JPS6135212B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an aqueous polyurethane resin dispersion, and more particularly, to a method for producing an aqueous polyurethane resin dispersion obtained by using a novel dispersant. More specifically, high molecular weight polyurethane obtained by using a hydrophilic urethane prepolymer containing ethylene oxide units in the molecular chain and having isocyanate groups at the ends as a dispersant and a chain extender. The present invention relates to a method for producing an aqueous resin dispersion. Conventionally, the method for producing an aqueous polyurethane dispersion is as follows: (1) Hydrophilic groups, such as carboxyl groups, sulfonic acid groups, amino groups, etc., are introduced into urethane resin, polymerized in an organic solvent solution, and then emulsified and dispersed in water. Self-emulsification method. (2) A method in which a hydrophobic high molecular weight urethane resin is synthesized in an organic solvent solution and then emulsified and dispersed in water in the presence of an emulsifier. However, when producing an aqueous urethane resin dispersion using these methods, a large amount of mechanical shear is required during forced dispersion, resulting in a lack of emulsion stability and the need to recover organic solvents during or after emulsification. It was disadvantageous from a pharmaceutical standpoint. Additionally, method (2) requires a large amount of emulsifier, lacks emulsion stability, and produces
The strength of the dried film was decreased, water resistance was poor, and physical properties were poor. Furthermore, (3) a method in which a urethane prepolymer having isocyanate groups at the ends and an aqueous surfactant solution are mixed and vigorously stirred to emulsify and disperse, and if necessary, the chain is extended with diamine or the like. (4) In the urethane prepolymer having isocyanate groups at the ends, hydrophilic groups such as carboxyl groups,
A method of introducing sulfonic acid groups, amino groups, etc. to impart self-emulsifying properties, emulsifying and dispersing in water, and extending the chain with an amino compound if necessary. Among these methods, (3)
These methods require a large amount of surfactant, and the resulting dried film has poor physical properties, particularly water resistance. In addition, (4) requires a large amount of mechanical shear during dispersion, making it difficult to produce industrially. Polyurethane with a high molecular weight has the disadvantage that the stability of the dispersion is poor. Furthermore, if a stable dispersion is prepared by lowering the molecular weight, the resulting dry film will have poor mechanical properties and will be of little practical use. Furthermore, since a certain amount or more of hydrophilic groups are introduced into the polyurethane resin, the dry film obtained from the dispersion tends to absorb water and swell, and furthermore, there is a disadvantage that the mechanical properties deteriorate significantly in the wet state. have. In addition, in the self-emulsification method, since the molecular chain contains quaternized amino groups, carboxylic acid groups, and sulfonic acid groups, the weather resistance and hydrolysis resistance of the polyurethane resin are greatly reduced, and the various performances of the polyurethane itself are affected. be lost. In general, methods using surfactants destroy the dispersion liquid during use and have a negative effect on the physical properties of the dried film, especially water resistance and solvent resistance, and its use is extremely limited, while methods that introduce hydrophilic groups are , the resulting dry coating tends to absorb water and swell, and is defective if it has reduced mechanical properties in the wet state. As a result of intensive research in order to obtain a polyurethane resin aqueous dispersion free from the above-mentioned drawbacks, the inventors of the present invention have obtained a polyurethane resin aqueous dispersion by emulsifying and dispersing a hydrophobic dispersed urethane prepolymer with a hydrophilic urethane polymer dispersant. This is what we discovered. Furthermore, the high molecular weight polyurethane resin aqueous dispersion obtained by the method of the present invention eliminates the above-mentioned drawbacks, has excellent mechanical and chemical stability, and has excellent mechanical properties, water resistance, solvent resistance, and light resistance. It is capable of exhibiting various performances such as gender. That is, in the present invention, when producing a urethane resin aqueous dispersion consisting of an isocyanate-terminated hydrophobic urethane prepolymer, a dispersant, and a water chain extender, 40 ethylene oxide units are added to the molecular chain as a dispersant.
