise that the performance desired in the present invention is satisfied, the organic diisocyanate component (A1) and the 2,4′-MDI are 75% by mass or more as the organic isocyanate component, if necessary. Isocyanate group-containing components other than the contained MDI (A1) can be used in combination. Examples of the isocyanate component that can be used in combination include MDI containing less than 75% by mass of 2,4′-MDI, an MDI-based condensate (a so-called dinuclear MDI having two benzene rings and two isocyanate groups, An organic polyisocyanate containing both MDI-based polynuclear condensates each having three or more benzene rings and isocyanate groups called so-called polynuclear bodies (in this case, the total of MDI and MDI-based multinuclear condensates is 100% by mass); Aromatics such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylene-1,4-diisocyanate, xylene-1,3-diisocyanate, tetramethylxylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate Diisocyanate, tetramethylene diiso Alicyclic diisocyanates such as aliphatic diisocyanates such as anate, hexamethylene diisocyanate, 3-methyl-1,5-pentane diisocyanate, lysine diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate, etc. Is mentioned. Further, urethanized products, urea compounds, allophanates, biurets, carbodiimidides, uretoniminates, uretdiones, isocyanurates, and the like obtained by reacting with these polymeric substances and active hydrogen group-containing compounds are also included. Furthermore, the mixture which consists of 2 or more types of these series of isocyanate group containing compounds is also mentioned. *

<Polymer polyol (B)> As the polymer polyol used in the present invention, polyester polyol, polyether polyol, polycarbonate polyol or the like is used, and those used as a raw material for polyurethane resin are used. No special provisions are made. *

The polymer polyol used in the present invention has a number average molecular weight of 800 to 6,000 (more preferably a number average molecular weight of 800 to 2,500, and particularly preferably a more stable dispersibility of an aqueous polyurethane dispersion, In addition, those having a number average molecular weight of 1,000 to 2,000 are preferable from the viewpoint that productivity can be reliably obtained. Typically, polypropylene ethylene polyol (PPG), polytetramethylene ether glycol (PTG) And the like. *

More specifically, polyester polyols include phthalic acid, isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, succinic acid, malonic acid, adipic acid, 1,4-cyclohexyl dicarboxylic acid, maleic acid, fumaric acid, and other two types. Basic acids and the like, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 3,3-dimethylol heptane, diethylene glycol, dipropylene glycol, neopentyl glycol, cyclohexane-1,4-diol, or glycerin, trimethylolpropane, pentaerythritol, etc. From the polyols Polyester polyols obtained by the polycondensation reaction are employed. Furthermore, cyclic esters such as ε-caprolactone, polyester amide polyols in which a part of the diol is changed to amines such as hexamethylene diamine and isophorone diamine can be used. *

Polyether polyols include the above diols, polyols, or these and amines such as ethylenediamine, propylenediamine, toluenediamine, metaphenylenediamine, diphenylmethanediamine, alkylene oxides such as ethylene oxide and propylene oxide, and methylglycidyl. A polyether polyol obtained by addition polymerization of an ether, an alkyl such as phenyl glycidyl ether or an aryl glycidyl ether, a cyclic ether such as tetrahydrofuran is used. *

As the polycarbonate polyol, a polycarbonate polyol obtained by a reaction of the diols or polyols with ethylene carbonate, diethyl carbonate, diphenyl carbonate or the like is used. *

<Carboxyl group-containing low molecular glycol (C)> As the carboxyl group-containing low molecular glycol (C) used in the present invention, a fatty acid having two terminal hydroxyl groups is preferably used. This fatty acid has two terminal hydroxyl groups as active hydrogen groups. For example, the active hydrogen groups at both ends react with isocyanate groups and are incorporated into the main chain of the prepolymer, and the free carboxyl groups are hydrophilic, so It works to increase dispersibility. Examples of the fatty acid compound having an active hydrogen group include dimethylolpropionic acid and dimethylolbutanoic acid having two terminal hydroxyl groups.

