JP3201532B2 - Polyurethane emulsion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane emulsion which is excellent in hydrolysis resistance, durability and flexibility, in particular, low temperature feeling.

[0002]

2. Description of the Related Art Polyurethane emulsions are widely used in paints, adhesives and coatings because they provide a coating film having abrasion resistance, adhesion, non-tackiness and rubber elasticity. However, compared with the properties obtained from the solvent-based polyurethane resin, the physical properties of the coating film obtained from the emulsion were considerably inferior in water resistance among the film strengths. In particular, in the case of a polyurethane emulsion using a polyester diol, not only the hydrolysis resistance of the film formed is poor, but also a problem that the molecular weight is reduced during storage of the emulsion actually occurs. In addition, when polyether diol is used, there is a problem that heat resistance is insufficient and satisfactory physical properties cannot be obtained, or when applied to artificial leather, abrasion resistance cannot be sufficiently obtained. Has long been desired. Recently, polycarbonate diols have appeared, and the conventional problems such as hydrolysis resistance, heat resistance, and abrasion resistance have been solved, and physical properties have been improved.

[0003]

However, conventional polycarbonate diols are crystalline, and films obtained from polyurethane emulsions using the same are inferior in soft feel, especially at low temperatures, and therefore, improvements are desired. Was rare.

[0004]

Means for Solving the Problems The present inventors have overcome the above-mentioned problems of the prior art and have a good film-forming property when practically used, and have hydrolysis resistance, durability, heat resistance, With the aim of providing a polyurethane emulsion useful as a coating agent, adhesive, and coating composition having excellent abrasion resistance and good texture, especially flexibility at low temperatures, as a result of intensive studies, amorphous polycarbonate was obtained. It has been found that a polyurethane emulsion using a diol is good, and the present invention has been completed.

That is, the present invention comprises (1) an organic diisocyanate, (2) an amorphous polycarbonate diol, and (3) a compound having one hydrophilic center and at least two isocyanate-reactive groups. A polyurethane emulsion comprising a reaction product of a urethane prepolymer and a chain extender. Hereinafter, the present invention will be described.

Examples of the amorphous polycarbonate diol used in the present invention include those which are viscous liquids at room temperature. Among them, aliphatic polycarbonate diols are more preferable, and the repeating unit is preferably (A)
(B) Consisting of the formula (C), the ratio of A and B is 9: 1 to 1:
9, the total amount of one or more of C is 0 to 10% based on the total amount of A, B, and C (however, the% and the ratio indicate the number of repeating units). Diols are preferred.

[0007]

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The organic diisocyanate used in the present invention includes, for example, 2,4-tolylene diisocyanate,
2,6-tolylene diisocyanate and its mixture (TDI), diphenylmethane-4,4'-diisocyanate (MDI), naphthalene-1,5-diisocyanate (NDI), 3,3'-dimethyl-4,4'-biphenylene Diisocyanate (TODI), crude TDI,
Polymethylene polyphenyl diisocyanate, crude MD
I, and other aromatic diisocyanates, xylylene diisocyanate (XDI), phenylene diisocyanate, and other aromatic alicyclic diisocyanates; and 4,4'-methylenebiscyclohexyl diisocyanate (hydrogenated MD
Aliphatic diisocyanates such as I), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and cyclohexane diisocyanate (hydrogenated XDI).

The compound having one hydrophilic center and at least two isocyanate-reactive groups is represented by the following formula:

[0010]

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Examples of the diols include 2,2-dimethylrolpropionic acid, 2,2-dimethyllolbutyric acid, and 2,2-dimethylolvaleric acid.
Further, diaminocarboxylic acids such as lysine, cystine and 3,5-aminocarboxylic acid are exemplified. When these are actually used, they are neutralized with amine acids such as trimethylamine, triethylamine, tri-n-propylamine, tributylamine and triethanolamine, sodium hydroxide, potassium hydroxide, ammonia and the like. Naturally, suitable surfactants, for example, anions represented by higher fatty acids, resin acids, acidic fatty alcohols, sulfates, higher alkyl sulfonates, alkylaryl sulfonates, sulfonated castor oil, sulfosuccinate esters, etc. Surfactant or
Emulsion stability may be maintained by using a nonionic surfactant typified by a known reaction product of ethylene oxide with a long-chain fatty alcohol or phenol.

The chain extenders used in the present invention include short-chain diols such as ethylene glycol and 1,4-butanediol, ethylenediamine, propylenediamine, hexamethylenediamine, tolylenediamine, xylylenediamine, diphenyldiamine, diaminodiamine. Diphenylmethane, diaminocyclohexylmethane, piperazine, 2-
Examples include various diamines such as methylpiperazine and isophoronediamine, and water.