This is a method for producing an aqueous urethane resin dispersion, characterized by using a hydrophilic urethane prepolymer containing ~98% by weight and having isocyanate groups at the ends. Furthermore, the present invention relates to a method for producing a high molecular weight polyurethane resin aqueous dispersion in which a hydrophobic urethane prepolymer is dispersed in water using a hydrophilic urethane prepolymer as a dispersant, and then the molecular weight is increased with a chain extender. The characteristics of the high molecular weight polyurethane resin aqueous dispersion obtained by the present invention are that the hydrophilic urethane prepolymer used as a dispersant is ultimately made to have a high molecular weight together with the hydrophobic urethane prepolymer,
It does not remain as a low molecular weight dispersant and does not exhibit any of the drawbacks of conventional surfactants. Furthermore, compared to self-emulsifying polyurethane resins, when compared to self-emulsifying polyurethane resins, a stable dispersion can be obtained with a much smaller hydrophilic portion, which is also a drawback of self-emulsifying resins. There is very little deterioration in mechanical properties in a water-wet state, making it possible to use it in a wide range of applications. The dispersant used in the present invention and characterized by the present invention has 40 to 40 ethylene oxide units in its molecular chain.
It is a urethane compound containing 98% by weight and having an isocyanate group at the end, and is basically a polyalkylene ether polyol containing 40% by weight or more of ethylene oxide units, or together with polyester polyol or even a low molecular weight polyalkylene ether polyol. An isocyanate-terminated urethane prepolymer obtained by stoichiometrically reacting polyisocyanate with an excess of isocyanate groups in a mixture with glycols.Theoretically, each prepolymer molecule contains 40 to 98% by weight of ethylene oxide units. It is important that
It is essential. The dispersant referred to here is a mixture of an isocyanate-ended prepolymer having an ethylene oxide unit content of 40% by weight or less and an isocyanate-terminated prepolymer having an ethylene oxide unit content of 40% by weight or more. It won't happen. Furthermore, the content of ethylene oxide units in one molecular chain of the prepolymer is preferably 60 to 90%. Here, if the content of ethylene oxide units in one molecule of the isocyanate-terminated prepolymer that acts as a dispersant is 40% by weight or less, it is necessary to use a large amount as a dispersant for the hydrophobic prepolymer, and self-emulsifying urethane Has a similar structure to resin,
Mechanical properties deteriorate significantly when wet with water. Furthermore, if the content of ethylene oxide units in one molecule of the prepolymer exceeds 98% by weight, the function as a dispersant will deteriorate, making it impossible to obtain a stable dispersion. Although such compounds themselves and their production methods are widely known, the feature of the present invention is that such compounds have a chemical structure configured to have the ability to disperse hydrophobic urethane prepolymers. and the use of such a compound as a dispersing agent.Furthermore, by polymerizing the hydrophobic urethane prepolymer with a chain extender after dispersing it, a stable high molecular weight polyurethane resin aqueous dispersion with excellent performance can be obtained. This is what I found. Polyalkylene ether polyols containing 40% by weight or more of ethylene oxide units used in the production of the reactive hydrophilic prepolymer that is the dispersant of the present invention include ethylene glycol, diethylene glycol, glycerin, trimethylolpropane, and trimethylolethane. Addition reaction of ethylene oxide or ethylene oxide with other alkylene oxides (e.g. propylene oxide, butylene oxide, styrene oxide, etc.) using a compound having active hydrogen such as pentaerythritol, sorbitol, seuucrose, ethylenediamine, ethanolamine, etc. as an initiator; It is a compound obtained by co-addition reaction, or a mixture of two or more thereof. Furthermore, mixtures of these and polyester polyols, polypropylene ether glycols, and polybutylene ether glycols, which are commonly used in the synthesis of polyurethane resins described below, are also included. The polyol compound having hydroxyl groups at the ends that can be used here has a molecular weight of about 1.000 to 13.000, and preferably has a hydroxyl value in the range of about 10 to 130. For example, if the hydroxyl value is less than 10, the amount of polyisocyanate compound to be added will be small, and ultimately the number of isocyanate groups will be too small, making it difficult to achieve the object of the present invention. On the other hand, if the hydroxyl value exceeds 130, the amount of polyisocyanate compound added becomes large and sufficient dispersibility cannot be obtained. On the other hand, polyisocyanate compounds reacted with polyol compounds having hydroxyl groups at their ends include, for example, 2.4- and 2.6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1.5-naphthylene diisocyanate, xylylene diisocyanate, Dicyclohexylmethane-4,4'-diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, 1,6-hexamethylene diisocyanate, 2,6-diisocyanate methyl caproate, singly or in mixtures thereof, and Examples include dimers and trimers of . The above polyhydroxy compounds and polyisocyanate compounds contain excess isocyanate groups.
