JP2503982B2 - Method for producing modified polyurethane aqueous dispersion - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a new method of modifying a stable aqueous dispersion based on polyurethane, which has particularly good film-forming ability and excellent mechanical properties. The present invention relates to a method for producing a modified polyurethane aqueous dispersion having dynamic strength, water resistance, solvent resistance, heat resistance, and adhesion to various substrates.

[Prior Art] In recent years, from the viewpoints of pollution, environmental pollution, etc., there has been an increasing interest in water-based resins in place of conventional organic solvent-based resins. Among them, water-based polyurethane resins have excellent mechanical properties. , For example, the public information of Japanese Patent Publication No. Sho 49-16601,
JP-A-47-11938 or fiber, 27 , 481 (1975)
In addition to the use as a treatment agent for artificial leather and fibers as described in (1), it has been used in a wide range of fields as an adhesive for vinyl chloride base materials or glass.

However, in such a polyurethane aqueous dispersion, many hydrophilic groups such as carboxyl groups are introduced into polyurethane in order to stably disperse in water. For this reason,
A dry film obtained from such a polyurethane aqueous dispersion,
In particular, in addition to durability such as water resistance, solvent resistance, heat resistance, etc., toughness, adhesiveness, etc. are lacking, in order to bring out various physical properties at a practical level, melamine resin, epoxy resin, aziridine compound, etc. are generally used. It is put to practical use by blending a crosslinking agent.

[Problems to be Solved by the Invention] However, when the above-mentioned crosslinking agent and, if necessary, a catalyst for accelerating the crosslinking are blended and used, the crosslinking agent reacts with the passage of time, Since the viscosity increases and finally gels, there is a restriction that the pot life is limited. Further, after processing and drying using a compounding liquid containing the crosslinking agent, it is usually necessary to perform a heat treatment to complete the crosslinking reaction of the crosslinking agent and the polyurethane resin. When it is used, there are many restrictions in use such as pot life and heat treatment, and there is a problem that the use is limited.

[Means for Solving Problems] From such a viewpoint, the inventors of the present invention have produced the modified polyurethane aqueous dispersion which overcomes the above-mentioned drawbacks and has the same film physical properties as those when the crosslinking agent is blended and processed. As a result of diligent research on the method, it was found that by reacting a polyepoxy compound or a polyaziridine compound having an equivalent amount of carboxyl groups in polyurethane or less with an aqueous dispersion of polyurethane in an aqueous medium, stable and film-forming without gelation. It was found that a modified polyurethane aqueous dispersion having excellent properties and various physical properties of the coating can be obtained, and the present invention has been completed.

That is, according to the present invention, when the carboxyl group-containing polyurethane aqueous dispersion (A) is modified with a polyepoxy compound or polyaziridine compound (B) having at least two oxirane rings or aziridine rings in the molecule, A polyepoxy compound or polyaziridine compound (B) having an equivalent amount of a carboxyl group or less contained in the polyurethane aqueous dispersion (A) is used, and the polyepoxy compound or polyaziridine compound is used in the polyurethane aqueous dispersion (A). The present invention provides a method for producing a modified polyurethane aqueous dispersion, which comprises adding (B) and then mixing and dispersing the mixture under stirring until the reaction is completed.

The polyurethane aqueous dispersion used in the present invention is a self-dispersion type aqueous dispersion having a solid content of preferably 5 to 60% by weight, more preferably 10 to 50% by weight, and preferably an emulsifier. It is an aqueous polyurethane dispersion having a carboxyl group bonded to the skeleton.

The self-dispersion polyurethane aqueous dispersion suitable as the polyurethane aqueous dispersion used in the present invention is a polyol such as a polyester polyol or a polyether polyol and an aromatic or fat, an alicyclic diisocyanate and, if necessary, a chain extender. The polyurethane resin obtained from 1. is stably dispersed or dissolved in water without using an emulsifier. The following methods are known as dispersion or dissolution methods.

(1) A method of imparting hydrophilicity by introducing an ionic group such as a sulfo group or a carboxyl group into a side chain or terminal of a polyurethane polymer, and dispersing or dissolving in water by self-emulsification.

(2) A method in which a water-soluble polyol such as polyethylene glycol is used as a part of the polyol which is the main raw material of polyurethane to prepare a hydrophilic polyurethane resin, which is dispersed or dissolved in water.