The polyurethane emulsion of the present invention is prepared by, for example, reacting an organic diisocyanate, an amorphous polycarbonate diol, and a compound having one hydrophilic center with at least two isocyanate-reactive groups to form an NCO-terminal compound. Obtain a urethane prepolymer. For the reaction, an organic solvent inert to isocyanate such as acetone, methyl ethyl ketone, toluene, dioxane dimethylformamide, N-methylpyrrolidone, and tetrahydrofuran can be used. Next, if necessary, the obtained prepolymer is neutralized, then emulsified and dispersed in water, and made high molecular weight with a chain extender. When the prepolymer reaction is performed using a solvent, for example, it is necessary to remove by a method such as distillation under reduced pressure after completion of the chain extension reaction.

[0014]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. Parts in the examples mean parts by weight. Synthesis Example of Amorphous Polycarbonate Diol (1 ) 416 parts (4.0 mol) of 1,5-pentanediol and 1,6-hexanediol were placed in a reactor equipped with a stirrer, a thermometer, a fractionating tower, and a vacuum pump. 472 parts (4.
0 mol) and metallic sodium at 70-80 ° C.
84 parts (0.08 mol) were added with stirring. After the sodium had completely reacted, 472 parts (8.0 mol) of diethyl carbonate were introduced. Reaction temperature is 59-10
When the temperature was raised to 0 ° C, ethanol began to be distilled. The temperature was gradually raised to 160 ° C. in about 6 hours. During this time, ethanol containing about 10% diethyl carbonate was distilled off. Thereafter, the pressure in the reactor was further reduced to 10 mmHg or less, and the reaction was carried out at 200 ° C. for 4 hours under strong stirring. The resulting polymer was cooled, dissolved in dichloromethane, neutralized with dilute acid, washed several times with water, dehydrated with anhydrous sodium sulfate, and then distilled off the solvent.
Dry at 140 ° C. for several hours at mHg. The number average molecular weight of the obtained amorphous polycarbonate diol (hereinafter abbreviated as C5,6-PCDL) was 2,000. Synthesis Example of Amorphous Polycarbonate Diol (2 ) In the same manner as in Synthesis Example (1), 360 parts (4.0 mol) of 1,4-butanediol were used instead of 1,5-pentanediol. Polycarbonate diol (hereinafter abbreviated as C4,6-CDL) was obtained. The C4,6-
The number average molecular weight of PCDL was 2000. Synthesis Example of Amorphous Polycarbonate Diol (3 ) In the same manner as in Synthesis Example (1), 360 parts (4.0 mol) of 1,4-butanediol was used instead of 1,6-hexanediol. A crystalline polycarbonate diol (hereinafter abbreviated as C4,5-PCDL) was obtained. The C4,5
-The number average molecular weight of PCDL was 2000.

[0015]

Example 1 The above C5,6-PCDL (molecular weight: 200
0) 500 parts, hexamethylene diisocyanate (HD
I) 126 parts, 58.5 parts of dimethylolpropionic acid whose carboxyl group was neutralized with triethylamine, and 1027 parts of methyl ethyl ketone (MEK) were placed in a reactor having a reflux condenser, a thermometer, and a stirrer. The urethanization reaction was performed for an hour to obtain an NCO-terminated prepolymer solution. The prepolymer solution was dissolved in 7 parts of sodium dodecylbenzenesulfonate (Na-DBS),
It was gradually added to 1578 parts of distilled water set to a temperature of 0 ° C. while stirring to prepare an emulsion of a prepolymer solution. Thereafter, isophoronediamine (I
After adding 106.5 parts of a 20% aqueous solution of PDA) over 30 minutes, the temperature was raised to 40 ° C., and the mixture was reacted for 1 hour to increase the molecular weight. The MEK was removed under reduced pressure to obtain a solid content of 3.
A 0% polyurethane emulsion (1) was obtained. The emulsion was allowed to stand for 3 days, then formed into a film, and subjected to a heat treatment at 120 ° C. for 20 minutes.
It measured under the measurement atmosphere of ° C. Table 1 shows the obtained results.

[0016]

Examples 2-3 The amorphous polycarbonate diols having the compositions shown in Table 1 were converted to C4,5-PCDL or C4,
Except having changed to 6-PCDL, polyurethane emulsions (2) and (3) were obtained in the same manner as in Example 1, and the strong elongation of a film obtained by forming these emulsions in the same manner as in Example 1 was determined. The measurement was performed in the same manner as in Example 1. Table 1 shows the obtained results.