A hydrophilic urethane compound having isocyanate groups at the ends is obtained by reacting at a ratio of NCO/OH = 1.3 to 2.0 at a temperature of 50 to 150°C. Furthermore, if necessary, it is also possible to use hydrophobic organic solvents such as toluene, xylene, trichloroethylene, trichloroethane, ethylene dichloride, and the like. Theoretically, it is important that the hydrophilic urethane prepolymer having isocyanate groups at the ends of the hydrophilic urethane prepolymer obtained in this manner contains 40 to 98% by weight of ethylene oxide units in the chain per molecule of the prepolymer. , preferably ethylene oxide units
It is 50-90% by weight. Furthermore, the molecular weight of the hydrophilic urethane prepolymer is about 1,300 to 30,000. If the molecular weight is 30,000 or more, the viscosity of the aqueous polyurethane resin dispersion becomes abnormally high, making it impossible to obtain a high solid content dispersion of high molecular weight polyurethane resin. On the other hand, the molecular weight is less than 1300〓〓〓〓〓
In this case, the particle size of the dispersion becomes large and tends to lack stability. In the present invention, the isocyanate-terminated hydrophobic urethane prepolymer used as the dispersion material is synthesized by a method known in polyurethane chemistry. A polyhydroxy compound having a hydroxyl group at the end and the polyisocyanate compound are combined with an excess of isocyanate groups at a ratio of NCO/OH=1.2 to 2.5 of 50 to 150.
It is obtained by reacting at a temperature of 1 to 10 hours. The polyhydroxy compounds used in the production of this hydrophobic urethane prepolymer are, for example, polyalkylene ether polyols containing no ethylene oxide units, polyethers (hereinafter referred to as hydrophobic polyalkylene ether polyols), polyester polyol copolymers, polyester polyols. etc., and the hydrophobic polyalkylene ether polyols are preferably polypropylene ether glycol, polytetramethylene ether glycol, polypropylene ether triol, and polyether. Polyester copolymers are polyester polyols obtained from aliphatic or aromatic dicarboxylic acids such as malonic acid, maleic acid, succinic acid, adipic acid, tartaric acid, phthalic acid, and terephthalic acid, and diethylene glycol, triethylene glycol, tetraethylene glycol, etc. and the polyester polyol contains the dicarbonate and ethylene glycol, propylene glycol,
Also included are polyester polyols obtained from glycols such as butylene glycol, hexamethylene glycol, neopentyl glycol, and the like, as well as polycaprolactone polyester polyols obtained by ring-opening polymerization of lactone. The above polyhydroxy compounds can be used alone or in a mixture of two or more, and mixtures of these with low molecular weight glycols, polyhydric alcohols such as glycerin, trimethylolpropane, pentaerythritol, etc. can also be used. The polyisocyanate compounds to be reacted with these polyhydroxy compounds are the same as the polyisocyanate compounds used in the production of the dispersant of the present invention described above. A hydrophobic urethane prepolymer having isocyanate groups at its ends can be obtained from the above polyhydroxy compound and an equivalent amount of a polyisocyanate compound. If desired, a small amount of a hydrophobic organic solvent inert toward isocyanate groups, such as triol, xylol, ethylene dichloride, trichloroethylene, trichloroethane, etc., may be used. The polyurethane resin aqueous dispersion of the present invention is produced in the following manner. (1) Add a reactive hydrophilic urethane prepolymer, which is a dispersant used in the present invention, to the hydrophobic urethane prepolymer, mix thoroughly, and then add an aqueous medium containing a chain extender therein, or Alternatively, conversely, a urethane prepolymer (mixed as described above) is added to an aqueous medium containing