The self-dispersion polyurethane aqueous dispersion used in the present invention is not limited to the above-mentioned single dispersion or dissolution method, and a mixture obtained by each method can be used.

The method of introducing a carboxyl group into the polyurethane resin may be any conventionally known method, for example, [Wherein R represents an alkyl group having 1 to 3 carbon atoms], a method of using a pendant carboxyl group-containing polyester polyol obtained by copolymerizing a compound represented by the formula as a glycol component when synthesizing a polyester,
Alternatively, the chain extender may be a method using a chain extender containing a pendant carboxyl group represented by the general formula (I), and the compound represented by the general formula (I) may be 2,2-dimethylol. Propionic acid, 2,2-dimethylol butyric acid, 2,2-dimethylol valeric acid and the like can be mentioned.

In addition, as a method of introducing a carboxyl group other than the above,
JP-B-52-3238 (method of using two carboxyl group-containing aromatic diamines as a chain extender), JP-A-57 / 57
-165420 (method using half ester from polyhydroxy compound and dicarboxylic acid anhydride as chain extender), JP-B-53-7479 (reacting excess polyalkylene polyamine with isocyanate terminated prepolymer) Polyurethane urea polyamine, followed by addition of trimellitic anhydride), JP-B-52-40677 (synthesizing a high acid value polyester intermediate from polyhydric alcohol and polybasic acid, the equivalent of the hydroxyl group or less Method of reacting with polyisocyanate) and the like.

The content of the carboxyl group contained in the aqueous polyurethane dispersion obtained in this manner is determined by the reaction with the polyepoxy compound or the polyaziridine compound so that the crosslinking effect can be obtained while maintaining the stability of the aqueous acid solution and the film forming property. The content is preferably in the range necessary for expression, and is preferably 0.5 to 20% by weight (solid content ratio) with respect to the polyurethane resin. In addition, examples of the base used for neutralizing the carboxyl group include ammonia, organic amines, hydroxides of alcal metals or alkaline earth metals, and the like.

Further, not only a carboxyl group alone, but also a sulfo group, a method of making a self-emulsifying property by introducing a polyethylene oxide group may be any conventionally known method, for example, ethylenediamine-2-ethanesulfonic acid, 2-oxyethanesulfonic acid, Phenolsulfonic acid, sulfobenzoic acid, 1,3-phenylenediamine-4,6-disulfonic acid,
4,6-diaminobenzene-1,3-disulfonic acid, 2,4-diaminotoluene-5-sulfonic acid and the like and salts and derivatives of these sulfonic acid-containing compounds; molecular weight 300 to 10,000
Of polyethylene glycol, ethylene oxide / propylene oxide copolymers and monoalkyl ethers of these polyoxyalkylene glycols with other raw materials during the urethanization reaction, and the above-mentioned sulfo group- and polyethylene oxide group-containing compounds. Examples thereof include a method of using a polyester polyol obtained by copolymerization as one component of a polyol, and the like, which can be used together with the method of introducing the carboxyl group.

The content of such sulfo group and polyethylene oxide group is preferably in the range necessary for maintaining the stability and film forming property of the aqueous dispersion during and after the reaction with the polyepoxy compound or the polyaziridine compound. The solid content of the polyurethane resin is preferably 0.01 to 5% by weight and 0.1 to 20% by weight, respectively.

The polyol used in the production of the polyurethane aqueous dispersion of the present invention has a molecular weight of 200 to 10,000, preferably 300 to 10,000.
5000 is preferable, and conventionally known polyester and polyether as well as polycarbonate, polyester amide, polyacetal, polythioether, polybutadiene glycol and the like can be mentioned.

As the polyester, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol,
Triethylene glycol, tetraethylene glycol,
Polyethylene glycol (molecular weight 300-6000), dipropylene glycol, tripropylene glycol, 1,4-
Glycol components such as cyclohexanediol, 1,4-cyclohexanedimethanol, bisphenol A, hydroquinone and their alkylene oxide adducts, and succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,
4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalene acid,
Biphenylcarboxylic acid, 1,2-bis (phenoxy) ethane-p, p'-dicarboxylic acid and anhydrides or ester-forming derivatives of these dicarboxylic acids; p-hydroxybenzoic acid, p- (2-hydroxyethoxy) benzoic acid And a polyester obtained by a dehydration condensation reaction with an acid component such as an ester-forming derivative of hydroxycarboxylic acid, a polyester obtained by a ring-opening polymerization reaction of a cyclic ester compound such as ε-caprolactone, and a copolyester thereof. Can be mentioned.

