JP4616977B2 - Method for producing polyurethane resin solution - Google Patents

Description

【００７７】
表１から明らかなように、本発明の実施例１〜５のポリウレタン樹脂溶液は比較例１〜２に比べ溶液粘度安定性が著しく良好で、しかも得られたフィルムの強伸度物性も高い水準にある。一方、比較例１〜２のポリウレタン樹脂溶液は溶液粘度安定性に乏しく実用に供し得ない。
【００７８】
【発明の効果】
本発明の方法で得られるポリウレタン樹脂溶液は溶液粘度安定性に優れ、長期間の保管後においても、製造直後とほとんど同等の溶液性状を保持する。
【００７９】
上記効果を奏することから本発明の方法で得られるポリウレタン樹脂溶液は種々の用途、例えば、人工皮革、合成皮革、各種のコート材料、弾性繊維等に用いられる原料として特に有用である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a polyurethane resin solution by a batch method. More specifically, the present invention relates to a method for producing a polyurethane resin solution that is excellent in solution stability and can be suitably used for various applications.
[0002]
[Prior art]
Conventionally, rubber excellent in elastic fibers, elastic films, various molded articles in the form of elastomers, surface coatings such as artificial leather surface coatings and various paints, impregnating agents, etc., using a polyurethane resin solution having substantially no crosslinked structure Various articles having a shape elasticity have been manufactured. This polyurethane resin solution is generally produced by reacting an organic diisocyanate with a relatively high molecular weight diol and a chain extender in a polar solvent, and then a molded product is produced by removing the solvent.
[0003]
However, after producing the polyurethane resin solution, the instability of the polyurethane resin solution, such as the cloudiness of the transparent solution or the increase in the viscosity, or the depolymerization and the decrease in the viscosity when the solution is heated, There are various problems to be solved in order to produce products efficiently industrially, such as lowering the moldability and physical properties of the molded product and limiting the usable time of the polyurethane resin solution.
[0004]
In order to solve these problems, as a method of stabilizing the viscosity of the polyurethane resin solution, for example, a method of adding an amine and an organic acid or an amine salt of an organic acid (Japanese Patent Publication No. 41-3472), water A method of performing a chain extension reaction in a polar solvent containing (Japanese Examined Patent Publication No. 44-22311), a method of producing a polyurethane polymer solution using an alicyclic diamine, an aromatic dimethylamine, and a substituted iminobisaliphatic amine (Japanese Patent Publication) 49-40006), a method for producing a polyurethane polymer solution using metal acetylacetone (Japanese Patent Laid-Open No. 47-15498), a method for stabilizing a polyurea elastomer solution by adding lithium formate, sodium acetylacetone, or the like ( JP-A-48-12347), poly using lithium salt, aliphatic or alicyclic chain terminator A polyurethane resin solution by specifying the addition conditions of a retaneurea elastomer (JP-A-3-139514), a symmetric diamine, a polyurethane elastic fiber using an asymmetric diamine (JP-A-3-279415), hydrazine and a diamine solution There are known methods for producing the above (Japanese Patent Laid-Open No. 50-78698) and the like, but these methods have slightly improved the stability of the viscosity and the hue, but have not yet been satisfied.
[0005]
Regarding the stabilization of the viscosity of the polyurethane resin solution during heat storage, Japanese Patent Publication No. 47-35317 discloses that the amount of chain extender is less than the equivalent of isocyanate (hereinafter abbreviated as NCO) group and the remainder is chain extended with water. However, there is a drawback that the viscosity decreases until the viscosity is stabilized, and the stabilized viscosity is about half of the viscosity immediately after the synthesis, which is not satisfactory.
[0006]
[Problems to be solved by the invention]
The present invention provides a polyurethane resin solution that solves the above-mentioned problems and can be suitably used for a wide variety of applications, is transparent, has good viscosity stability, has no coloring or thickening, and does not cause depolymerization due to heat. It aims at providing the manufacturing method of the polyurethane resin solution which can be obtained.
[0007]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have found that a decrease in solution physical properties such as coloring, thickening, and thermal stability is a side reaction that occurs simultaneously with the urethanization reaction, that is, NCO in the urethane bond. The formation of a burette bond formed by reaction of an NCO group with an allophanate bond or urea bond formed by reaction of a group causes the viscosity to increase during storage of the polyurethane resin solution or to decrease stability during storage by heating. I found out. Furthermore, as a result of intensive studies on methods for reducing these side reactions, during the urethanization reaction, the urethanization reaction is performed in the presence of a specific amount of monohydric alcohol with respect to the NCO group, and the NCO remaining in the reaction system at the end of the reaction. By stopping the reaction by adding an excessive amount of monohydric alcohol or monoamine to the group, there is no deterioration of the solution properties such as coloring, thickening, thermal stability, etc., and the molded product after removing the solvent The inventors have found that a polyurethane resin solution having no deterioration in physical properties can be obtained, and have reached the present invention.