a chain extender, and the chain extender is added at the same time as dispersion to obtain a polyurethane aqueous dispersion. (2) Adding an aqueous solution of a reactive hydrophilic urethane prepolymer to a hydrophobic urethane prepolymer, or conversely, adding a hydrophobic urethane prepolymer to an aqueous solution of a reactive hydrophilic urethane prepolymer and adding a chain extender after dispersion leads to polymerization. An aqueous polyurethane dispersion is obtained, and if necessary, various additives such as various other surfactants, protective colloids, etc. may be added. When increasing the molecular weight of the polyurethane resin aqueous dispersion obtained here, as a chain extender,
Usually, water-hydrazine and various polyfunctional polyamines are used, such as ethylene diamine, propylene diamine, 1,6-hexamethylene diamine, 1,4-tetramethylene diamine, phenylene diamine, tolylene diamine, 4,
4'-diphenylmethanediamine, xylylenediamine, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, piperazine, 2-methylpiperazine alone or in combination Further, examples include mixtures of these polyamines, which are alkylated and partially amidated or imidized with fatty acids or polycarboxylic acids, and which have two or more active hydrogen atoms. The amount of the hydrophilic urethane prepolymer used as the dispersant used in the present invention is usually determined by the amount of the hydrophilic urethane prepolymer used as the dispersing agent.
The resin content is 2 to 30% by weight based on the polyurethane prepolymer. If the amount of the reactive hydrophilic urethane polymer used is less than 2% by weight based on the hydrophobic urethane prepolymer, coarse particles will be generated in the dispersion, resulting in a lack of stability. If the amount exceeds 30% by weight, the viscosity of the dispersion increases, making it impossible to obtain a dispersion with a high solids content, and at the same time, the mechanical properties of the dried film decrease when wet with water. The amount used is preferably 3 to 20% by weight. The content of ethylene oxide units based on the entire high molecular weight polyurethane resin is 1
Preferably it is ~15% by weight. The concentration of the aqueous polyurethane resin dispersion of the present invention, that is, the solid content is not particularly limited;
Approximately 20 to 65% by weight, preferably 40 to 65% by weight, considering dispersion stability, economy, industrial productivity, and other factors.
It is 55% by weight. The polyurethane resin aqueous dispersion of the present invention has excellent physical properties compared to conventional polyurethane resin aqueous dispersions, and is widely used in various applications, such as textiles, leather, synthetic leather, and synthetic fibers. It is used for adhesion, surface coating, and impregnation of plastic films, foams, metals, wood, and other materials, and exhibits excellent performance. Next, the present invention will be specifically explained with reference to Examples. Note that "%" or "%" in the middle of the sentence indicates parts by weight or weight %. Example 1 "Synthesis of reactive hydrophilic urethane prepolymer" 90 ethylene oxide units with an average molecular weight of 3700
1000 parts of random copolymerized polyether polyol containing ethylene oxide-propylene oxide and tolylene diisocyanate (2.4-/
2.6-=80/20) 93.2 parts at 100℃ in nitrogen atmosphere
After reacting for an hour, the isocyanate group content is 2.6
%, a viscosity of 3500 centipoise (35°C) was obtained. (hereinafter referred to as hydrophilic urethane prepolymer) "Synthesis of hydrophobic urethane prepolymer" 1,3-butanediol with an average molecular weight of 1000,
321.9 parts of tolylene diisocyanate (2.4-/2.6] = 80/20) was added to 1000 parts of polyester polyol consisting of 1,4-butanediol and adipic acid at 90 parts.