<Neutralizing agent (D)> The neutralizing agent (D) used in the present invention neutralizes the carboxyl group of the carboxyl group-containing low molecular glycol incorporated in the urethane prepolymer main chain, thereby dispersing the polyurethane resin in water. Gives the effect of improving the nature. Examples of the neutralizing agent (D) include tertiary amines (such as triethylamine). *

<Chain extender (E)> As the chain extender (D) used in the present invention, a compound having 3 or more active hydrogens is used. Examples of the compound having 3 or more active hydrogens include ethylenediamine (EDA), ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, diethanolamine, diethylenetriamine (DETA), and triethylene. Examples include tetramine, tetraethylenepentamine, and pentaethylenehexamine. *

<Optional Component> The aqueous polyurethane dispersion in the present invention includes the specific organic diisocyanate (A), the polymer polyol (B), the carboxyl group-containing low molecular glycol (C), the neutralizer (D), and the chain extension. Agent (E) is essential, but if necessary, a viscosity reducing agent that has an effect of promoting dispersion in water (solubility in water of 0.1 to 40% by mass and flash point of 50 ° C or higher) is added. can do. Specific examples of the viscosity reducing agent include dipropylene glycol dimethyl ether (trade name: dimethylpropylene diglycol (abbreviation: DMFDG, solubility in water: 37.0 mass%, flash point: 65 ° C.), diethylene glycol dibutyl ether (commercial product). Name: Dibutyldiglycol, Abbreviation: DBDG, Solubility in water: 0.3 mass%, Flash point: 122 ° C., N-methylpyrrolidone (abbreviation: NMP, Solubility in water: (optional) mass%, Flash point) : 91 ° C.) and the like.

Further, in the aqueous polyurethane dispersion in the present invention, a metal catalyst such as dibutyltin dilaurate or zinc naphthenate, or triethylenediamine, if necessary, for the purpose of accelerating the reaction in forming a polyurethane resin. An amine catalyst such as N-methylmorpholine and the like, and a resinification catalyst (urethanization catalyst) as a urethane reaction curing catalyst (polymerization catalyst) can be used together. *

Furthermore, for the purpose of enhancing the desired physical properties of the aqueous polyurethane dispersion of the present invention and adding various physical properties, various additives include flame retardants, plasticizers, antioxidants, ultraviolet absorbers, fillers, Internal release agents, reinforcing materials, matting agents, conductivity imparting agents, charge control agents, antistatic agents, lubricants, and other processing aids can be used. *

<Method for Producing Aqueous Polyurethane Dispersion> Next, a method for producing the aqueous polyurethane dispersion of the present invention will be described. The series of specific organic diisocyanate (A), polymer polyol (B), and carboxyl group-containing low molecular glycol (C) are reacted. Under the present circumstances, you may interpose the viscosity reducing agent which has the effect which promotes the dispersion | distribution to the water mentioned as said arbitrary component, and a urethanization catalyst in a reaction system. Next, the carboxyl group is neutralized with the tertiary amine (D) to obtain an isocyanate group-terminated prepolymer having a carboxylic acid amine salt and having improved water dispersibility. After this isocyanate group-terminated prepolymer is dispersed in water and emulsified, the aqueous polyurethane dispersion of the present invention is obtained by performing a chain extension reaction with the chain extender (E). *

In this case, the step of emulsifying by dispersing the isocyanate group-terminated prepolymer in water is a system in which water is pre-charged rather than adding and dispersing water in the system in which the isocyanate group-terminated prepolymer is preliminarily charged. It is preferable to add and disperse an isocyanate group-terminated prepolymer therein to emulsify.

EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is limited to these and is not interpreted. In the examples and comparative examples, “parts” and “%” indicate “parts by mass” and “mass%”, respectively, unless otherwise specified. *

<Example 1> A reactor having a capacity of 1,000 ml equipped with a stirrer, a thermometer, a nitrogen seal tube, and a cooler, 208.4 g of polyol A, 11.2 g of dimethylolpropionic acid (DMPA), and As an optional component for reducing the viscosity, 50.0 g of dipropylene glycol dimethyl ether (DMFDG) was charged, and the mixture was stirred at 90 ° C. and uniformly mixed. Next, after cooling to 60 ° C., 75.0 g of 2,4′-MDI was charged and reacted at 80 ° C. for 2 hours with stirring. Next, 50.0 g of N-methylpyrrolidone (NMP) was charged as an optional component for lowering the viscosity, and further stirred for 1 hour. After stirring, after confirming that the isocyanate group content before neutralization is 2.4% by mass, 8.4 g of triethylamine (TEA) was added to neutralize the carboxyl group, and the polyurethane having an isocyanate group at the terminal A prepolymer was obtained. Next, using a stirrer (Homomixer manufactured by Tokushu Kika Kogyo Co., Ltd.), 561.0 g of water was charged while stirring and the phases were changed. Immediately after phase inversion, amine water (15% aqueous solution) consisting of 30.6 g of water and 5.4 g of ethylenediamine (EDA) was charged in advance to carry out emulsification and chain extension reaction between water and amine. The reaction was terminated when the presence of isocyanate groups was no longer confirmed by FT-IR, and an aqueous polyurethane dispersion (resin emulsion) was obtained. The dispersion had a solid content of 29.8%, a pH of 8.8, a viscosity at 25 ° C. of 21 mPa · s, an average particle size (measuring device: manufactured by Otsuka Electronics Co., Ltd .: electrophoretic light scattering system “ELS-800”) ) Was 133 nm. *

<Examples 2 to 7, Comparative Examples 1 to 4> According to the composition (blending ratio) shown in Table 1, each aqueous polyurethane dispersion (resin emulsion) was obtained by the same apparatus and method as in Example 1. In Comparative Example 3 and Comparative Example 4, when water was started to be charged, foaming caused by excessive reactivity between the isocyanate group and water occurred. Canceled. *

The details of the composition (each component) in Table 1 are as follows. *

<2,4′-MDI (corresponding to the organic diisocyanate (A1) of the present invention)> (i) MPC peak area ratio by GPC = 100% (ii) 4,4′-MDI ratio in MDI = 1% (Measurement by GC) (iii) Ratio of 2,4′-MDI in MDI = 98% (measurement by GC) (iv) Ratio of 2,2′-MDI in MDI = 1% (measurement by GC) ( v) Isocyanate group content = 33.6% <4,4'-MDI> (i) MDI peak area ratio by GPC = 100% (ii) 4,4'-MDI ratio in MDI = 98% ( (Iii) (iii) 2,4'-MDI ratio in MDI = 1% (measured by GC) (iv) 2,2'-MDI ratio in MDI = 1% (measured by GC) ) (V) Isocyanate group content = 33.6% <Polyol A (corresponding to the polymer polyol (B) of the present invention)> Polycarbonate diol obtained by reacting diethyl carbonate and 1,6-hexanediol Number average molecular weight = 2,000 Nominal functional group number = 2 Nominal hydroxyl value = 56.1 (mgKOH / g) <Polyol B (corresponding to the polymer polyol (B) of the present invention)> Polytetramethylene ether glycol Number average molecular weight = 2,000 Nominal functional group number = 2 Nominal hydroxyl value = 56.1 (mgKOH / g) Trade name "PTG-2000SN" (manufactured by Hodogaya Chemical Co., Ltd.) <DMPA (carboxyl group-containing low molecular weight glycol (C) of the present invention) Equivalent)> Dimethylolpropionic acid Trade name “DMPA” (G O Specialty Chemicals Co., Ltd.) <DMFDG (optional component)> Dimethylpropylene diglycol (abbreviation: DMFDG) Solubility in water: 37.0% by mass Flash point: 65 ° C. Trade name “dimethylpropylene diglycol” (Nippon Emulsifier Co., Ltd.) )) <NMP (arbitrary component)> N-methyl-2-pyrrolidone Solubility in water: (arbitrary) Mass% Flash point: 91 ° C. Product name “N-methyl-2-pyrrolidone” (Mitsubishi Chemical Corporation) ) <TEA (corresponding to the neutralizing agent (D) of the present invention)> Triethylamine Trade name “Triethylamine” (manufactured by Kishida Chemical Co., Ltd.) <EDA (corresponding to the chain extender (E) of the present invention)> Ethylenediamine "Ethylenediamine" (manufactured by Tosoh Corporation) <Water> Purified water