[0008]
That is, the method for producing the polyurethane resin solution of the present invention includes an organic diisocyanate (a), a high molecular diol (b) having a number average molecular weight of 500 to 5,000, a low molecular diol (c) having a molecular weight of 300 or less, and a molecular weight of 200 or less. When the monohydric alcohol (d1) is reacted in an organic solvent, the monohydric alcohol (d1) is 0.001 to the total of the high molecular diol (b) and the low molecular diol (c). A polyurethane resin characterized by adding a monohydric alcohol (d2) at a stage where the content of free isocyanate groups per resin component is 0.01 to 0.1% by weight, with a content of .about.0.03 equivalent. It is a manufacturing method of a solution.
[0009]
Alternatively, an organic diisocyanate (a), a high molecular diol (b) having a number average molecular weight of 500 to 5,000, a low molecular diol (c) having a molecular weight of 300 or less, and a monohydric alcohol (d1) having a molecular weight of 200 or less are mixed with an organic solvent. In the reaction, the monohydric alcohol (d1) is 0.001 to 0.03 equivalent to the total of the high molecular diol (b) and the low molecular diol (c). In the method for producing a polyurethane resin solution, monoamine (d3) is added when the free isocyanate group content per resin content becomes 0.01 to 0.1% by weight.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, as the organic diisocyanate (a), those conventionally used for polyurethane production can be used. Examples of such organic diisocyanates include aromatic diisocyanates having 6 to 20 carbon atoms (excluding carbon in the NCO group, the same shall apply hereinafter), aliphatic diisocyanates having 2 to 18 carbon atoms, and alicyclic diisocyanates having 4 to 15 carbon atoms. , Araliphatic diisocyanates having 8 to 15 carbon atoms, modified products of these diisocyanates (carbodiimide-modified products, urethane-modified products, uretdione-modified products, etc.) and mixtures of two or more thereof.
[0011]
Specific examples of the aromatic diisocyanate include 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,4′-diphenylmethane diisocyanate, 4, 4′-diphenylmethane diisocyanate (hereinafter abbreviated as MDI), 4,4′-diisocyanatobiphenyl, 3,3′-dimethyl-4,4′-diisocyanatobiphenyl, 3,3′-dimethyl-4, 4'-diisocyanatodiphenylmethane, 1,5-naphthylene diisocyanate, etc. are mentioned.
[0012]
Specific examples of the aliphatic diisocyanate include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethylcaproate, Examples thereof include bis (2-isocyanatoethyl) carbonate and 2-isocyanatoethyl-2,6-diisocyanatohexanoate.
[0013]
Specific examples of the alicyclic diisocyanate include isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, and bis (2-isocyanatoethyl) -4-cyclohexylene-1,2. -Dicarboxylate, 2,5-norbornane diisocyanate, 2,6-norbornane diisocyanate and the like.
[0014]
Specific examples of the araliphatic diisocyanate include m-xylylene diisocyanate, p-xylylene diisocyanate, α, α, α ′, α′-tetramethylxylylene diisocyanate and the like.
[0015]
Among these, aromatic diisocyanates are preferable and MDI is particularly preferable from the viewpoint of improving the strength of the final product and obtaining excellent heat resistance in various applications.
[0016]
As the polymer diol (b) used in the present invention, for example, polyalkylene ether diol (b1), polyester diol (b2), polybutadiene diol (b3) and a mixture of two or more of these are preferably used.
[0017]
The number average molecular weight of the polymer diol (b) is preferably 500 to 5,000, more preferably 700 to 4,500, and still more preferably 1,000 to 4,000.
[0018]
Examples of the polyalkylene ether diol (b1) include compounds having a structure in which an alkylene oxide (hereinafter abbreviated as AO) is added to a dihydric alcohol, and mixtures of two or more thereof.