As the polyether, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, trimethylene glycol, 1,3-butylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, glycerin, sorbitol, sucrose, Active hydrogen atoms such as aconitic acid, trimellitic acid, hemimellitic acid, phosphoric acid, ethylenediamine, propylenediamine, diethylenetriamine, triisopropanolamine, pyrogallol, dihydroxybenzoic acid, hydroxyphthalic acid, 1,2,3-propanetrithiol Ethylene oxide, propylene oxide, butylene oxide, as one or more initiators of compounds having at least two
Examples thereof include those obtained by addition-polymerizing one or more monomers such as styrene oxide, epichlorohydrin, tetrahydrofuran and cyclohexylene by a conventional method.

As the chain extender used with the above polyol,
For example, glycols such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, hexamethylene glycol, neopentyl glycol and the like; ethylenediamine, propylenediamine,
Hexamethylenediamine, phenylenediamine, tolylenediamine, diphenyldiamine, diaminodiphenylmethane, diaminocyclohexylmethane, piperazine,
Diamines such as isophoronediamine; and hydrazine.

Examples of the polyisocyanate compound used in the production of the polyurethane aqueous dispersion of the present invention include 2,4-
Tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylene methane diisocyanate, tetramethyl diisocyanate,
Hexamethylene diisocyanate, xylylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate, 1,4-cyclokihexylene diisocyanate, 4,4 '
-Dicyclohexylmethane diisocyanate, 3,3'-
Dimethyl-4,4'-biphenylene diisocyanate, 3,
Examples thereof include 3'-dimethoxy-4,4'-biphenylene diisocyanate, 3,3'-dichloro-4,4'-biphenylene diisocyanate, 1,5-naphthalene diisocyanate and 1,5-tetrahydronaphthalene diisocyanate.

As the polyepoxy compound having at least two oxirane rings in the molecule used in the present invention,
For example, structural formula [I]: An epichlorohydrin / bisphenol A type epoxy resin represented by the structural formula [II]: (R: CH ₂ CH ₂ −, −CH ₂ CH (CH ₃ ) −, R ′: H, −CH ₃ ), a chain epoxy resin, structural formula [III] A novolac type epoxy resin represented by the structural formula [IV]: Flame-retardant epoxy resin represented by the structural formula [V]: Examples of the cycloaliphatic epoxy resin, dimer acid-based diglycidyl ester and the like and organic solvent liquids thereof. Further, a nonionic or anionic emulsifier is added to the above polyepoxy compound to emulsify and disperse in epoxy resin emulsion or ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, glycerin, tri Methylolethane, trimethylolpropane,
Polyglycidyl ethers of polyhydroxy compounds such as diglycerin, 3-methylpentanetriol, polyglycerin, sorbitol, glycerin ethylene oxide adducts; water-soluble epoxies of diglycidyl esters of dicarboxylic acids such as succinic acid, adipic acid and terephthalic acid Resins may be mentioned. Of these, liquid or emulsion type polyepoxy compounds are preferable in the production method of the present invention.

Examples of the polyaziridine compound having at least two or more aziridine rings in the molecule used in the present invention include, for example, 2,4,6-tris (1′-aziridinyl) -1,
3,5-triazine, ω-aziridinylpropionic acid-2,2
-Dihydroxymethyl-butanol triester, 2,4,
6-Tris (2-methyl-1-aziridinyl) -1,3,5-
Triazine, 2,4,6-tris (2-ethyl-1-aziridinyl) -1,3,5-triazine, 4,4'-bis (ethyleneiminocarbonylamino) diphenylmethane, bis (2
-Ethyl-1-aziridinyl) benzene-1,3-dicarboxylic acid amide, tris (2-ethyl-1-aziridinyl) benzene-1,3,5-tricarboxylic acid amide, bis (2-ethyl-1-aziridinyl) sebacine Acid amide,
1,6-bis (ethylene imino carbonylamino) hexane, 2,4-diethylene ureido toluene, 1,1'-carbonyl - bis - ethylenimine, polymethylene - bis - Echirun'yuria _{(C 2 ~C 4), N} , N ' -Bis (4,6-diethyleneimino-1,3,5-triazin-2-yl) -hexamethylenediamine and the like.