[0017]

Comparative Example 1 A polyurethane emulsion was obtained in the same manner as in Example 1 except that the polycarbonate diol was changed to C6-PCDL (Carbodiol D-2000 manufactured by Toagosei Co., Ltd.) in the composition shown in Table 1. . The strong elongation of a film obtained by forming a film of the emulsion in the same manner as in Example 1 was measured in the same manner as in Example 1. Table 1 shows the obtained results.

[0018]

Example 4 0.1 denier (2
A 50 d / 2500 f) PET ultrafine fiber was manufactured and cut into a length of 5 mm. It was dispersed in water to obtain a slurry for papermaking. The slurry was made into a non-woven web having a basis weight of 80 g / m ² , and a 75-denier / 36-filament P
The nonwoven web was laminated on both sides of a plain woven fabric made of ET fiber with a basis weight of 50 g / m ² , and three-dimensionally entangled and integrated by high-speed water jet. The high-speed water flow was injected at a pressure of 30 kg / cm ² from a straight flow injection nozzle having a hole diameter of 0.1 mm. This operation was performed from both the front and back surfaces of the laminated sheet, and the basis weight was 210 g / m ² , the thickness was 0.95 mm, and the apparent density was 0.
A 22 g / m ² sheet was produced. This sheet was formed using emery paper No. 240 at a paper speed of 7
The surface was puffed at 00 m / min to a thickness of 0.9 mm. It has a viscosity of 6.0 centipoise and a saponification degree of 86-8.
A mixture of a 6% PVA concentration and a 7% polyurethane emulsion solids concentration obtained by mixing an 18% aqueous solution of 9 mol% polyvinyl alcohol (PVA) with the polyurethane emulsion obtained in Example 1 was prepared by raising the hair in the above step. After immersing the woven sheet material and squeezing with a mangle to adjust the impregnation amount of the mixture to 2.5 times that of the sheet material,
And heated and dried for 4 minutes with a hot air dryer of a pinch tenter type.
When the sheet-like composite is observed with a microscope, the surface of the nap is P
VA adhered and no piloerection was observed. Next, the sheet composite was put into hot water to extract PVA, washed well with water, and dried to obtain a suede-like artificial leather. The hydrolysis resistance and abrasion resistance of this suede-like artificial leather were measured and evaluated by the following methods. Table 2 shows the results.

Abrasion resistance: A test was conducted with a load of 2.5 kg using a plane abrasion tester, and the number of wears until the surface layer was worn and the intermediate layer appeared was measured. Hydrolysis resistance: 2 days at 120 ° C after film formation at room temperature for 3 days
The film that had been heat-treated for 0 minutes was immersed in hot water at 100 ° C. for 30 minutes, and then the breaking strength was measured.

Retention rate exceeds 85% ○ ○ 50-85 △ 未 満 Less than 50% ×

[0021]

Comparative Examples 2-3 The polyether polyol having a composition shown in Table 3 and a molecular weight of 2,000 [PTM manufactured by Asahi Kasei Kogyo Co., Ltd.]
G], and a polyurethane emulsion was obtained in the same manner as in Example 1 except that a polyester polyol having a molecular weight of 2,000 [Polylite ODX-668 manufactured by Dainippon Ink and Chemicals, Inc.] was used. Using these emulsions, a suede-like artificial leather was produced in the same manner as in Example 4, and the hydrolysis resistance and abrasion resistance were measured. Table 2 shows the results.

[0022]

Example 5 A polyurethane emulsion was obtained in the same manner as in Example 1 except that the diisocyanate was changed to isophorone diisocyanate (IPDI) in the composition shown in Table 3. In the same manner as in Example 4 using the emulsion,
Suede-like artificial leather was prepared, and hydrolysis resistance and abrasion resistance were measured. Table 3 shows the results.

[0023]

Comparative Examples 4 to 6 Polyurethane emulsions were obtained in the same manner as in Example 1 except that the polyols were changed to polyether polyols and polyester polyols in the compositions shown in Table 3. Using this emulsion, a suede-like artificial leather was produced in the same manner as in Example 4, and the hydrolysis resistance and the abrasion resistance were measured. Table 3 shows the results.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

Industrial Applicability The polyurethane emulsion of the present invention provides leather excellent in hydrolysis resistance, durability, and flexibility, particularly, low-temperature feel. Further, the polyurethane emulsion of the present invention is useful for a coating agent, an adhesive, a coating material, and the like.

Claims (1)

(57) [Claims] 1. A urethane prepolymer and chain comprising (1) an organic diisocyanate, (2) an amorphous polycarbonate diol, and (3) a compound having one hydrophilic center and at least two isocyanate-reactive groups. A polyurethane emulsion comprising a reaction product with an extender.