[0019]
Examples of the dihydric alcohol include ethylene glycol (hereinafter abbreviated as EG), propylene glycol, 1,3-butylene glycol, 1,4-butanediol (hereinafter abbreviated as 14BG), and 1,6-hexane. Aliphatic dihydric alcohols having 2 to 12 carbon atoms such as diol, diethylene glycol (hereinafter abbreviated as DEG), neopentyl glycol, dodecanediol, or, for example, 1,4-cyclohexanediol, bis (hydroxymethyl) cyclohexane, etc. C6-C10 alicyclic dihydric alcohol or C8-C20 such as xylylene glycol, bis (hydroxyethyl) benzene, bis (hydroxyethoxy) benzene, bisphenol A ethylene oxide adduct, etc. Aromatic ring-containing dihydric alcohol It is preferably used. Two or more dihydric alcohols are preferably used in combination.
[0020]
Examples of AO added to the dihydric alcohol include ethylene oxide (hereinafter abbreviated as EO), propylene oxide (hereinafter abbreviated as PO), 1,2-butylene oxide, 2,3-butylene oxide, 1,3- Examples include butylene oxide, tetrahydrofuran (hereinafter abbreviated as THF), 3-methyltetrahydrofuran (hereinafter abbreviated as 3M-THF), styrene oxide, α-olefin oxide, epichlorohydrin, and the like.
[0021]
AO may be used alone or in combination of two or more. In the case of using two or more, AO may be block addition or random addition such as chip type, balance type, and active secondary type, and is a mixed system of block addition and random addition. For example, chips after random addition, that is, preferably 0 to 50% by weight, more preferably 5 to 40% by weight of ethylene oxide chains are arbitrarily distributed in the molecule, preferably 0 to 30% by weight. %, More preferably 5 to 25% by weight of ethylene oxide chains may be chipped at the molecular ends.
[0022]
Among these AOs, in various applications, from the viewpoint of increasing the elongation of the final product, being flexible, and improving recoverability, in particular, THF alone, EO and THF combined, THF and A combination of 3M-THF (in the case of combination, random addition, block addition, and a mixture of both) may be preferable.
[0023]
Specific examples of the polyalkylene ether diol (b1) include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol (hereinafter abbreviated as PTMG), poly-3-methyltetramethylene ether glycol, THF / EO copolymerized diol, THF / 3M-THF copolymerized diol. Among these, PTMG, THF / EO copolymerized diol, THF / 3M-THF copolymerized diol and the like are preferable.
[0024]
The addition of AO to the dihydric alcohol can be carried out in the usual manner, without catalyst or in the presence of a catalyst (alkali catalyst, amine catalyst, acidic catalyst, etc.) (particularly at the latter stage of AO addition). It is preferably carried out in one or more stages under normal pressure or increased pressure.
[0025]
The number average (calculated from OH number) molecular weight of the polyalkylene ether diol (b1) is preferably 500 to 5,000, more preferably 700 to 4,500, and still more preferably 1,000 to 4,000. It is.
[0026]
The primary hydroxyl group content of the polyalkylene ether diol (b1) is preferably 0 to 100 from the viewpoint of improving the reactivity even when no catalyst is used and preventing problems such as residual catalyst due to the addition of the catalyst. %, More preferably 30 to 100%, still more preferably 50 to 100%, and most preferably 70 to 100%.
[0027]
The polyester diol (b2) includes a condensed polyester diol obtained by reacting a dihydric alcohol and / or a polyalkylene ether diol having a molecular weight of 1,000 or less and a dicarboxylic acid, a polylactone diol obtained by ring-opening polymerization of a lactone, Polycarbonate diol obtained by reacting a dihydric alcohol with a carbonic acid diester of a lower alcohol (such as methanol) is preferably included.
[0028]
Examples of the dihydric alcohol include those similar to the dihydric alcohol exemplified as the starting material of the polyalkylene ether diol (b1).
[0029]
Examples of the polyalkylene ether diol having a molecular weight of 1,000 or less include polytetramethylene ether glycol, polypropylene glycol, polyethylene glycol, and a mixture of two or more thereof.
[0030]
Moreover, as dicarboxylic acid, C2-C12 aliphatic dicarboxylic acid, such as succinic acid, adipic acid, azelaic acid, sebacic acid, and dodecanoic acid, C8-115, such as terephthalic acid, isophthalic acid, and phthalic acid Examples thereof include aromatic dicarboxylic acids, ester-forming derivatives of these dicarboxylic acids (such as acid anhydrides and lower alkyl esters having 1 to 4 carbon atoms), and mixtures of two or more thereof. Examples of the lactone include ε-caprolactone, γ-butyrolactone, γ-valerolactone, and a mixture of two or more thereof.