The amount of the polyepoxy compound or polyaziridine compound used in the present invention is such that the amount of the epoxy group or aziridinyl group in these compounds is not more than the equivalent of the carboxyl group contained in the polyurethane aqueous dispersion, that is, [epoxy group or aziridinyl group]. / Carboxyl group ≤ 1
It is necessary to be within the range that satisfies (equivalent ratio),
It is preferably 0.01 to 1 (equivalent ratio). The ratio of epoxy group or aziridinyl group to carboxyl group is 0.
If it is less than 01 equivalent ratio, the modification effect of the polyurethane aqueous dispersion by the polyepoxy compound or the polyaziridine compound,
For example, the effect of improving heat resistance, water resistance, solvent resistance, etc. may be low. On the other hand, when the ratio exceeds 1 equivalent, excess polyepoxy compound or polyaziridine compound remains with respect to the carboxyl group, so that agglomerates are generated during the reaction or gelation is complete, and the resulting modification It is not suitable because the aqueous polyurethane dispersion has poor stability over time.

When carrying out the method according to the present invention, the polyepoxy compound or the polyaziridine compound is added to the carboxyl group-containing polyurethane aqueous dispersion to be modified in the present invention, and the resulting mixture is sufficiently and uniformly mixed with stirring, and then if necessary. To 100 ° C to complete the reaction. At this time, the reaction temperature can be arbitrarily selected, but is preferably 20 to 80 ° C. It is preferable to stir until the reaction is complete. or,
In carrying out the method of the present invention, a nonionic or anionic emulsifier may be used in combination in order to maintain the stability of the polyurethane aqueous dispersion during or after the reaction.

[Effects of the Invention] The modified polyurethane aqueous dispersion obtained by the method of the present invention contains vinyl chloride,
Various plastics such as nylon, polyester, polyurethane; textile products, synthetic leather products or aluminum,
Not only does it have excellent adhesion to metals such as copper and iron, paper, wood, glass, etc., stability of aqueous dispersions, and film forming properties, but it does not require the use of cross-linking agents like conventional polyurethane aqueous dispersions. Has excellent mechanical strength, water resistance, solvent resistance, heat resistance, and other durability. Therefore, it is possible to develop into various applications without being restricted by pot life, high temperature heat treatment, etc., which have been problems when using conventional crosslinking agents, for example, treatment agents for fiber / synthetic products, It can be widely used as an adhesive for various substrates, a coating agent, a water-based paint, a water-based ink, or a sizing agent. The excellent effect that is the basis for enabling application to such a wide range of applications is that a uniform and tough film is formed at a temperature much lower than the softening temperature of the film (flow start temperature by the high flow tester). It is a point that can be formed, which is an unexpected effect.

Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited thereto. In the present invention, parts and% are by weight unless otherwise specified.

Reference Example 1 1660 parts of isophthalic acid, 3304 parts of hexamethylene glycol, neopentyl glycol while introducing nitrogen gas in a reactor equipped with a thermometer, a nitrogen gas introduction tube, and a stirrer.
Charge 1352 parts and 0.5 parts of dibutyltin oxide 180 ~
After esterification at 220 ℃ for 5 hours, until acid value becomes 0.5 23
The polycondensation reaction was carried out at 0 ° C. for 6 hours. Cool to 120 ° C,
Adipic acid 5840 parts, 2,2-dimethylolpropionic acid 201
0 part was added, the temperature was raised again at 170 ° C., and the reaction was carried out at this temperature for 20 hours to obtain a pendant carboxyl group-containing polyester polyol having a hydroxyl value of 54.2 and an acid value of 68.6.