C. for 3 hours to obtain a hydrophobic urethane prepolymer with an NCO content of 5.1%. (Hereinafter referred to as hydrophobic prepolymer) A mixture of 100 parts of the hydrophobic prepolymer obtained above and 10 parts of hydrophilic prepolymer 1 was slowly added with 110 parts of water cooled to 10° C. while stirring vigorously. Furthermore, a 50% solution of 3.46 parts of ethylenediamine diluted with the same amount of water was gradually added to form a chain elongation polymer, with a concentration of 50.2% and a viscosity of 1580 centipoise (20
℃) and a high molecular weight urethane aqueous dispersion with a pH of 7.1 was obtained.
Note that the same effect can be obtained by adding a hydrophobic prepolymer to an aqueous solution of a hydrophilic prepolymer, stirring it, and then adding ethylenediamine. Example 2 "Synthesis of hydrophobic urethane prepolymer" 1000 parts of polypropylene polyether polyol with an average molecular weight of 1000 and tolylene diisocyanate
295.8 parts were reacted at 110℃ for 3 hours to obtain NCO content of 4.5
% hydrophobic urethane prepolymer was obtained. (Hereinafter referred to as hydrophobic prepolymer) 5 parts of the hydrophilic prepolymer was added to 100 parts of the hydrophobic prepolymer obtained above, and while stirring vigorously, 106 parts of water at 10°C in which 1 part of polyoxyethylene nonylphenol ether was dissolved. was added little by little to emulsify and disperse. Thereafter, while stirring with a homomixer, 11.6 parts of a 50% aqueous solution of 1,6-hexamethylene diamine was added, and a chain extension reaction was carried out for about 30 minutes. Concentration 50.1%, viscosity 420 centipoise (20℃),
A high molecular weight urethane aqueous dispersion with a pH of 7.8 was obtained. Example 3 "Synthesis of reactive hydrophilic urethane prepolymer" 80 ethylene oxide units with an average molecular weight of 4480
% of ethylene oxide-propylene oxide random copolymerized polyether polyol
1000 parts of dicyclohexylmethane-4,4'-diisocyanate were reacted with 117 parts of dicyclohexylmethane-4,4'-diisocyanate for 3 hours at 110°C in a nitrogen atmosphere to obtain an isocyanate group content (NCO) of 1.68% and a viscosity of 7800 centipoise (35°C).
A reactive hydrophilic urethane prepolymer was obtained. (hereinafter referred to as hydrophilic prepolymer) "Synthesis of hydrophobic urethane prepolymer" 1,3-butanediol with an average molecular weight of 1500,
3-isocyanate from 1,4-butanediol and adipic acid to 1000 parts of polyester polyol
267 parts of methyl-3,5,5-trimethylcyclohexyl isocyanate was reacted at 105°C for 3 hours to obtain a hydrophobic urethane prepolymer with an isocyanate group content (NCO) of 3.2% (hereinafter referred to as hydrophobic prepolymer). Polymerization 20 parts of the hydrophilic prepolymer were added to 100 parts of the hydrophobic prepolymer, and while stirring vigorously, 180 parts of water at 10°C or lower was added little by little to emulsify. Thereafter, while stirring with a homomixer, 16.2 g of a 40% aqueous solution of 3-aminomethyl-3,5,5-trimethylcyclohexylamine was added, and a chain extension reaction was carried out for about 1 hour. A high molecular weight urethane aqueous dispersion having a concentration of 40.8%, a viscosity of 250 centipoise (20°C), and a pH of 7.5 was obtained. Example 4 “Synthesis of hydrophobic urethane prepolymer” Neopentyl glycol with an average molecular weight of 1000
1.6 445 parts of dicyclohexylmethane-4,4'-diisocyanate was added to 1000 parts of polyester polyol consisting of hexanediol and adipic acid at 105°C.