[0031]
Polyesterification is carried out by a conventional method such as dihydric alcohol and / or polyether diol having a molecular weight of 1,000 or less, dicarboxylic acid or an ester-forming derivative thereof, or an anhydride thereof and AO (for example, EO and / or PO). ) And a method of adding a lactone to an initiator (low molecular diol and / or polyether diol having a molecular weight of 1,000 or less).
[0032]
Specific examples of these polyester diols (b2) include polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyneopentyl adipate diol, polyethylene propylene adipate diol, polyethylene butylene adipate diol, polybutylene hexamethylene adipate diol , Polydiethylene adipate diol, poly (polytetramethylene ether) adipate diol, polyethylene azelate diol, polyethylene sebacate diol, polybutylene azelate diol, polybutylene sebacate diol, polycaprolactone diol, 3 methylpentanediol and 2 carbon atoms Polyester diol synthesized from ˜20 aliphatic dicarboxylic acids, Hexamethylene carbonate diol.
[0033]
The number average (calculated from OH number) molecular weight of the polyester diol (b2) is preferably 500 to 5,000, more preferably 700 to 4,500, and still more preferably 1,000 to 4,000. .
[0034]
Examples of the polybutadiene diol (b3) include those having a 1,2-vinyl structure, those having a 1,2-vinyl structure and a 1,4-trans structure, and those having a 1,4-trans structure. The ratio of the 1,2-vinyl structure and the 1,4-trans structure can be variously changed, and for example, the molar ratio is preferably 100: 0 to 0: 100. Polybutadiene glycol (b3) also includes homopolymers and copolymers (styrene-butadiene copolymers, acrylonitrile-butadiene copolymers, etc.), and hydrogenated products thereof, and the hydrogenation rate of such hydrogenated products is preferably 20 to 100%. It is.
[0035]
The number average (calculated from OH number) molecular weight of the polybutadiene diol (b3) is preferably 500 to 5,000, more preferably 700 to 4,500, and still more preferably 1,000 to 4,000. .
[0036]
Polyalkylene ether diol (b1) is preferred as the polymer diol (b), and PTMG, THF / EO copolymerized diol and THF / 3M-THF copolymerized diol are particularly preferred.
[0037]
Examples of the low molecular diol (c) used in the present invention include EG, propylene glycol, 1,3-propanediol (hereinafter abbreviated as 3G), 1,3-butylene glycol, 14BG, 1,6-hexane. Aliphatic glycols having 2 to 8 carbon atoms such as diol, DEG and neopentyl glycol, for example, alicyclic diols having 6 to 10 carbon atoms such as 1,4-cyclohexanediol and 1,4-bis (hydroxymethyl) cyclohexane Examples thereof include diols having 8 to 20 carbon atoms such as xylylene glycol, bis (hydroxyethyl) benzene, bis (hydroxyethoxy) benzene, ethylene oxide adduct of bisphenol A, and the like. From the viewpoint of obtaining a final product having high strength and excellent physical properties such as heat resistance and light resistance, among these, preferred are aliphatic glycols, more preferred are EG, DEG, 14BG, and 3G. Preferred are EG, 14BG and 3G.
[0038]
The molecular weight of the low molecular diol (c) is preferably 300 or less, more preferably 62 to 120.
[0039]
Examples of the monohydric alcohol (d1) having a molecular weight of 200 or less used in the present invention include alkanols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, octyl alcohol, etc. Cellosolves such as ethyl cellosolve and butyl cellosolve, for example, aliphatic monohydric alcohols having 1 to 10 carbon atoms such as carbitols such as ethyl carbitol and butyl carbitol, such as 6 to 10 carbon atoms such as cyclohexanol. Alicyclic monohydric alcohols, for example, monovalent alcohols containing tertiary amino groups such as N, N-dimethylaminoethanol, N-hydroxyethylmorpholine, monovalent alcohols having 7 to 15 carbon atoms such as benzyl alcohol, etc. Alcoa , For example, phenol, AO monovalent phenols such as cresol (e.g., EO and / or PO), and the like adducts. Of these, preferred are aliphatic monohydric alcohols, and particularly preferred are alkanols, particularly n-propyl alcohol, isopropyl alcohol, n-butyl alcohol and isobutyl alcohol.
[0040]
Examples of the organic solvent used in the present invention include amides such as N, N-dimethylformamide (hereinafter abbreviated as DMF), N, N-dimethylacetamide (hereinafter abbreviated as DMAC), and N-methylpyrrolidone. Solvents, sulfoxide solvents such as dimethyl sulfoxide, ketone solvents such as methyl ethyl ketone, ether solvents such as dioxane and THF, ester solvents such as methyl acetate, ethyl acetate and butyl acetate, aromatic solvents such as toluene and xylene, etc. And a mixture of two or more of these. Of these, amide solvents are preferable, and DMF and DMAC are particularly preferable.