<Evaluation of Dispersion State in Aqueous Polyurethane Dispersion> About 200 g of each of the aqueous polyurethane dispersions obtained in each of the examples and comparative examples (excluding a part) was charged in a glass sample bottle, and 24 hours in a 25 ° C. atmosphere. Left to stand. After standing, the dispersion state was visually confirmed and evaluated. “◯”: A uniform dispersion state is maintained. “Δ”: Some signs of liquid phase separation are observed. “X”: Phase separation of the liquid occurs. *

As shown in Table 1, when an MDI having a 2,4′-MDI ratio of 75% by mass or more was used, a good aqueous polyurethane dispersion was obtained. In particular, as the proportion of 2,4′-MDI was increased, a very good aqueous polyurethane dispersion having a low viscosity and a fine resin average particle diameter was obtained. *

On the other hand, when the ratio of 2,4′-MDI in MDI was less than 75% by mass, there was a problem that the dispersion state of the liquid was not stable (phase separation or its sign occurred). Further, when the ratio of 2,4′-MDI in MDI was 49% by mass or less, it was impossible to obtain an aqueous dispersion as described above. *

<Examples 8 and 9> According to the composition (blending ratio) shown in Table 2, the same apparatus and method as in Examples 1 to 7 and Comparative Examples 1 to 4 described above, an aqueous polyurethane dispersion (resin emulsion) “PE— 8 "and" PE-9 "were obtained. The dispersion state in the aqueous polyurethane dispersion was evaluated by the same method as in Examples 1 to 7 and Comparative Examples 1 to 4. *

The details of the composition (each component) in Table 2 are as follows (the same components as in Table 1 are used for those not described). *

<Polyol C (corresponding to the polymer polyol (B) of the present invention)> Polycarbonate diol obtained by reacting diethyl carbonate and 1,6-hexanediol Number average molecular weight = 1,000 Nominal functional group = 2 Nominal hydroxyl value = 112.2 (mgKOH / g)

<Evaluation of film properties using aqueous polyurethane dispersion> <Reference Examples 1 and 2> For the above aqueous polyurethane dispersions “PE-8” and “PE-9”, the aqueous polyurethane dispersion was cast on a plate glass. The film was dried at 25 ° C. for 5 days to prepare a dry film having a predetermined film thickness, and the physical properties described below were measured. A series of results are shown in Table 3. <Tensile properties> Tensile test (25 ° C .: 100% modulus, strength at break, elongation): Tensile speed = 200 mm / min A sample was prepared by punching with a No. 4 dumbbell of JIS K6301 (1995). Tensile property measuring apparatus: Tensilon UTA-500 <Tearing property> Tear test (25 ° C .: Tear strength) manufactured by Orientec Co., Ltd .: Measured according to JIS K7312. *

As shown in Table 3, when the physical properties of a film obtained using MDI (A1) having a 2,4′-MDI ratio of 75% by mass or more were evaluated, it was a resin (film) having good performance. And the result was obtained.

The aqueous polyurethane dispersion obtained by the present invention can be suitably used for various water-based polyurethane resin applications such as aqueous paints and aqueous adhesives.

Claims (2)

A polyurethane resin obtained by reacting an organic diisocyanate (A), a polymer polyol (B), a carboxyl group-containing low molecular glycol (C), a neutralizing agent (D), and a chain extender (E) is emulsified in water. The aqueous polyurethane dispersion according to claim 1, wherein the organic diisocyanate (A) is diphenylmethane diisocyanate (A1) containing 75% by mass or more of 2,4′-diphenylmethane diisocyanate. After neutralizing an isocyanate group-terminated prepolymer obtained by reacting an organic diisocyanate (A), a high-molecular polyol (B), and a low-molecular glycol (C) containing a carboxyl group with a neutralizing agent (D). The method for producing an aqueous polyurethane dispersion according to claim 1, wherein a chain extension reaction is performed with a chain extender (E) after being dispersed in water.