After reacting for 4 hours, 361 parts of toluene was added and stirred and mixed until homogeneous to obtain a hydrophobic urethane prepolymer solution with an isocyanate group content (NCO) of 3.2% and a solid content of 80%. (Hereinafter referred to as hydrophobic prepolymer) "Emulsion polymerization" 10 parts of hydrophilic prepolymer was added to 100 parts of hydrophobic prepolymer, and while stirring vigorously, 1 part of polyoxyethylene nonyl phenol ether was dissolved in a solution of 10°C or lower. 100 parts of water was added little by little to emulsify. Then, while stirring with a homomixer, 5.7 parts of 40% ethylenediamine aqueous solution was added.
The chain extension reaction was carried out for about 1 hour. A high molecular weight urethane aqueous dispersion having a concentration of 40.3%, a viscosity of 930 centipoise (20°C), and a pH of 7.9 was obtained. Comparative Example 1 While vigorously stirring 100 parts of a hydrophobic prepolymer, 10 parts of polyoxyethylene nonylphenol ether was dissolved. 125 parts of water at 10°C or lower was added little by little to emulsify. Then, while stirring with a homomixer, add a 40% aqueous solution of ethylenediamine.
5.7 parts were added, and the chain elongation reaction was carried out for about 1 hour. It was a high molecular weight urethane aqueous dispersion with a concentration of 40.2%, a viscosity of 580 centipoise (20°C), and a pH of 7.8. Table 1 shows a performance comparison of the high molecular weight urethane aqueous dispersions obtained in the above Examples and Comparative Examples.

[Table] Test method and evaluation criteria Γ Stationary stability Collect each urethane aqueous dispersion in a test tube, leave it at room temperature for one month, and visually judge the degree of sedimentation of emulsion particles at the bottom (evaluation criteria) ◎ : No sedimentation particles at all ○ : A small amount of coarse particles sedimentation × : A large amount of emulsion particles sedimentation Γ Dilution stability The emulsion concentration is diluted with water to 1%, and immediately after dilution, the presence or absence of suspended matter is judged visually (evaluation criteria) ) ○; No floating objects〓〓〓〓〓
× Floating matter generation Γ Film forming ability Apply urethane aqueous dispersion to a thickness of 0.3 m/m on a glass plate, leave it to dry in a windless oven at 100°C for 30 minutes, and check the film formation state with the naked eye. Judgment (evaluation criteria) ◎: Formation of uniform transparent film with no cracks ○: Formation of transparent film although there are some cracks ×: Formation of opaque film with many cracks Γ Mechanical properties of film Urethane aqueous dispersion on glass plate After vacuum degassing,
Coated with a thickness of 0.3m/m and adjusted to a windless condition
After drying in an oven at 100°C for 10 minutes, the film was heat-treated at 150°C for 5 minutes and its physical properties were measured using Autograph IS-500 manufactured by Shimadzu Corporation. 〓〓〓〓〓

Claims (1)

[Scope of Claims] 1. When producing an aqueous urethane resin dispersion consisting of an isocyanate-terminated hydrophobic urethane prepolymer, a dispersant, water, and a chain extender, 40 to 40 to 50% of ethylene oxide alone is contained in one molecule chain as a dispersant. 98% by weight
1. A method for producing an aqueous polyurethane resin dispersion, which comprises using a reactive hydrophilic urethane prepolymer containing a polyurethane resin and having an isocyanate group at its end. 2. When dispersing a hydrophobic urethane prepolymer in water, the hydrophobic urethane prepolymer and the hydrophilic urethane prepolymer are sufficiently mixed, and an aqueous medium containing a chain extender is added thereto, or a chain extender is added to the aqueous medium containing a chain extender. The method for producing an aqueous polyurethane resin dispersion according to claim 1, characterized in that the mixed urethane prepolymer is added and mixed into an aqueous medium containing a polyurethane resin. 3. The method for producing an aqueous polyurethane resin dispersion according to claim 1, which comprises adding a chain extender after mixing the aqueous solution of the hydrophilic urethane prepolymer and the hydrophobic urethane prepolymer.