[0041]
The monohydric alcohol (d2) as a reaction terminator used in the present invention is preferably the same as the monohydric alcohol (d1) described above.
[0042]
Examples of the monoamine (d3) as a reaction terminator used in the present invention include ethylamine, n-propylamine, isopropylamine, n-butylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine and the like. A mono- or dialkylamine having 1 to 8 carbon atoms of the alkyl group, for example, an alicyclic monoamine having 6 to 10 carbon atoms such as cyclohexylamine, for example, an aromatic monoamine having 6 to 10 carbon atoms such as aniline, for example, mono Examples thereof include mono- or dialkanol amines having 2 to 4 carbon atoms of alkanol groups such as ethanolamine, monoisopropanolamine, diethanolamine and disopropanolamine, heterocyclic monoamines such as morpholine, and mixtures of two or more thereof. . Of these, preferred are dialkylamines.
[0043]
In the production of the polyurethane resin solution of the present invention, an organic diisocyanate can be obtained from the viewpoint of easily obtaining a desired viscosity and molecular weight, excellent solution viscosity stability, and excellent resin strength. The equivalent ratio of (a) to the active hydrogen group-containing compound comprising the high molecular diol (b), the low molecular diol (c) and the monohydric alcohol (d1) is preferably 0.95: 1 to 1.1. Yes, more preferably from 0.97: 1 to 1.05: 1.
[0044]
The equivalent ratio of the high molecular diol (b) to the low molecular diol (c) is preferably 1: 0.5 to 1: 8, more preferably 1 from the viewpoint of excellent resin strength and elongation. : 0.8 to 1: 5.
[0045]
In the present invention, it is important that the equivalent ratio of the sum of the high molecular diol (b) and the low molecular diol (c) to the monohydric alcohol (d1) is 1: 0.001 to 1: 0.03.
[0046]
When the ratio of the monohydric alcohol (d1) is less than 0.001, there is a problem that the viscosity stability of the resin solution becomes poor.
[0047]
Moreover, when the ratio of monohydric alcohol (d1) exceeds 0.03, there is a problem that the desired viscosity and molecular weight cannot be obtained, resulting in poor resin strength.
[0048]
The equivalent ratio of the sum of the high molecular diol (b) and the low molecular diol (c) to the monohydric alcohol (d1) is preferably 1: 0.002 to 1: 0.02.
[0049]
The number average molecular weight (by GPC method) of the polyurethane resin is preferably 20,000 to 200,000, more preferably 40, from the viewpoint of excellent resin strength and favorable viscosity stability. 000 to 150,000.
[0050]
The amount of the monohydric alcohol (d2) used as the reaction terminator is 3 to 3 with respect to the remaining free NCO groups in the reaction system from the viewpoint of preventing the viscosity of the solution from increasing with time and obtaining good viscosity stability. It is preferably 50 times equivalent, and more preferably 5 to 30 times equivalent.
[0051]
The content of free NCO groups remaining in the reaction system subjected to the sealing reaction with the monohydric alcohol (d2) is preferably 0.01 to 0.1% by weight per resin solid content, and preferably 0.02 to 0.06% by weight. % Is more preferred.
[0052]
When the reaction terminator is monoamine (d3), the amount used is preferably 1 to 1.5 equivalents, more preferably 1 to 1.1 equivalents, relative to the remaining free NCO groups.
[0053]
A polyurethane resin solution is produced by reacting an organic diisocyanate (a), a high molecular diol (b), a low molecular diol (c), and a monohydric alcohol (d1) in the presence of an organic solvent by a one-shot method. The NCO group is subjected to a terminal termination reaction with a monohydric alcohol (d2) or a monoamine (d3) when the amount of NCO group to be obtained reaches a specific amount.
[0054]
The resin content concentration of the polyurethane resin solution is preferably set from the viewpoint of obtaining the desired solution viscosity and preventing the viscosity stability from becoming poor due to viscosity increase over time, and obtaining versatility of use, storage properties, and delivery properties. Is 30 to 50% by weight, more preferably 37 to 45% by weight.
[0055]
Reaction temperature may be the same as the temperature normally employ | adopted for a polyurethane-ized reaction, Preferably it is 20-100 degreeC, More preferably, it is 40-80 degreeC.