After dehydrating 1035 parts of the above polyester polyol at 100 ° C. under reduced pressure and then cooling to 70 ° C., 397 parts of ethyl acetate was added and mixed thoroughly with stirring, and then 157 parts of tolylene diisocyanate was added and reacted at 70 ° C. for 4 hours. 30.8 parts ethylenediamine dissolved in 2560 parts of the prepolymer solution obtained by adding 795 parts of methyl ethyl ketone to the prepolymer of the terminal isocyanate group thus obtained and diluting it,
After reacting with 127.8 triethylamine, the solvent was further removed under reduced pressure to obtain a transparent colloidal aqueous dispersion having a nonvolatile content of 30% and a pH of 8.0.

Reference Example 2 In the same manner as in Reference Example 1, polypropylene glycol having a molecular weight of 1000 was reacted with 2,2-dimethylolpropionic acid and tolylene diisocyanate at 1/1 / 3.2 (molar ratio) to form a prepolymer, The solution was reacted with an aqueous solution of anhydrous piperazine and triethylamine, the solvent was removed under reduced pressure, and a milky white water dispersion liquid having a nonvolatile content of 30% and a pH of 7.8 was obtained.

Reference example 3 terephthalic acid / isophthalic acid / adipic acid / ethylene glycol / neopentyl glycol 30/30/40/50/50
(Molar ratio) Copolyester polyol (acid value 0.
2, hydroxyl value 93.0) with 2,2-dimethylolpropionic acid and hexamethylene diisocyanate at 1/1/2 (molar ratio) in methyl ethyl ketone to urethanize and then neutralize with ammonia water to give a nonvolatile content of 20 % Transparent colloidal water dispersion was obtained.

Examples 1 to 3 and Comparative Example 1 1000 parts of the polyurethane aqueous dispersion obtained in Reference Example 1 was placed in a reactor equipped with a thermometer and a stirrer, and stirred with Epicron 850 (Dainippon Ink and Chemicals, Inc. ), Average epoxy equivalent 189), Denacol EX-320 (Nagase & Co., Ltd., epoxy equivalent 130), Chemitite PZ-33.
(Nippon Shokubai Kagaku Co., Ltd., aziridine equivalent 142)
The mixture was added at the ratio shown in the table and reacted at 60 ° C. for 12 hours to obtain a modified polyurethane aqueous dispersion. The resulting aqueous dispersion was allowed to stand for 6 months and then observed for appearance changes. The results are shown in the stability section of the aqueous dispersion in Table 1. Further, these aqueous dispersions were spread in a film form on a polypropylene sheet and dried at 80 ° C., and the following tests were conducted on the films obtained, and the results shown in Table 1 were obtained.

(1) Strength and Elongation of Film The film was punched out with a dumbbell No. 2 type and measured with an autograph S-100 manufactured by Shimadzu Corporation at a tensile strength of 300 mm / min.

(2) Flow start temperature The film was measured with a high-performance flow tester (1 mmφ × 1 mml) at a temperature of 3 deg / min from room temperature under a load of 10 kg.

(3) Solvent resistance The film was cut into 5 cm x 5 cm and measured by area swelling after being immersed in each solvent for 24 hours.

Examples 4 to 6 and Comparative Example 2 Modified polyurethane aqueous dispersions were obtained in the same manner as in Examples 1 to 3 except that the polyurethane aqueous dispersion of Reference Example 2 was used, and the physical properties of the film were measured. Table 2 shows the results.

Examples 7, 8 and Comparative Examples 3, 4 Modified polyurethane aqueous dispersions were obtained in the same manner as in Examples 1 to 3 except that the polyurethane aqueous dispersion of Reference Example 3 was used, and the film physical properties were measured. The results are shown in Table 3.

From the above results, it is recognized that the modified polyurethane aqueous dispersions of the present invention all have excellent physical properties.

Claims (1)

(57) [Claims] 1. A carboxyl group-containing polyurethane aqueous dispersion (A) is modified with a polyepoxy compound or polyaziridine compound (B) having at least two oxirane rings or aziridine rings in the molecule, wherein A polyepoxy compound or polyaziridine compound (B) having an equivalent amount of a carboxyl group or less contained in the polyurethan aqueous dispersion (A) is used, and the polyepoxy compound or polyaziridine compound is used in the polyurethane aqueous dispersion (A). A method for producing a modified polyurethane aqueous dispersion, which comprises adding (B) and then mixing and dispersing the mixture under stirring until the reaction is completed.