[0056]
The viscosity (20 ° C.) of the obtained polyurethane resin solution is preferably 500,000 to 1,500,000 mPa · s, more preferably from the viewpoints of versatility of use, storage properties, delivery properties, and viscosity stability. 600,000 to 1,300,000 mPa · s.
[0057]
In order to accelerate the reaction, it is also preferable to use a catalyst usually used for polyurethane reaction, if desired.
[0058]
As the catalyst, for example, amine catalysts such as triethylamine and triethylenediamine, and tin catalysts such as dibutyltin dilaurate and dioctyltin dilaurate are preferable.
[0059]
The amount of the catalyst used is preferably 1% by weight or less based on the polyurethane resin.
[0060]
In the polyurethane resin solution obtained by the production method of the present invention, a colorant such as titanium oxide, various stabilizers such as an ultraviolet absorber and an antioxidant, inorganic fillers, organic modifiers, other additives and the like are optionally added. It is preferable to contain.
[0061]
The polyurethane resin solution obtained by the production method of the present invention can be widely used for various applications.
Typical applications include artificial leather, synthetic leather, various coating materials, and elastic fibers.
[0062]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this. The part in an Example and a comparative example represents a weight part, and% represents weight%.
The evaluations of viscosity, solution viscosity stability, resin number average molecular weight, film production, strong elongation physical properties and elastic recovery in the examples were carried out according to the following methods.
[0063]
(1) Viscosity
The sample (polyurethane resin solution) was temperature-controlled in a constant temperature bath at 20 ° C. for 5 hours, and then measured with a B-type viscometer [BH viscometer manufactured by Toki Sangyo Co., Ltd.].
[0064]
(2) Solution viscosity stability
The sample (polyurethane resin solution) was stored in a constant temperature bath at 40 ° C. for 20 days, and after storage, the temperature was adjusted to 20 ° C. and the viscosity was measured.
[0065]
(3) Number average molecular weight
The molecular weight was measured using HLC-8020 (column: Tosoh GMH-XL) manufactured by Tosoh Corporation.
[0066]
(4) Production of film
The polyurethane resin solution was applied to a release-treated glass plate to a thickness of 0.7 mm, dried with a circulating dryer at 70 ° C. for 3 hours, and then peeled off from the glass plate to form a film having a thickness of about 0.2 mm. A film was formed.
[0067]
(5) High elongation properties
After leaving the film to be used for measurement at room temperature for 3 days, the strength and elongation properties were measured according to JISK-6301.
[0068]
(6) Elastic recovery rate
After leaving the film to be used for measurement at room temperature for 3 days, the film is cut into 1 cm × 9 cm, and marked lines are drawn at intervals of 5 cm in the length direction to obtain test samples.
Next, the sample was stretched 300% and held for 2 minutes at a pulling speed of 200 mm / min using an autograph AGS-500D manufactured by Shimadzu Corporation, and then the elastic recovery was measured by removing the tension.
[0069]
[Example 1]
In a four-necked flask equipped with a stirrer and a thermometer, 230 parts of PTMG having a number average (calculated from OH value) of 2,300, 21.1 parts of 14BG having a molecular weight of 90, 84.5 parts of MDI, 2.03 of n-propyl alcohol Parts and DMAC 503 parts, reacted at 70 ° C. for 5 hours under a dry nitrogen atmosphere, then added 3.4 parts of n-propyl alcohol [the free NCO content in the reaction system at this time (in terms of resin solid content) The reaction was terminated for 1 hour to obtain a polyurethane resin solution (A1) having a resin concentration of 40%, a viscosity of 700,000 mPa · s / 20 ° C., and a number average molecular weight of 65,000. The obtained polyurethane resin solution (A1) was stored at 40 ° C. for 20 days, but no particular change in viscosity or turbidity occurred. The polyurethane resin solution was coated on glass and dried at 70 ° C. for 3 hours to form a film. Table 1 shows the physical properties of the obtained film. The surface had good characteristics with no irregularities.
[0070]
[Example 2]
In the same reaction vessel as in Example 1, 310 parts of PTMG having a number average (calculated from OH number) molecular weight of 3,100, 16.3 parts of EG having a molecular weight of 62, 91.5 parts of MDI, 5.42 parts of n-butyl alcohol and 577 parts of DMF Was added, and then 7.0 parts of n-butyl alcohol was added [the free NCO content in the reaction system at this time (in terms of resin solid content) was 0. It was 048%] A terminal termination reaction was performed for 1 hour to obtain a polyurethane resin solution (A2) having a resin concentration of 42%, a viscosity of 1,000,000 mPa · s / 20 ° C., and a number average molecular weight of 58,000. The obtained polyurethane resin solution (A2) was stored at 40 ° C. for 20 days, but no particular change in viscosity or turbidity occurred. The polyurethane resin solution was coated on glass and dried at 70 ° C. for 3 hours to form a film. The physical properties of the obtained film are also shown in Table 1. The surface had good characteristics with no irregularities.
[0071]
[Example 3]
In the same reaction vessel as in Example 1, 350 parts of a copolymerized diol having a number average (calculated from OH number) molecular weight of 3,500 THF / 3M-THF (molar ratio: 85/15) and a molecular weight of 62 EG24.8. , 126 parts of MDI, 1.82 parts of n-propyl alcohol and 784 parts of DMAC and reacted at 70 ° C. for 8 hours under a dry nitrogen atmosphere, then 6.4 parts of n-propyl alcohol was added [reaction at this time The free NCO content in the system was 0.036% (in terms of resin solids)] The reaction was terminated for 1 hour, the resin concentration was 39%, the viscosity was 800,000 mPa · s / 20 ° C., the number average molecular weight was 63, 000 polyurethane resin solution (A3) was obtained. The obtained polyurethane resin solution (A3) was stored at 40 ° C. for 20 days, but no particular change in viscosity or turbidity occurred. The polyurethane resin solution was coated on glass and dried at 70 ° C. for 3 hours to form a film. The physical properties of the obtained film are also shown in Table 1. The surface had good characteristics with no irregularities.
[0072]
[Example 4]
In the same reaction vessel as in Example 1, 290 parts of a copolymerized diol having a number average (calculated from the OH number) molecular weight of 2,900, THF / EO (molar ratio: 90/10), EG having a molecular weight of 62, 17.7 parts, 97.5 parts of MDI, 1.73 parts of n-butyl alcohol and 583 parts of DMAC were charged and reacted at 70 ° C. for 9 hours under a dry nitrogen atmosphere. Next, 3.0 parts of n-butyl alcohol was added [reaction at this time. The free NCO content in the system was 0.041% (in terms of resin solid content)] The reaction was terminated for 1 hour, the resin concentration was 41%, the viscosity was 900,000 mPa · s / 20 ° C., the number average molecular weight was 56, 000 polyurethane resin solution (A4) was obtained. The obtained polyurethane resin solution (A4) was stored at 40 ° C. for 20 days, but no particular change in viscosity or turbidity occurred. The polyurethane resin solution was coated on glass and dried at 70 ° C. for 3 hours to form a film. The physical properties of the obtained film are also shown in Table 1. The surface had good characteristics with no irregularities.
[0073]
[Example 5]
In a reaction vessel similar to that of Example 1, 230 parts of PTMG having a number average (calculated from OH number) molecular weight of 2,300, 21.1 parts of 14BG having a molecular weight of 90, 84.5 parts of MDI, 0.20 part of n-propyl alcohol and 503 parts of DMAC And then reacted at 70 ° C. for 5 hours under a dry nitrogen atmosphere, and then 0.394 parts of di-n-butylamine was added [the free NCO content in the reaction system at this time (in terms of resin solid content) was 0. The end-stop reaction was performed for 1 hour to obtain a polyurethane resin solution (A5) having a resin concentration of 40%, a viscosity of 710,000 mPa · s / 20 ° C., and a number average molecular weight of 66,000. The obtained polyurethane resin solution (A5) was stored at 40 ° C. for 20 days, but no particular change in viscosity or turbidity occurred. The polyurethane resin solution was coated on glass and dried at 70 ° C. for 3 hours to form a film. The physical properties of the obtained film are also shown in Table 1. The surface had good characteristics with no irregularities.
[0074]
[Comparative Example 1]
In a reaction vessel similar to that of Example 1, 230 parts of PTMG having a number average molecular weight of 2,300, 21.1 parts of 14BG, 84.5 parts of MDI and 503 parts of DMAC were charged and reacted at 70 ° C. for 5 hours in a dry nitrogen atmosphere. 0.4 parts of n-propyl alcohol was added [the free NCO content in the reaction system at this time was 0.043% (in terms of resin solid content)], and the terminal termination reaction was performed for 1 hour, and the resin concentration was 40%. A polyurethane resin solution (H1) having a viscosity of 720,000 mPa · s / 20 ° C. and a number average molecular weight of 65,000 was obtained. Obtained polyurethane resin solution (H1) was obtained. After the obtained polyurethane resin solution (H1) was stored at 40 ° C. for 20 days, an attempt was made to form a film in the same manner as in Example 1. However, since no monohydric alcohol was initially charged, the viscosity increased and the solution viscosity increased. Because the stability was inferior, fine irregularities were formed on the surface, and a good film could not be obtained.
[0075]
[Comparative Example 2]
A reaction vessel similar to Example 1 was charged with 310 parts of PTMG having a number average (calculated from OH number) molecular weight of 3,100, 16.3 parts of EG having a molecular weight of 62, 91.5 parts of MDI and 577 parts of DMF, and 70 under a dry nitrogen atmosphere. The mixture was reacted at 5 ° C. for 5 hours, and then 13.1 parts of n-butyl alcohol was added [the free NCO content in the reaction system at this time was 0.036% (in terms of resin solid content)] A termination reaction was carried out to obtain a polyurethane resin solution (H2) having a resin concentration of 42%, a viscosity of 610,000 mPa · s / 20 ° C., and a number average molecular weight of 48,000. The obtained polyurethane resin solution (H2) was stored at 40 ° C. for 20 days, and then used as a film. Since no monohydric alcohol was initially charged, the solution viscosity stability was inferior, and the resulting film had low strength, low elongation, and low recoverability.
[0076]
[Table 1]

[0077]
As is clear from Table 1, the polyurethane resin solutions of Examples 1 to 5 of the present invention have remarkably good solution viscosity stability as compared with Comparative Examples 1 and 2, and the obtained films have high strength properties. It is in. On the other hand, the polyurethane resin solutions of Comparative Examples 1 and 2 have poor solution viscosity stability and cannot be put to practical use.
[0078]
【The invention's effect】
The polyurethane resin solution obtained by the method of the present invention is excellent in solution viscosity stability, and retains almost the same solution properties as immediately after production even after long-term storage.
[0079]
Because of the above effects, the polyurethane resin solution obtained by the method of the present invention is particularly useful as a raw material for various uses, for example, artificial leather, synthetic leather, various coating materials, elastic fibers and the like.

Claims (8)

An organic diisocyanate (a), a high molecular diol (b) having a number average molecular weight of 500 to 5,000, a low molecular diol (c) having a molecular weight of 300 or less, and a monohydric alcohol (d1) having a molecular weight of 200 or less in an organic solvent. In the reaction, the monohydric alcohol (d1) is 0.001 to 0.03 equivalent to the total of the high molecular diol (b) and the low molecular diol (c). A method for producing a polyurethane resin solution, comprising adding monohydric alcohol (d2) at a stage when the content of free isocyanate groups per unit becomes 0.01 to 0.1% by weight. The method for producing a polyurethane resin solution according to claim 1, wherein the monohydric alcohol (d2) is at least 3 times equivalent to the isocyanate group. An organic diisocyanate (a), a high molecular diol (b) having a number average molecular weight of 500 to 5,000, a low molecular diol (c) having a molecular weight of 300 or less, and a monohydric alcohol (d1) having a molecular weight of 200 or less in an organic solvent. In the reaction, the monohydric alcohol (d1) is 0.001 to 0.03 equivalent to the total of the high molecular diol (b) and the low molecular diol (c). A process for producing a polyurethane resin solution, comprising adding monoamine (d3) at a stage where the content of free isocyanate groups per unit becomes 0.01 to 0.1% by weight. The method for producing a polyurethane resin solution according to claim 3, wherein the monoamine (d3) is 1 to 1.5 equivalents relative to the isocyanate group. The method for producing a polyurethane resin solution according to any one of claims 1 to 4, wherein the number average molecular weight of the polyurethane resin is 20,000 to 200,000. 6. The method for producing a polyurethane resin solution according to claim 1, wherein the resin content concentration of the solution is 30 to 50% by weight. The method for producing a polyurethane resin solution according to any one of claims 1 to 6, wherein the viscosity of the solution is 500,000 to 1,500,000 mPa · s / 20 ° C. The organic diisocyanate (a) is diphenylmethane diisocyanate, and the polymer diol (b) is polytetramethylene ether glycol, tetrahydrofuran / ethylene oxide copolymer diol, and tetrahydrofuran / 3-methyltetrahydrofuran copolymer. The organic solvent is at least one selected from the group consisting of polymerized diols, and the organic solvent is N, N-dimethylformamide and / or N, N-dimethylacetamide. 2. A method for producing a polyurethane resin solution according to item 1.